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7 May 2026

Reproducible Builds: Reproducible Builds in April 2026

Welcome to our April 2026 report from the Reproducible Builds project! Our reports outline what we ve been up to over the past month, highlighting items of news from elsewhere in the increasingly-important area of software supply-chain security. As ever, if you are interested in contributing to the Reproducible Builds project, please see the Contribute page on our website. In this month s report, we cover:

  1. Tor stateless relays and Reproducible Builds
  2. Civil Infrastructure Platform celebrates 10 years of supporting industrial grade Linux
  3. Reproducible Builds at LinuxFest NorthWest
  4. Reproducibility issues in Rust binaries that embed random bytes
  5. Distribution work
  6. Patches
  7. diffoscope development
  8. Documentation updates
  9. Misc news


Tor stateless relays and Reproducible Builds An interesting post was published on Tor Project blog by Osservatorio Nessuno OdV this month on stateless relays . These are stateless, diskless operating systems that are designed to be used as Tor exit relays. According to the post, which is titled A Server That Forgets: Exploring Stateless Relays:
For relay operators, this approach raises the security bar by enforcing better behaviors by design: [ ]
  1. Reproducibility. A system that doesn t change between reboots is easier to verify and, eventually, to reproduce and audit.
Furthermore, using a Trusted Platform Module (TPM), could allow for greater integrity in the future:
Transparency logs. Once you have a measured boot chain, you can publish it. A relay operator provides a recipe for a reproducible build; anyone can recompute the expected hash and verify it matches what the TPM reports. An append-only transparency log can make these attestations publicly auditable. The Tor community could run an independent monitor to track this across the relay fleet.

Civil Infrastructure Platform celebrates 10 years of supporting industrial grade Linux Congratulations to the Civil Infrastructure Platform (CIP) for reaching their 10-year anniversary last month. CIP has been a supporter of Reproducible Builds for many years, and we have collaborated on a number of technical issues that overlap. As Chris Lamb mentions in CIP s press release:
The collaboration between the Reproducible Builds project and CIP highlights a critical shift in how we approach industrial software. Through verifiability, CIP ensures that the open source foundation of our critical infrastructure is not only sustainable but also demonstrably secure. This commitment to transparency is vital for the trust and resilience required by critical systems over decades of operation.

Reproducible Builds at LinuxFest NorthWest Vagrant Cascadian and Chris Lamb hosted a table in the exposition hall at LinuxFest NorthWest 2026 this month in Bellingham, WA, USA, introducing many people to Reproducible Builds and answering questions both days of the conference. In addition, Vagrant presented Beyond Trusting Open Source Software on Sunday afternoon, exploring the intersection of Free/Open Source Software, Reproducible Builds and Bootstrappable builds, and how they all reinforce each other. Vagrant s slides are available online, including source code to build them reproducibly.

Reproducibility issues in Rust binaries that embed random bytes Reproducible Builds developer kpcyrd opened a ticket on the Rustsec issue tracker regarding binaries that deliberately inject random bytes into their binaries as a secret seed for a Hash Collision DoS mitigation. As kpcyrd notes in his message, this causes issues for reproducibility, and because the relevant end-user binaries are mostly distributed pre-compiled through package managers, those binaries (and by extension the secret seed) are public knowledge . kpcyrd goes on to note:
This is somewhat unique to Rust because Python/JavaScript doesn t compile binaries, and Go (to my knowledge) is too restrictive during build for any library to pull something like this.

Distribution work In Arch Linux this month, Robin Candau and Mark Hegreberg worked at adding a new repro tag/version to the Arch Linux Docker images providing a bit-for-bit reproducible image. Robin also shared a related announcement and implementation details on our mailing list. Arch Linux developer Robin Candau posted a blog post announcing that Arch Linux Now Has a Bit-for-Bit Reproducible Docker Image . Robin mentions one interesting caveat:
to ensure reproducibility, the pacman [package manager] keys have to be stripped from the image, meaning that pacman is not usable out of the box in this image. While waiting to find a suitable solution to this technical constraint, we are therefore providing this reproducible image under a dedicated tag as a first milestone. [ ]
The blog post was also discussed on Hacker News.
In Debian this month, 24 reviews of Debian packages were added, 7 were updated and 16 were removed this month adding to our knowledge about identified issues. Vagrant Cascadian performed Non-Maintainer Uploads (NMUs) in Debian for several packages with outstanding patches over a year old jakarta-jmeter, wxmplot, critcl, vcsh and magic-wormhole-transit-relay. In addition, Reproducible Builds developer Jochen Sprickerhof filed a bug against the APT package manager to request that APT should ignore [a] 0 epoch when downloading or installing with a version specifier . This is related to the special-case handling of the optional epoch prefix in Debian package version numbers.
In NixOS, Julien Malka presented Lila: Decentralized Build Reproducibility Monitoring for the Functional Package Management Model, a paper written together with Arnout Engelen at the Mining Software Repositories (MSR) ACM conference, where it was awarded the MSR 2026 FOSS Impact Award. Congratulations!
Lastly, in openSUSE, Michael Schroeder added reproducibility verification support in the Open Build Service [ ] and Bernhard M. Wiedemann posted another openSUSE monthly update for their reproducibility work there.

Patches The Reproducible Builds project detects, dissects and attempts to fix as many currently-unreproducible packages as possible. We endeavour to send all of our patches upstream where applicable or possible. This month, we wrote a large number of such patches, including:

diffoscope development diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb made a number of changes, including preparing and uploading versions, 316, 317 and 318 to Debian.
  • Chris Lamb:
    • Bump Standards-Version to 4.7.4. [ ]
    • Correct ordering of python3-guestfs architecture restrictions. [ ]
    • Limit python3-guestfs Build-Dependency to architectures that are not i386. [ ]
    • Try to fix PYPI_ID_TOKEN debugging. [ ]
  • Holger Levsen:
    • Add ppc64el to the list of python3-guestfs architecture whitelist. (Closes: #1132974). [ ]
In addition, Vagrant Cascadian updated diffoscope in GNU Guix to version 317.

Documentation updates Yet again, there were a number of improvements made to our website this month including:
  • Manuel Jacob:
    • Fix some minor wording issues on the Stable inputs page, and update information about the sorting behavior of GNU Make [ ].
    • On the Archives page, remove information about deterministic archives in historical Fedora versions [ ], add a note about .tar file portability [ ] and correct a section about .tar PAX headers [ ].
  • Mattia Rizzolo:
  • kpcyrd:
  • ktecho:

Misc news On our mailing list this month:
  • Timo Pohl posted our list inviting people to online group discussions with 4-6 participants each to talk about your perception of terms and requirements for reproducibility. As Timo notes:
    During our research of the existing literature, as well as my experience at the Reproducible Builds Summit 2025 in Vienna, we noticed that some of the terminology in the field is not used consistently across different groups of people, and that the precise meaning of some core terms like reproducibility of an artifact in itself is not uniform.
    As Timo mentions, the sessions will last roughly 90 minutes and will be rewarded with 50 per participant.
  • kpcyrd posted to the list asking for assistance with fixing an issue after updating the flake.lock file for their repro-env project.
  • Aman Sharma of the KTH Royal Institute of Technology, Sweden, posted to our list in order to share that Eric Cornelissen, a PhD student in KTH s CHAINS group, is maintaining an open-source project to monitor the reproducibility of GitHub Actions:
    The goal of the project is to assess whether GitHub Actions can be reproduced. Currently, it focuses on two types of Actions: JavaScript-based actions and Docker-based actions (composite actions are not considered). For JavaScript actions, the project rebuilds the distributed files and compares them bit-by-bit with the repository contents. For Docker actions, it rebuilds images from the Dockerfile and checks for semantic equivalence, using diffoci, across builds.


Finally, if you are interested in contributing to the Reproducible Builds project, please visit our Contribute page on our website. However, you can get in touch with us via:

3 May 2026

Jelmer Vernoo : Inquest, a test result repository in Rust

testrepository For a long time I ve used Robert Collins testrepository (testr) to run tests in many of the projects I work on. It s a small, focused tool built around a simple idea: decouple the running of tests from the recording and querying of their results. The way it works is straightforward. A test runner emits a subunit stream a compact binary protocol for test results and testrepository stores those streams in a per-project .testrepository/ directory. Once results are in the repository, you can ask questions like which tests failed in the last run? , re-run only the failures , what are the slowest tests? , or what changed between this run and the previous one? . The killer feature, for me, has always been the failing-test loop. When a big test suite breaks, you don t want to re-run the whole thing after every fix you want to iterate on just the failures, and only re-run the full suite once they re all green. testrepository made that workflow ergonomic long before most language-specific test runners had anything comparable, and many of them still don t have a good answer for it. testrepository has served me well for over a decade, but it has been largely unmaintained for a while, and I had some ideas of improvements that I wanted to try out. So I wrote a Rust port, which has since grown a number of features of its own.
Inquest Inquest is a Rust port of testrepository that has since grown a number of features of its own. The binary is called inq.
Goals The goals are deliberately modest:
  • a single static binary, no Python runtime required
  • no need to write a dedicated config file for most projects
  • compatible enough with testrepository s workflow that I can switch projects over without retraining my fingers
  • a richer on-disk format that captures more about each run (git commit, command line, duration, exit code, concurrency)
  • good support for the languages I actually use day-to-day: Rust, Python, Go, and Node.js
  • mostly Do What I Mean (DWIM), e.g. getting me to know as quickly as possible what tests are failing and why, and being clever about doing this
Inquest reads and writes subunit v2 streams, so anything that can produce subunit (directly or via one of the many converters) can feed into it.
Quick start Inquest can usually figure out how to run your tests on its own. In a Rust, Python, Go or Node.js project:
 $ cd my-project
 $ inq
Or if the auto-detection doesn t work, you can ask it to generate a config file and then run the tests:
 $ inq auto
 $ inq run
inq auto writes an inquest.toml describing how to invoke the test runner; inq run runs the tests, captures the subunit stream, and stores the results in a .inquest/ directory. For a Rust project the generated config looks like:
 test_command = "cargo subunit $IDOPTION"
 test_id_option = "--test $IDFILE"
 test_list_option = "--list"
After the first run, the usual queries work:
 $ inq stats             # repository-wide statistics
 $ inq last              # results of the most recent run
 $ inq failing           # only the failing tests
 $ inq slowest           # the slowest tests in the last run
 $ inq run --failing     # re-run only what failed last time
The last one is the workflow I use most often: run the full suite once, fix the obvious failures, then iterate on inq run --failing until the list is empty.
A few things that aren t in testrepository Some of the features that have grown in inquest beyond the original testrepository functionality:
  • Timeouts. --test-timeout, --max-duration, and --no-output-timeout will kill a test process that is hanging or has stopped producing output. --test-timeout auto derives a per-test timeout from the historical duration of that test, which is handy for catching tests that hang. Once the test runner is killed, the test is marked as failed and the next test is started, so a broken test doesn t hold up the whole suite.

  • Ordering --order can be used to run tests in a specific order, e.g. to run the slowest tests first, to run the tests that failed most recently first, or to run the widest variety of tests first to maximize the chance of finding a failure early on.

  • Live progress. inq running tails the in-progress subunit stream on disk and reports observed/expected test counts, percent complete, elapsed wall-clock time, and an ETA derived from each test s historical duration. Useful when a CI run is taking longer than you d like.

  • Flakiness ranking. inq flaky ranks tests by pass fail transitions in consecutive runs in which the test was recorded, so chronically broken tests rank low and genuinely flapping tests rank high.

  • Comparing runs. inq diff <A> <B> shows what changed between two test runs newly failing, newly passing, and tests that flipped state which makes it easy to see whether your last change actually fixed (or broke) anything.

  • Bisecting git history. inq bisect <TEST> drives git bisect to find the commit that broke a given test. It defaults the known-good and known-bad commits from the recorded run history (the most recent run where the test passed, and the most recent where it failed), so in the common case there is no need to remember either just point it at the test name and let it work.

  • Richer run metadata. inq info shows the git commit, command line, duration, exit code, and concurrency for a run, with a flag for whether the working tree was dirty when the run started. Combined with inq diff this makes it much easier to triangulate when a regression was introduced.

  • Rerun a previous run verbatim. inq rerun <ID> re-runs exactly the tests of a previous run, in the same order, forwarding the same -- arguments that the original run used. inq rerun -1 repeats the latest.

  • Web based view. inq web serves a web-based view of the repository, with a dashboard of recent runs and detailed views of individual runs and tests.

Web UI Most of the time I drive inquest from the command line, but for browsing historical results of a large suite spotting flapping tests, drilling into a single test s run history, or just getting a visual sense of which parts of the suite are hurting a web view is more pleasant. inq web starts a local server with exactly that:
 $ inq web
The repository overview shows totals and a per-test history grid where each cell is one run, coloured by outcome. Bands of red make it easy to pick out tests that have been broken for a long time, and isolated red cells in an otherwise green column point at flaky tests. Inquest web UI repository overview, with a grid of per-run results Drilling into an individual test gives you its full run history, a duration sparkline, and per-run pass/fail status: Inquest web UI per-test view with run history and duration sparkline
Migrating from testrepository If you already have a .testrepository/ directory full of historical runs, inq upgrade will migrate it into the new .inquest/ format, with a progress bar for the impatient. The legacy .testr.conf (INI) format is still understood, so existing projects don t have to be converted to inquest.toml immediately though the TOML format is preferred for new projects.
Trying it The source is on GitHub at jelmer/inquest. To install from source:
 $ cargo install inquest
In a project with a Rust, Python, Go or Node.js test suite:
 $ inq
Bug reports and patches are welcome.

9 March 2026

Colin Watson: Free software activity in February 2026

My Debian contributions this month were all sponsored by Freexian. You can also support my work directly via Liberapay or GitHub Sponsors. OpenSSH I released bookworm and trixie fixes for CVE-2025-61984 and CVE-2025-61985, both allowing code execution via ProxyCommand in some cases. The trixie update also included a fix for openssh-server: refuses further connections after having handled PerSourceMaxStartups connections. bugs.debian.org administration Gioele Barabucci reported that some messages to the bug tracking system generated by the bts command were being discarded. While the regression here was on the client side, I found and fixed a typo in our SpamAssassin configuration that was failing to apply a bonus specifically to forwarded commands, mitigating the problem. Python packaging New upstream versions: Porting away from the deprecated (and now removed from upstream setuptools) pkg_resources: Other build/test failures: Other bugs: I added a manual page symlink to make the documentation for Testsuite: autopkgtest-pkg-pybuild easier to find. I backported python-pytest-unmagic, a more recent version of pytest-django, and a more recent version of django-cte to trixie for use in Debusine. Rust packaging I also packaged rust-garde and rust-garde-derive, which are part of the pile of work needed to get the ruff packaging back in shape (which is a project I haven t decided if I m going to take on for real, but I thought I d at least chip away at a bit of it). Other bits and pieces Code reviews

22 February 2026

Otto Kek l inen: Do AI models still keep getting better, or have they plateaued?

Featured image of post Do AI models still keep getting better, or have they plateaued?The AI hype is based on the assumption that the frontier AI labs are producing better and better foundational models at an accelerating pace. Is that really true, or are people just in sort of a mass psychosis because AI models have become so good at mimicking human behavior that we unconsciously attribute increasing intelligence to them? I decided to conduct a mini-benchmark of my own to find out if the latest and greatest AI models are actually really good or not.

The problem with benchmarks Every time any team releases a new LLM, they boast how well it performs on various industry benchmarks such as Humanity s Last Exam, SWE-Bench and Ai2 ARC or ARC-AGI. An overall leaderboard can be viewed at LLM-stats. This incentivizes teams to optimize for specific benchmarks, which might make them excel on specific tasks while general abilities degrade. Also, the older a benchmark dataset is, the more online material there is discussing the questions and best answers, which in turn increases the chances of newer models trained on more recent web content scoring better. Thus I prefer looking at real-time leaderboards such as the LM Arena leaderboard (or OpenCompass for Chinese models that might be missing from LM Arena). However, even though the LM Arena Elo score is rated by humans in real-time, the benchmark can still be played. For example, Meta reportedly used a special chat-optimized model instead of the actual Llama 4 model when getting scored on the LM Arena. Therefore I trust my own first-hand experience more than the benchmarks for gaining intuition. Intuition however is not a compelling argument in discussions on whether or not new flagship AI models have plateaued. Thus, I decided to devise my own mini-benchmark so that no model could have possibly seen it in its training data or be specifically optimized for it in any way.

My mini-benchmark I crafted 6 questions based on my own experience using various LLMs for several years and having developed some intuition about what kinds of questions LLMs typically struggle with. I conducted the benchmark using the OpenRouter.ai chat playroom with the following state-of-the-art models: OpenRouter.ai is great as it very easy to get responses from multiple models in parallel to a single question. Also it allows to turn off web search to force the models to answer purely based on their embedded knowledge. OpenRouter.ai Chat playroom Common for all the test questions is that they are fairly straightforward and have a clear answer, yet the answer isn t common knowledge or statistically the most obvious one, and instead requires a bit of reasoning to get correct. Some of these questions are also based on myself witnessing a flagship model failing miserably to answer it.

1. Which cities have hosted the Olympics more than just once? This question requires accounting for both summer and winter Olympics, and for Olympics hosted across multiple cities. The variance in responses comes from if the model understands that Beijing should be counted as it has hosted both summer and winter Olympics. Interestingly GPT was the only model to not mention Beijing at all. Some variance also comes from how models account for co-hosted Olympics. For example Cortina should be counted as having hosted the Olympics twice, in 1956 and 2026, but only Claude, Gemini and Kimi pointed this out. Stockholm s 1956 hosting of the equestrian games during the Melbourne Olympics is a special case, which GPT, Gemini and Kimi pointed out in a side note. Some models seem to have old training material, and for example Grok assumes the current year is 2024. All models that accounted for awarded future Olympics (e.g. Los Angeles 2028) marked them clearly as upcoming. Overall I would judge that only GPT and MinMax gave incomplete answers, while all other models replied as the best humans could reasonably have.

2. If EUR/USD continues to slide to 1.5 by mid-2026, what is the likely effect on BMW s stock price by end of 2026? This question requires mapping the currency exchange rate to historic value, dodging the misleading word slide , and reasoning on where the revenue of a company comes from and how a weaker US dollar affects it in multiple ways. I ve frequently witnessed flagship models get it wrong how interest rates and exchange rates work. Apparently the binary choice between up or down is somehow challenging to the internal statistical model in the LLMs on a topic where there are a lot of training material that talk about both things being likely to happen, and choosing between them requires specifically reasoning about the scenario at hand and disregarding general knowledge of the situation. However, this time all the models concluded correctly that a weak dollar would have a negative overall effect on the BMW stock price. Gemini, GLM, Qwen and Kimi also mention the potential hedging effect of BMW s X-series production in South Carolina for worldwide export.

3. What is the Unicode code point for the traffic cone emoji? This was the first question where the the flagship models clearly still struggle in 2026. The trap here is that there is no traffic cone emoji, so an advanced model should simply refuse to give any Unicode numbers at all. Most LLMs however have an urge to give some answer, leading to hallucinations. Also, as the answer has a graphical element to it, the LLM might not understand how the emoji looks in ways that would be obvious to a human, and thus many models claim the construction sign emoji is a traffic cone, which it is not. By far the worst response was from GPT, that simply hallucinates and stops there: OpenAIs GPT-5.2 completely wrong answer to traffic cone emoji question While Gemini and Grok were among the three models not falling into this trap, the response from Claude was exemplary good: Claude Opus 4.6 exemplary good answer to traffic cone emoji question

4. Which languages are the 10 most commonly spoken in the world? For each language, count from 1 to 5. This seemingly simple question can become quite complex when you account for the fact that other languages might also have their own character system, both for words and the numerals (e.g. Arabic /one vs /1), and that numbers might have variations depending on what the thing being counted is (e.g in French object gender un/une), or whether plain numbers and occurrences have their own words (e.g. Russian /odin vs /raz). I ve also witnessed older models frequently mix up on what parts of the reply should be using what language. For a human this question is trivial, assuming they know the language. For LLMs it is surprisingly challenging. Grok and MinMax only gave a list of the most popular languages and stopped there without showing any words in the languages. Qwen got a bit further by trying to list numbers in each language, but the lists were only the numbers 1 to 5: Qwen3.5 Plus count to five in top 10 languages I have seen Grok do something similar before, which in fact inspired me to include this question in my mini-benchmark. GPT got a bit further, but for Hindi, Arabic and Bengali it listed the numerals in local script, not the number words. Gemini, GLM and Kimi gave a complete and correct answer as a list, while the absolute best answer and presentation was by Claude, that gave the table below:
Claude Opus 4.6 10 Most Commonly Spoken Languages (by Total Speakers)
# Language 1 2 3 4 5
1 English One Two Three Four Five
2 Mandarin Chinese (y ) ( r) (s n) (s ) (w )
3 Hindi (ek) (do) (t n) (ch r) (p ch)
4 Spanish Uno Dos Tres Cuatro Cinco
5 French Un Deux Trois Quatre Cinq
6 Arabic (w id) (ithn n) (thal tha) (arba a) (khamsa)
7 Bengali (ek) (dui) (tin) (ch r) (p ch)
8 Portuguese Um Dois Tr s Quatro Cinco
9 Russian (odin) (dva) (tri) (chetyre) (pyat')
10 Japanese (ichi) (ni) (san) (shi) (go)
Note: Rankings are based on estimated total speakers (native + non-native). Rankings can vary depending on the source and methodology used.

5. Count the number of drone launch pads in the picture. Together with the question, I uploaded this picture: Drone pad picture attached to question above A human can easily count that there are 10 rows and 30+ columns in the grid, but because the picture resolution isn t good enough, the exact number of columns can t be counted, and the answer should be that there are at least 300 launch pads in the picture. GPT and Grok both guessed the count is zero. Instead of hallucinating some number they say zero, but it would have been better to not give any number at all, and just state that they are unable to perform the task. Gemini gave as its answer 101 , which is quite odd, but reading the reasoning section, it seems to have tried counting items in the image without reasoning much about what it is actually counting and that there is clearly a grid that can make the counting much easier. Both Qwen and Kimi state they can see four parallel structures, but are unable to count drone launch pads. The absolutely best answer was given by Claude, which counted 10-12 rows and 30-40+ columns, and concluded that there must be 300-500 drone launch pads. Very close to best human level - impressive! This question applied only to multi-modal models that can see images, so GLM and MinMax could not give any response.

6. Explain why I am getting the error below, and what is the best way to fix it? Together with the question above, I gave this code block:
$ SH_SCRIPTS="$(mktemp; grep -Irnw debian/ -e '^#!.*/sh'   sort -u   cut -d ':' -f 1   true)"
$ shellcheck -x --enable=all --shell=sh "$SH_SCRIPTS"
/tmp/tmp.xQOpI5Nljx
debian/tests/integration-tests: /tmp/tmp.xQOpI5Nljx
debian/tests/integration-tests: openBinaryFile: does not exist (No such file or directory)
Older models would easily be misled by the last error message thinking that a file went missing, and focus on suggesting changes to the complex-looking first line. In reality the error is simply caused by having the quotes around the $SH_SCRIPTS, resulting in the entire multi-line string being passed as a single argument to shellcheck. So instead of receiving two separate file paths, shellcheck tries to open one file literally named /tmp/tmp.xQOpI5Nljx\ndebian/tests/integration-tests. Incorrect argument expansion is fairly easy for an experienced human programmer to notice, but tricky for an LLM. Indeed, Grok, MinMax, and Qwen fell for this trap and focused on the mktemp, assuming it somehow fails to create a file. Interestingly GLM fails to produce an answer at all, as the reasoning step seems to be looping, thinking too much about the missing file, but not understanding why it would be missing when there is nothing wrong with how mktemp is executed. Claude, Gemini, and Kimi immediately spot the real root cause of passing the variable quoted and suggested correct fixes that involve either removing the quotes, or using Bash arrays or xargs in a way that makes the whole command also handle correctly filenames with spaces in them.

Conclusion
Model Sports Economics Emoji Languages Visual Shell Score
Claude Opus 4.6 6/6
GPT-5.2 ~ 2.5/6
Grok 4.1 3/6
Gemini 3.1 Pro 5/6
GLM 5 ? N/A 3/5
MinMax M2.5 N/A 1/5
Qwen3.5 Plus ~ 2.5/6
Kimi K2.5 4/6
Obviously, my mini-benchmark only had 6 questions, and I ran it only once. This was obviously not scientifically rigorous. However it was systematic enough to trump just a mere feeling. The main finding for me personally is that Claude Opus 4.6, the flagship model by Anthropic, seems to give great answers consistently. The answers are not only correct, but also well scoped giving enough information to cover everything that seems relevant, without blurping unnecessary filler. I used Claude extensively in 2023-2024 when it was the main model available at my day work, but for the past year I had been using other models that I felt were better at the time. Now Claude seems to be the best-of-the-best again, with Gemini and Kimi as close follow-ups. Comparing their pricing at OpenRouter.ai the Kimi K2.5 price of $0.6 / million tokens is almost 90% cheaper than the Claude Opus 4.6 s $5.0 / million tokens suggests that Kimi K2.5 offers the best price-per-performance ratio. Claude might be cheaper with a monthly subscription directly from Anthropic, potentially narrowing the price gap. Overall I do feel that Anthropic, Google and Moonshot.ai have been pushing the envelope with their latest models in a way that one can t really claim that AI models have plateaued. In fact, one could claim that at least Claude has now climbed over the hill of AI slop and consistently produces valuable results. If and when AI usage expands from here, we might actually not drown in AI slop as chances of accidentally crappy results decrease. This makes me positive about the future. I am also really happy to see that there wasn t just one model crushing everybody else, but that there are at least three models doing very well. As an open source enthusiast I am particularly glad to see that Moonshot.ai s Kimi K2.5 is published with an open license. Given the hardware, anyone can run it on their own. OpenRouter.ai currently lists 9 independent providers alongside Moonshot.ai itself, showcasing the potential of open-weight models in practice. If the pattern holds and flagship models continue improving at this pace we might look back at 2026 as the year AI stopped feeling like a call center associate and started to resemble a scientific researcher. While new models become available we need to keep testing, keep questioning, and keep our expectations grounded in actual performance rather than press releases. Thanks to OpenRouter.ai for providing a great service that makes testing various models incredibly easy!

21 February 2026

Thomas Goirand: Seamlessly upgrading a production OpenStack cluster in 4 hours : with 2k lines shell script


tl;dr: To the question: what does it take to upgrade OpenStack , my personal answer is: less than 2K lines of dash script. I ll here describe its internals, and why I believe it is the correct solution. Why writing this blog post During FOSSDEM 2024, I was asked how to you handle upgrades . I answered with a big smile and a short with a very small shell script as I couldn t explain in 2 minutes how it was done. Just saying it is great this way doesn t help giving readers enough hints to be trusted. Why and how did I do it the right way ? This blog post is an attempt to reply better to this question more deeply. Upgrading OpenStack in production I wrote this script maybe a 2 or 3 years ago. Though I m only blogging about it today, because I did such an upgrade in a public cloud in production last Thuesday evening (ie: the first region of the Infomaniak public cloud). I d say the cluster is moderately large (as of today: about 8K+ VMs running, 83 compute nodes, 12 network nodes, for a total of 10880 physical CPU cores and 125 TB of RAM if I only count the compute servers). It took only 4 hours to do the upgrade (though I already wore some more code to speed this up for the next time ). It went super smooth without a glitch. I mostly just sat, reading the script output and went to bed once it finished running. The next day, all my colleagues at Infomaniak were nicely congratulating me that it went that smooth (a big thanks to all of you who did). I couldn t dream of an upgrade that smooth! :) Still not impressed? Boring read? Yeah let s dive into more technical details. Intention behind the implementation My script isn t perfect. I wont ever pretend it is. But at least, it does minimize down time of every OpenStack service. It also is a by the book implementation of what s written in the OpenStack doc, following every upstream advice. As a result, it is fully seamless for some OpenStack services, and as HA as OpenStack can be for others. The upgrade process is of course idempotent and can be re-run in case of failure. Here s why. General idea My upgrade script does thing in a certain order, respecting what is documented about upgrades in the OpenStack documentation. It basically does: Installing dependencies The first thing the upgrade script does is: For this last thing, a static list of all needed dependency upgrade is maintained between each release of OpenStack, and for each type of nodes. Then for all packages in this list, the script checks with dpkg-query that the package is really installed, and with apt-cache policy that it really is going to be upgraded (Maybe there s an easier way to do this?). This way, no package is marked as manually installed by mistake during the upgrade process. This ensure that apt-get purge autoremove really does what it should, and that the script is really idempotent. The idea then, is that once all dependencies are installed, upgrading and restarting leaf packages (ie: OpenStack services like Nova, Glance, Cinder, etc.) is very fast, because the apt-get command doesn t need to install all dependencies. So at this point, doing apt-get install python3-cinder for example (which will also, thanks to dependencies, upgrade cinder-api and cinder-scheduler, if it s in a controller node) only takes a few seconds. This principle applies to all nodes (controller nodes, network nodes, compute nodes, etc.), which helps a lot speeding-up the upgrade and reduce unavailability. hapc At its core, the oci-cluster-upgrade-openstack-release script uses haproxy-cmd (ie: /usr/bin/hapc) to drain each API server to-be-upgraded from haproxy. Hapc is a simple Python wrapper around the haproxy admin socket: it sends command to it with an easy to understand CLI. So it is possible to reliably upgrade one API service only after it s drained away. Draining means one just wait for the last query to finish and the client to disconnect from http before giving the backend server some more queries. If you do not know hapc / haproxy-cmd, I recommend trying it: it s going to be hard for you to stop using it once you tested it. Its bash-completion script makes it VERY easy to use, and it is helpful in production. But not only: it is also nice to have when writing this type of upgrade script. Let s dive into haproxy-cmd. Example on how to use haproxy-cmd Let me show you. First, ssh one of the 3 controller and search where the virtual IP (VIP) is located with crm resource locate openstack-api-vip or with a (more simple) crm status . Let s ssh that server who got the VIP, and now, let s drain it away from haproxy. $ hapc list-backends
$ hapc drain-server --backend glancebe --server cl1-controller-1.infomaniak.ch --verbose --wait --timeout 50
$ apt-get install glance-api
$ hapc enable-server --backend glancebe --server cl1-controller-1.infomaniak.ch
Upgrading the control plane My upgrade script leverages hapc just like above. For each OpenStack project, it s done in this order on the first node holding the VIP: Starting at [1], the risk is that other nodes may have a new version of the database schema, but an old version of the code that isn t compatible with it. But it doesn t take long, because the next step is to take care of the other (usually 2) nodes of the OpenStack control plane: So while there s technically zero down time, still some issues between [1] and [2] above may happen because of the new DB schema and the old code (both for API and other services) are up and running at the same time. It is however supposed to be rare cases (some OpenStack project don t even have db change between some OpenStack releases, and it often continues to work on most queries with the upgraded db), and the cluster will be like that for a very short time, so that s fine, and better than an full API down time. Satellite services Then there s satellite services, that needs to be upgraded. Like Neutron, Nova, Cinder. Nova is the least offender as it has all the code to rewrite Json object schema on-the-fly so that it continues to work during an upgrade. Though it s a known issue that Cinder doesn t have the feature (last time I checked), and it s also probably the same for Neutron (maybe recent-ish versions of OpenStack do use oslo.versionnedobjects ?). Anyways, upgrade on these nodes are done just right after the control plane for each service. Parallelism and upgrade timings As we re dealing with potentially hundreds of nodes per cluster, a lot of operations are performed in parallel. I choose to simply use the & shell thingy with some wait shell stuff so that not too many jobs are done in parallel. For example, when disabling SSH on all nodes, this is done 24 nodes at a time. Which is fine. And the number of nodes is all depending on the type of thing that s being done. For example, while it s perfectly OK to disable puppet on 24 nodes at the same time, but it is not OK to do that with Neutron services. In fact, each time a Neutron agent is restarted, the script explicitly waits for 30 seconds. This conveniently avoids a hailstorm of messages in RabbitMQ, and neutron-rpc-server to become too busy. All of these waiting are necessary, and this is one of the reasons why can sometimes take that long to upgrade a (moderately big) cluster. Not using config management tooling Some of my colleagues would have prefer that I used something like Ansible. Whever, there s no reason to use such tool if the idea is just to perform some shell script commands on every servers. It is a way more efficient (in terms of programming) to just use bash / dash to do the work. And if you want my point of view about Ansible: using yaml for doing such programming would be crasy. Yaml is simply not adapted for a job where if, case, and loops are needed. I am well aware that Ansible has workarounds and it could be done, but it wasn t my choice.

19 February 2026

Peter Pentchev: Ringlet release: fnmatch-regex 0.3.0

Version 0.3.0 of the fnmatch-regex Rust crate is now available. The major new addition is the glob_to_regex_pattern function that only converts the glob pattern to a regular expression one without building a regular expression matcher. Two new features - regex and std - are also added, both enabled by default. For more information, see the changelog at the homepage.

17 February 2026

Freexian Collaborators: Monthly report about Debian Long Term Support, January 2026 (by Santiago Ruano Rinc n)

The Debian LTS Team, funded by Freexian s Debian LTS offering, is pleased to report its activities for January.

Activity summary During the month of January, 20 contributors have been paid to work on Debian LTS (links to individual contributor reports are located below). The team released 33 DLAs fixing 216 CVEs. The team continued preparing security updates in its usual rhythm. Beyond the updates targeting Debian 11 ( bullseye ), which is the current release under LTS, the team also proposed updates for more recent releases (Debian 12 ( bookworm ) and Debian 13 ( trixie )), including Debian unstable. We highlight several notable security updates here below. Notable security updates:
  • python3.9, prepared by Andrej Shadura (DLA-4455-1), fixing multiple vulnerabilities in the Python interpreter.
  • php, prepared by Guilhem Moulin (DLA-4447-1), fixing two vulnerabilities that could yield to request forgery or denial of service.
  • apache2, prepared by Bastien Roucari s DLA-4452-1, fixing four CVEs.
  • linux-6.1, prepared by Ben Hutchings (DLA-4436-1), as a regular update of the linux 6.1 backport to Debian 11.
  • python-django, prepared by Chris Lamb (DLA-4458-1), resolving multiple vulnerabilities.
  • firefox-esr prepared by Emilio Pozuelo Monfort (DLA-4439-1)
  • gnupg2, prepared by Roberto S nchez (DLA-4437-1), fixing multiple issues, including CVE-2025-68973 that could potentially be exploited to execute arbitrary code.
  • apache-log4j2, prepared by Markus Koschany (DLA-4444-1)
  • ceph, prepared by Utkarsh Gupta (DLA-4460-1)
  • inetutils, prepared by Andreas Henriksson (DLA-4453-1), fixing an authentication bypass in telnetd.
Moreover, Sylvain Beucler studied the security support status of p7zip, a fork of 7zip that has become unmaintained upstream. To avoid letting the users continue using an unsupported package, Sylvain has investigated a path forward in collaboration with the security team and the 7zip maintainer, looking to replace p7zip with 7zip. It is to note however that 7zip developers don t reveal the information about the patches that fix CVEs, making it difficult to backport single patches to fix vulnerabilities in Debian released versions. Contributions from outside the LTS Team: Thunderbird, prepared by maintainer Christoph Goehre. The DLA (DLA-4442-1) was published by Emilio. The LTS Team has also contributed with updates to the latest Debian releases:
  • Bastien uploaded gpsd to unstable, and proposed updates for trixie #1126121 and bookworm #1126168 to fix two CVEs.
  • Bastien also prepared the imagemagick updates for trixie and bookworm, released as DSA-6111-1, along with the bullseye update DLA-4448-1.
  • Chris proposed a trixie point update for python-django (#112646), and the work for bookworm was completed in February (#1079454). The longstanding bookworm update required tracking down a regression in the django-storages packages.
  • Markus prepared tomcat10 updates for trixie and bookworm (DSA-6120-1), and tomcat11 for trixie (DSA-6121-1)
  • Thorsten Alteholz prepared bookworm point updates for zvbi (#1126167) to fix five CVEs; taglib (#1126273) to fix one CVE; and libuev (#1126370) to fix one CVE.
  • Utkarsh prepared an unstable update of node-lodash to fix one CVE.
Other than the work related to updates, Sylvain made several improvements to the documentation and tooling used by the team.

Individual Debian LTS contributor reports

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31 January 2026

Russ Allbery: Review: Dragon Pearl

Review: Dragon Pearl, by Yoon Ha Lee
Series: Thousand Worlds #1
Publisher: Rick Riordan Presents
Copyright: 2019
ISBN: 1-368-01519-0
Format: Kindle
Pages: 315
Dragon Pearl is a middle-grade space fantasy based on Korean mythology and the first book of a series. Min is a fourteen-year-old girl living on the barely-terraformed world of Jinju with her extended family. Her older brother Jun passed the entrance exams for the Academy and left to join the Thousand Worlds Space Forces, and Min is counting the years until she can do the same. Those plans are thrown into turmoil when an official investigator appears at their door claiming that Jun deserted to search for the Dragon Pearl. A series of impulsive fourteen-year-old decisions lead to Min heading for a spaceport alone, determined to find her brother and prove his innocence. This would be a rather improbable quest for a young girl, but Min is a gumiho, one of the supernaturals who live in the Thousand Worlds alongside non-magical humans. Unlike the more respectable dragons, tigers, goblins, and shamans, gumiho are viewed with suspicion and distrust because their powers are useful for deception. They are natural shapeshifters who can copy the shapes of others, and their Charm ability lets them influence people's thoughts and create temporary illusions of objects such as ID cards. It will take all of Min's powers, and some rather lucky coincidences, to infiltrate the Space Forces and determine what happened to her brother. It's common for reviews of this book to open with a caution that this is a middle-grade adventure novel and you should not expect a story like Ninefox Gambit. I will be boring and repeat that caution. Dragon Pearl has a single first-person viewpoint and a very linear and straightforward plot. Adult readers are unlikely to be surprised by plot twists; the fun is the world-building and seeing how Min manages to work around plot obstacles. The world-building is enjoyable but not very rigorous. Min uses and abuses Charm with the creative intensity of a Dungeons & Dragons min-maxer. Each individual event makes sense given the implication that Min is unusually powerful, but I'm dubious about the surrounding society and lack of protections against Charm given what Min is able to do. Min does say that gumiho are rare and many people think they're extinct, which is a bit of a fig leaf, but you'll need to bring your urban fantasy suspension of disbelief skills to this one. I did like that the world-building conceit went more than skin deep and influenced every part of the world. There are ghosts who are critical to the plot. Terraforming is done through magic, hence the quest for the Dragon Pearl and the miserable state of Min's home planet due to its loss. Medical treatment involves the body's meridians, as does engineering: The starships have meridians similar to those of humans, and engineers partly merge with those meridians to adjust them. This is not the sort of book that tries to build rigorous scientific theories or explain them to the reader, and I'm not sure everything would hang together if you poked at it too hard, but Min isn't interested in doing that poking and the story doesn't try to justify itself. It's mostly a vibe, but it's a vibe that I enjoyed and that is rather different than other space fantasy I've read. The characters were okay but never quite clicked for me, in part because proper character exploration would have required Min take a detour from her quest to find her brother and that was not going to happen. The reader gets occasional glimpses of a military SF cadet story and a friendship on false premises story, but neither have time to breathe because Min drops any entanglement that gets in the way of her quest. She's almost amoral in a way that I found believable but not quite aligned with my reading mood. I also felt a bit wrong-footed by how her friendships developed; saying too much more would be a spoiler, but I was expecting more human connection than I got. I think my primary disappointment with this book was something I knew going in, not in any way its fault, and part of the reason why I'd put off reading it: This is pitched at young teenagers and didn't have quite enough plot and characterization complexity to satisfy me. It's a linear, somewhat episodic adventure story with some neat world-building, and it therefore glides over the spots where an adult novel would have added political and factional complexity. That is exactly as advertised, so it's up to you whether that's the book you're in the mood for. One warning: The text of this book opens with an introduction by Rick Riordan that is just fluff marketing and that spoils the first few chapters of the book. It is unmarked as such at the beginning and tricked me into thinking it was the start of the book proper, and then deeply annoyed me. If you do read this book, I recommend skipping the utterly pointless introduction and going straight to chapter one. Followed by Tiger Honor. Rating: 6 out of 10

3 January 2026

Louis-Philippe V ronneau: 2025 A Musical Retrospective

2026 already! The winter weather here has really been beautiful and I always enjoy this time of year. Writing this yearly musical retrospective has now become a beloved tradition of mine1 and I enjoy retracing the year's various events through albums I listened to and concerts I went to. Albums In 2025, I added 141 new albums to my collection, around 60% more than last year's haul. I think this might have been too much? I feel like I didn't have time to properly enjoy all of them and as such, I decided to slow down my acquisition spree sometimes in early December, around the time I normally do the complete opposite. This year again, I bought the vast majority of my music on Bandcamp. Most of the other albums I bought as CDs and ripped them. Concerts In 2025, I went to the following 25 (!!) concerts: Although I haven't touched metalfinder's code in a good while, my instance still works very well and I get the occasional match when a big-name artist in my collection comes in town. Most the venues that advertise on Bandsintown are tied to Ticketmaster though, which means most underground artists (i.e. most of the music I listen to) end up playing elsewhere. As such, shout out again to the Gancio project and to the folks running the Montreal instance. It continues to be a smash hit and most of the interesting concerts end up being advertised there. See you all in 2026!

  1. see the 2022, 2023 and 2024 entries

31 December 2025

kpcyrd: 2025 wrapped

Same as last year, this is a summary of what I ve been up to throughout the year. See also the recap/retrospection published by my friends (antiz, jvoisin, orhun). Thanks to everybody who has been part of my human experience, past or present. Especially those who ve been closest.

16 December 2025

Freexian Collaborators: Debusine repositories now in beta (by Colin Watson)

We re happy to announce that Debusine can now be used to maintain APT-compatible add-on package repositories for Debian. This facility is available in public beta to Debian developers and maintainers.

Why? Debian developers typically put most of their effort towards maintaining the main Debian archive. However, it s often useful to have other places to work, for various reasons:
  • Developers working on a set of packages might need to check that changes to several of them all work properly together on a real system.
  • Somebody fixing a bug might need to ask affected users to test the fix before uploading it to Debian.
  • Some projects are difficult to package in a way that meets Debian policy, or are too niche to include in Debian, but it s still useful to distribute them in a packaged form.
  • For some packages, it s useful to provide multiple upstream versions for multiple Debian releases, even though Debian itself would normally want to keep that to a minimum.
The Ubuntu ecosystem has had PPAs for a long time to meet these sorts of needs, but people working directly on Debian have had to make do with putting things together themselves using something like reprepro or aptly. Discussions about this have been happening for long enough that people started referring to PPAs for Debian as bikesheds , and users often find themselves trying to use Ubuntu PPAs on Debian systems and hoping that dependencies will be compatible enough for things to more or less work. This clearly isn t ideal, and solving it is one of Freexian s objectives for Debusine. Developers publishing packages to Debusine repositories can take advantage of all Debusine s existing facilities, including a battery of QA tests and regression tracking (coming soon). Repositories are signed using per-repository keys held in Debusine s signing service, and uploads to repositories are built against the current contents of that repository as well as the corresponding base Debian release. All repositories include automatic built-in snapshot capabilities.

Who can use this service? We ve set up debusine.debian.net to allow using repositories. All Debian Developers and Debian Maintainers can log in there and publish packages to it. The resulting repositories are public by default. debusine.debian.net only allows packages with licences that allow distribution by Debian, and it is intended primarily for work that could reasonably end up in Debian; Freexian reserves the right to remove repositories from it.

How can I use it? If you are a Debian contributor, we d be very excited to have you try this out, especially if you give us feedback. We have published instructions for developers on using this. Since this is a beta service, you can expect things to change, but we ll maintain compatibility where we can. If you re interested in using this in a commercial setting, please contact Freexian to discuss what we can do for you.

17 November 2025

Valhalla's Things: Historically Inaccurate Hemd

Posted on November 17, 2025
Tags: madeof:atoms, craft:sewing
A woman wearing a white shirt with a tall, thick collar with lines of blue embroidery, closed in the front with small buttons; the sleeves are wide and billowing, gathered at the cuffs with more blue embroidery. She's keeping her hands at the waist so that the shirt, which reaches to mid thigh, doesn't look like a shapeless tent from the neck down. After cartridge pleating and honeycombing, I was still somewhat in the mood for that kind of fabric manipulation, and directing my internet searches in that vague direction, and I stumbled on this: https://katafalk.wordpress.com/2012/06/26/patternmaking-for-the-kampfrau-hemd-chemise/ Now, do I want to ever make myself a 16th century German costume, especially a kampfrau one? No! I m from lake Como! Those are the enemies who come down the Alps pillaging and bringing the Black Death with them! Although I have to admit that at times during my day job I have found the idea of leaving everything to go march with the J germonsters attractive. You know, the exciting prospective of long days of march spent knitting sturdy socks, punctuated by the excitement of settling down in camp and having a chance of doing lots of laundry. Or something. Sometimes being a programmer will make you think odd things. Anyway, going back to the topic, no, I didn t need an historically accurate hemd. But I did need a couple more shirts for daily wear, I did want to try my hand at smocking, and this looked nice, and I was intrigued by the way the shaping of the neck and shoulder worked, and wondered how comfortable it would be. And so, it had to be done. I didn t have any suitable linen, but I did have quite a bit of cotton voile, and since I wasn t aiming at historical accuracy it looked like a good option for something where a lot of fabric had to go in a small space. At first I considered making it with a bit less fabric than the one in the blog, but then the voile was quite thin, so I kept the original measurement as is, only adapting the sleeve / sides seams to my size. The same woman, from the back. This time the arms are out, so that the big sleeves show better, but the body does look like a tent. With the pieces being rectangles the width of the fabric, I was able to have at least one side of selvedge on all seams, and took advantage of it by finishing the seams by simply folding the allowances to one sides so that the selvedge was on top, and hemstitching them down as I would have done with a folded edge when felling. Also, at first I wanted to make the smocking in white on white, but then I thought about a few hanks of electric blue floss I had in my stash, and decided to just go with it. The initial seams were quickly made, then I started the smocking at the neck, and at that time the project went on hold while I got ready to go to DebConf. Then I came back and took some time to get back into a sewing mood, but finally the smocking on the next was finished, and I could go on with the main sewing, which, as I expected, went decently fast for a handsewing project. detail of the smocking in progress on the collar, showing the lines of basting thread I used as a reference, and the two in progress zig-zag lines being worked from each side. While doing the diagonal smocking on the collar I counted the stitches to make each side the same length, which didn t completely work because the gathers weren t that regular to start with, and started each line from the two front opening going towards the center back, leaving a triangle with a different size right in the middle. I think overall it worked well enough. Then there were a few more interruptions, but at last it was ready! just as the weather turned cold-ish and puffy shirts were no longer in season, but it will be there for me next spring. I did manage to wear it a few times and I have to say that the neck shaping is quite comfortable indeed: it doesn t pull in odd ways like the classical historically accurate pirate shirt sometimes does, and the heavy gathering at the neck makes it feel padded and soft. The same shirt belted (which looks nicer); one hand is held out to show that the cuff is a bit too wide and falls down over the hand. I m not as happy with the cuffs: the way I did them with just honeycombing means that they don t need a closure, and after washing and a bit of steaming they lie nicely, but then they tend to relax in a wider shape. The next time I think I ll leave a slit in the sleeves, possibly make a different type of smocking (depending on whether I have enough fabric) and then line them like the neck so that they are stable. Because, yes, I think that there will be another time: I have a few more project before that, and I want to spend maybe another year working from my stash, but then I think I ll buy some soft linen and make at least another one, maybe with white-on-white smocking so that it will be easier to match with different garments.

3 November 2025

Russ Allbery: Review: The Raven Scholar

Review: The Raven Scholar, by Antonia Hodgson
Series: Eternal Path Trilogy #1
Publisher: Orbit
Copyright: April 2025
ISBN: 0-316-57723-5
Format: Kindle
Pages: 651
The Raven Scholar is an epic fantasy and the first book of a projected trilogy. It is Antonia Hodgson's first published fantasy novel; her previous published novels are historical mystery. I would classify this as adult fantasy the main character is thirty-four with a stable court position but it has strong YA vibes because of the generational turnover feel of the main plot. Eight years before the start of this book, Andren Valit attempted to assassinate the emperor and failed. Since then, his widow and three children twins Yana and Ruko and infant Nisthala have been living in disgrace in a cramped apartment, subject to constant inspections and suspicion. As the story opens, they have been summoned to appear before the emperor, escorted by a young and earnest Hound (essentially the state security services) named Shal Worthy. The resulting interrogation is full of dangerous traps. Not all of them will be avoided. The formalization of the consequences of that imperial summons falls to an unpopular Junior Archivist (Third Class) whose one notable skill is her penmanship. A meeting that was disasterous for the Valits becomes unexpectedly fortunate for the archivist, albeit with a poisonous core. Eight years later, Neema Kraa is High Scholar, and Emperor Bersun's twenty-four years of permitted reign is coming to an end. The Festival is about to begin. One representative from each of the empire's eight anats (religious schools) will compete in seven days of Trials, save for the Dragons who do not want the throne and will send a proxy. The victor according to the Trials scoring system will become emperor and reign unquestioned for twenty-four years or until resignation. This is the system that put an end to the era of chaos and has been in place for over a thousand years. On the eve of the Trials, the Raven contender is found murdered. Neema is immediately a suspect; she even has reasons to suspect herself. She volunteers to lead the investigation because she has to know what happened. She is also volunteered to be the replacement Raven contender. There is no chance that she will become emperor; she doesn't even know how to fight. But agnostic Neema has a rather unexpected ally.
As the last chime fades we drop neatly on to the balcony's rusting hand rail, folding our wings with a soft shuffle. Noon, on the ninth day of the eighth month, 1531. Neema Kraa's lodgings. We are here, exactly where we should be, at exactly the right moment, because we are the Raven, and we are magnificent.
The Raven Scholar is a rather good epic fantasy, with some caveats that I'll get to in a moment, but I found it even more fascinating as a genre artifact. I've read my share of epic fantasy over the years, although most of my familiarity of the current wave of new adult fairy epics comes from reviews rather than personal experience. The Raven Scholar is epic fantasy, through and through. There is court intrigue, a main character who is a court functionary unexpectedly thrown into the middle of some problem, civilization-wide stakes, dramatic political alliances, detailed magic and mythological systems, and gods. There were moments that reminded me of a Guy Gavriel Kay novel, although Hodgson's characters tend more towards disarming moments of humanization instead of Kay's operatic scenes of emotional intensity. But The Raven Scholar is also a murder mystery, complete with a crime scene, clues, suspects, evidence, an investigation, a possibly compromised detective, and a morass of possible motives and red herrings. I'm not much of a mystery reader, but this didn't feel like sort of ancillary mystery that might crop up in the course of a typical epic fantasy. It felt like a full-fledged investigation with an amateur detective; one can tell that Hodgson's previous four books were historical mysteries. And then there's the Trials, which are the centerpiece of the book. This book helped me notice that people (okay, me, I'm the people) have been sleeping on the influence of The Hunger Games, Battle Royale, and reality TV (specifically Survivor) on genre fiction, possibly because the more obvious riffs on the idea (Powerless, The Selection) have been young adult or new adult. Once I started looking, I realized this idea is everywhere now: Throne of Glass, Fourth Wing, even The Night Circus to some extent. Competitions with consequences are having a moment. I suspect having a competition to decide the next emperor is going to strike some traditional fantasy readers as sufficiently absurd and unbelievable that it will kick them out of the book. I had a moment of "okay, this is weird, why would anyone stick with this system for so long" myself. But I would encourage such readers to interrogate whether that's only a response from unfamiliarity; after all, strange women lying in ponds distributing swords is no basis for a system of government either. This is hardly the most unrealistic epic fantasy trope, and it has the advantage of being a hell of a plot generator when handled well. Hodgson handles it well. Society in this novel is structured around the anats and the eight Guardians, gods who, according to myth, had returned seven times previously to save the world, but who will destroy the world when they return again. Each Guardian represents a group of characteristics and useful societal functions: the Ox is trustworthy, competent and hard-working; the Fox is a trickster and a rule-bender; the Raven is shrewd and careful and is the Guardian of scholars and lawyers. Each Trial is organized by one of the anats and tests the contenders for the skills most valued by that Guardian, often in subtle and rather ingenious ways. There are flaws here that you could poke at if you wanted to, but I was charmed and thoroughly entertained by how well Hodgson weaves the story around the Trials and uses the conflicting values to create character conflict, unexpected alliances, and engrossing plot. Most importantly for a book of this sort, I liked Neema. She has a charming combination of competence, quirks (she is almost physically unable to not correct people's factual errors), insecurity, imposter syndrome, and determination. She is way out of her depth and knows it, but she has an ethical core and an insatiable curiosity that won't let her leave the central mysteries of the book alone. And the character dynamics are great; there are a lot of characters, including the competition problem of having to juggle eight contenders and give them all sufficient characterization to be meaningful, but this book uses its length to give each character some room to breathe. This is a long book, well over 600 pages, but it felt packed with events and plot twists. After every chapter I had to fight the urge to read just one more. The biggest drawback of this book is that it is very much the first book of a trilogy, none of the other volumes are out yet, and the ending is rather nasty. This is the sort of trilogy that opens with a whole lot of bad things happening, and while I am thoroughly hooked and will purchase the next volume as soon as it's available, I wish Hodgson had found a way to end the book on a somewhat more positive or hopeful note. The middle of the book was great; the end was a bit of an emotional slog, alas. The writing is good enough here that I'm fairly sure the depression will be worth it, but if you need your endings to be triumphant (and who could blame you in this moment in history), you may want to wait on this one until more volumes are out. Apart from that, though, this was a lot of fun. The Guardians felt like they came from a different strand of fantasy than you usually see in epic, more of a traditional folk tale vibe, which adds an intriguing twist to the epic fantasy setting. The characters all work, and Hodgson even pulls off some Game of Thrones style twists that make you sympathetic to characters you previously hated. The magic system apart from the Guardians felt underbaked, but the politics had more depth than a lot of fantasy novels. If you want the truly complex and twisty politics you would get from one of Guy Gavriel Kay's historical rewrites, you will come away disappointed, but it was good enough for me. And I did enjoy the Raven.
Respect, that's all we demand. Recognition of our magnificence. Offerings. Love. Fear. Trembling awe. Worship. Shiny things. Blood sacrifice, some of us very much enjoy blood sacrifice. Truly, we ask for so little.
Followed by an as-yet untitled sequel that I hope will materialize. Rating: 7 out of 10

10 October 2025

Sergio Cipriano: Avoiding 5XX errors by adjusting Load Balancer Idle Timeout

Avoiding 5XX errors by adjusting Load Balancer Idle Timeout Recently I faced a problem in production where a client was running a RabbitMQ server behind the Load Balancers we provisioned and the TCP connections were closed every minute. My team is responsible for the LBaaS (Load Balancer as a Service) product and this Load Balancer was an Envoy proxy provisioned by our control plane. The error was similar to this:
[2025-10-03 12:37:17,525 - pika.adapters.utils.connection_workflow - ERROR] AMQPConnector - reporting failure: AMQPConnectorSocketConnectError: timeout("TCP connection attempt timed out: ''/(<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_STREAM: 1>, 6, '', ('<IP>', 5672))")
[2025-10-03 12:37:17,526 - pika.adapters.utils.connection_workflow - ERROR] AMQP connection workflow failed: AMQPConnectionWorkflowFailed: 1 exceptions in all; last exception - AMQPConnectorSocketConnectError: timeout("TCP connection attempt timed out: ''/(<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_STREAM: 1>, 6, '', ('<IP>', 5672))"); first exception - None.
[2025-10-03 12:37:17,526 - pika.adapters.utils.connection_workflow - ERROR] AMQPConnectionWorkflow - reporting failure: AMQPConnectionWorkflowFailed: 1 exceptions in all; last exception - AMQPConnectorSocketConnectError: timeout("TCP connection attempt timed out: ''/(<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_STREAM: 1>, 6, '', ('<IP>', 5672))"); first exception - None
At first glance, the issue is simple: the Load Balancer's idle timeout is shorter than the RabbitMQ heartbeat interval. The idle timeout is the time at which a downstream or upstream connection will be terminated if there are no active streams. Heartbeats generate periodic network traffic to prevent idle TCP connections from closing prematurely. Adjusting these timeout settings to align properly solved the issue. However, what I want to explore in this post are other similar scenarios where it's not so obvious that the idle timeout is the problem. Introducing an extra network layer, such as an Envoy proxy, can introduce unpredictable behavior across your services, like intermittent 5XX errors. To make this issue more concrete, let's look at a minimal, reproducible setup that demonstrates how adding an Envoy proxy can lead to sporadic errors.

Reproducible setup I'll be using the following tools: This setup is based on what Kai Burjack presented in his article. Setting up Envoy with Docker is straightforward:
$ docker run \
    --name envoy --rm \
    --network host \
    -v $(pwd)/envoy.yaml:/etc/envoy/envoy.yaml \
    envoyproxy/envoy:v1.33-latest
I'll be running experiments with two different envoy.yaml configurations: one that uses Envoy's TCP proxy, and another that uses Envoy's HTTP connection manager. Here's the simplest Envoy TCP proxy setup: a listener on port 8000 forwarding traffic to a backend running on port 8080.
static_resources:
  listeners:
  - name: go_server_listener
    address:
      socket_address:
        address: 0.0.0.0
        port_value: 8000
    filter_chains:
    - filters:
      - name: envoy.filters.network.tcp_proxy
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.tcp_proxy.v3.TcpProxy
          stat_prefix: go_server_tcp
          cluster: go_server_cluster
  clusters:
  - name: go_server_cluster
    connect_timeout: 1s
    type: static
    load_assignment:
      cluster_name: go_server_cluster
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address:
                address: 127.0.0.1
                port_value: 8080
The default idle timeout if not otherwise specified is 1 hour, which is the case here. The backend setup is simple as well:
package main

import (
    "fmt"
    "net/http"
    "time"
)

func helloHandler(w http.ResponseWriter, r *http.Request)  
  w.Write([]byte("Hello from Go!"))
 

func main()  
    http.HandleFunc("/", helloHandler)

    server := http.Server 
        Addr:        ":8080",
        IdleTimeout: 3 * time.Second,
     

    fmt.Println("Starting server on :8080")
    panic(server.ListenAndServe())
 
The IdleTimeout is set to 3 seconds to make it easier to test. Now, oha is the perfect tool to generate the HTTP requests for this test. The Load test is not meant to stress this setup, the idea is to wait long enough so that some requests are closed. The burst-delay feature will help with that:
$ oha -z 30s -w --burst-delay 3s --burst-rate 100 http://localhost:8000
I'm running the Load test for 30 seconds, sending 100 requests at three-second intervals. I also use the -w option to wait for ongoing requests when the duration is reached. The result looks like this: oha test report tcp fail We had 886 responses with status code 200 and 64 connections closed. The backend terminated 64 connections while the load balancer still had active requests directed to it. Let's change the Load Balancer idle_timeout to two seconds.
filter_chains:
- filters:
  - name: envoy.filters.network.tcp_proxy
    typed_config:
      "@type": type.googleapis.com/envoy.extensions.filters.network.tcp_proxy.v3.TcpProxy
      stat_prefix: go_server_tcp
      cluster: go_server_cluster
      idle_timeout: 2s # <--- NEW LINE
Run the same test again. oha test report tcp success Great! Now all the requests worked. This is a common issue, not specific to Envoy Proxy or the setup shown earlier. Major cloud providers have all documented it. AWS troubleshoot guide for Application Load Balancers says this: The target closed the connection with a TCP RST or a TCP FIN while the load balancer had an outstanding request to the target. Check whether the keep-alive duration of the target is shorter than the idle timeout value of the load balancer. Google troubleshoot guide for Application Load Balancers mention this as well: Verify that the keepalive configuration parameter for the HTTP server software running on the backend instance is not less than the keepalive timeout of the load balancer, whose value is fixed at 10 minutes (600 seconds) and is not configurable. The load balancer generates an HTTP 5XX response code when the connection to the backend has unexpectedly closed while sending the HTTP request or before the complete HTTP response has been received. This can happen because the keepalive configuration parameter for the web server software running on the backend instance is less than the fixed keepalive timeout of the load balancer. Ensure that the keepalive timeout configuration for HTTP server software on each backend is set to slightly greater than 10 minutes (the recommended value is 620 seconds). RabbitMQ docs also warn about this: Certain networking tools (HAproxy, AWS ELB) and equipment (hardware load balancers) may terminate "idle" TCP connections when there is no activity on them for a certain period of time. Most of the time it is not desirable. Most of them are talking about Application Load Balancers and the test I did was using a Network Load Balancer. For the sake of completeness, I will do the same test but using Envoy's HTTP connection manager. The updated envoy.yaml:
static_resources:
  listeners:
  - name: listener
    address:
      socket_address:
        address: 0.0.0.0
        port_value: 8000
    filter_chains:
    - filters:
      - name: envoy.filters.network.http_connection_manager
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
          stat_prefix: go_server_http
          access_log:
          - name: envoy.access_loggers.stdout
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.access_loggers.stream.v3.StdoutAccessLog
          http_filters:
          - name: envoy.filters.http.router
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router
          route_config:
            name: http_route
            virtual_hosts:
            - name: local_service
              domains: ["*"]
              routes:
              - match:
                  prefix: "/"
                route:
                  cluster: go_server_cluster
  clusters:
  - name: go_server_cluster
    type: STATIC
    load_assignment:
      cluster_name: go_server_cluster
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address:
                address: 0.0.0.0
                port_value: 8080
The yaml above is an example of a service proxying HTTP from 0.0.0.0:8000 to 0.0.0.0:8080. The only difference from a minimal configuration is that I enabled access logs. Let's run the same tests with oha. oha test report http fail Even thought the success rate is 100%, the status code distribution show some responses with status code 503. This is the case where is not that obvious that the problem is related to idle timeout. However, it's clear when we look the Envoy access logs:
[2025-10-10T13:32:26.617Z] "GET / HTTP/1.1" 503 UC 0 95 0 - "-" "oha/1.10.0" "9b1cb963-449b-41d7-b614-f851ced92c3b" "localhost:8000" "0.0.0.0:8080"
UC is the short name for UpstreamConnectionTermination. This means the upstream, which is the golang server, terminated the connection. To fix this once again, the Load Balancer idle timeout needs to change:
  clusters:
  - name: go_server_cluster
    type: STATIC
    typed_extension_protocol_options: # <--- NEW BLOCK
      envoy.extensions.upstreams.http.v3.HttpProtocolOptions:
        "@type": type.googleapis.com/envoy.extensions.upstreams.http.v3.HttpProtocolOptions
        common_http_protocol_options:
          idle_timeout: 2s # <--- NEW VALUE
        explicit_http_config:
          http_protocol_options:  
Finally, the sporadic 503 errors are over: oha test report http success

To Sum Up Here's an example of the values my team recommends to our clients: recap drawing Key Takeaways:
  1. The Load Balancer idle timeout should be less than the backend (upstream) idle/keepalive timeout.
  2. When we are working with long lived connections, the client (downstream) should use a keepalive smaller than the LB idle timeout.

Dirk Eddelbuettel: RcppArmadillo 15 CRAN Transition: Offering Office Hours

armadillo image Armadillo is a powerful and expressive C++ template library for linear algebra and scientific computing. It aims towards a good balance between speed and ease of use, has a syntax deliberately close to Matlab, and is useful for algorithm development directly in C++, or quick conversion of research code into production environments. RcppArmadillo integrates this library with the R environment and language and is widely used by (currently) 1273 other packages on CRAN, downloaded 41.8 million times (per the partial logs from the cloud mirrors of CRAN), and the CSDA paper (preprint / vignette) by Conrad and myself has been cited 651 times according to Google Scholar. Armadillo 15 brought changes. We mentioned these in the 15.0.2-1 and 15.0.2-1 release blog posts: (The second point is a consequence of the first. Prior to C++14, deprecation notes were issue via a macro, and the macro was set up by Conrad in the common way of allowing an override, which we took advantage of in RcppArmadillo effectively shielding downstream package. In C++14 this is now an attribute, and those cannot be suppressed.) We tested this then-upcoming change extensively: Thirteen reverse dependency runs expoloring different settings and leading to the current package setup where an automatic fallback to the last Armadillo 14 release offers fallback for hardwired C++11 use and Armadillo 15 others. Given the 1200+ reverse deoendencies, this took considerable time. All this was also quite extensively discussed with CRAN (especially Kurt Hornik) and documented / controlled via a series of issue tickets starting with overall issue #475 covering the subissues: The sixty pull requests (or emailed patches) followed a suggestion by CRAN to rank-order packages affected by their reverse dependencies sorted in descending package count. Now, while this change from Armadillo 14 to 15 was happening, CRAN also tightened the C++11 requirement for packages and imposed a deadline for changes. In discussion, CRAN also convinced me that a deadline for the deprecation warning, now unmasked, was viable (and is in fairness commensurate with similar, earlier changes triggered by changes in the behaviour of either gcc/g++ or clang/clang++). So we now have two larger deadline campaigns affecting the package (and as always there are some others). These deadlines are coming close: October 17 for the C++11 transition, and October 23 for the deprecation warning. Now, as became clear preparing the sixty pull requests and patches, these changes are often relatively straightforward. For the former, remove the C++11 enforcement and the package will likely build without changes. For the latter, make the often simple (e.g. swith from arma::is_finite to std::isfinite) change. I did not encounter anything much more complicated yet. The number of affected packages approximated by looking at all packages with a reverse dependency on RcppArmadillo and having a deadline can be computed as
suppressMessages(library(data.table))
D <- setDT(tools::CRAN_package_db())
P <- data.table(Package=tools::package_dependencies("RcppArmadillo", reverse=TRUE, db=D)[[1]])
W <- merge(P, D, all.x=TRUE)[is.na(Deadline)==FALSE,c(1:2,38,68)]
W

W[, nrevdep := length(tools::package_dependencies(Package, reverse=TRUE, recursive=TRUE, db=D)[[1]]), by=Package]
W[order(-nrevdep)]
and has been declining steadily from over 350 to now under 200. For that a big and heartfelt Thank You! to all the maintainers who already addressed their package and uploaded updated packages to CRAN. That rocks, and is truly appreciated. Yet the number is still large. And while issues #489 and #491 show a number of pending packages that have merged but not uploaded (yet?) there are also all the other packages I have not been able to look at in detail. While preparing sixty PRs / patches was viable over a period of a good week, I cannot create these for all packages. So with that said, here is a different suggestion for help: All of next week, I will be holding open door open source office hours online two times each day (11:00h to 13:00h Central, 16:00h to 18:00h Central) which can be booked via this booking link for Monday to Friday next week in either fifteen or thirty minutes slots you can book. This should offer Google Meet video conferencing (with jitsi as an alternate, you should be able to control that) which should allow for screen sharing. (I cannot hookup Zoom as my default account has organization settings with a different calendar integration.) If you are reading this and have a package that still needs helps, I hope to see you in the Open Source Office Hours to aid in the RcppArmadillo package updates for your package. Please book a slot!

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can sponsor me at GitHub.

23 September 2025

Ravi Dwivedi: Singapore Trip

In December 2024, I went on a trip through four countries - Singapore, Malaysia, Brunei, and Vietnam - with my friend Badri. This post covers our experiences in Singapore. I took an IndiGo flight from Delhi to Singapore, with a layover in Chennai. At the Chennai airport, I was joined by Badri. We had an early morning flight from Chennai that would land in Singapore in the afternoon. Within 48 hours of our scheduled arrival in Singapore, we submitted an arrival card online. At immigration, we simply needed to scan our passports at the gates, which opened automatically to let us through, and then give our address to an official nearby. The process was quick and smooth, but it unfortunately meant that we didn t get our passports stamped by Singapore. Before I left the airport, I wanted to visit the nature-themed park with a fountain I saw in pictures online. It is called Jewel Changi, and it took quite some walking to get there. After reaching the park, we saw a fountain that could be seen from all the levels. We roamed around for a couple of hours, then proceeded to the airport metro station to get to our hotel.
Jewel Changi A shot of Jewel Changi. Photo by Ravi Dwivedi. Released under the CC-BY-SA 4.0.
There were four ATMs on the way to the metro station, but none of them provided us with any cash. This was the first country (outside India, of course!) where my card didn t work at ATMs. To use the metro, one can tap the EZ-Link card or bank cards at the AFC gates to get in. You cannot buy tickets using cash. Before boarding the metro, I used my credit card to get Badri an EZ-Link card from a vending machine. It was 10 Singapore dollars ( 630) - 5 for the card, and 5 for the balance. I had planned to use my Visa credit card to pay for my own fare. I was relieved to see that my card worked, and I passed through the AFC gates. We had booked our stay at a hostel named Campbell s Inn, which was the cheapest we could find in Singapore. It was 1500 per night for dorm beds. The hostel was located in Little India. While Little India has an eponymous metro station, the one closest to our hostel was Rochor. On the way to the hostel, we found out that our booking had been canceled. We had booked from the Hostelworld website, opting to pay the deposit in advance and to pay the balance amount in person upon reaching. However, Hostelworld still tried to charge Badri s card again before our arrival. When the unauthorized charge failed, they sent an automatic message saying we tried to charge and to contact them soon to avoid cancellation, which we couldn t do as we were in the plane. Despite this, we went to the hostel to check the status of our booking. The trip from the airport to Rochor required a couple of transfers. It was 2 Singapore dollars (approx. 130) and took approximately an hour. Upon reaching the hostel, we were informed that our booking had indeed been canceled, and were not given any reason for the cancelation. Furthermore, no beds were available at the hostel for us to book on the spot. We decided to roam around and look for accommodation at other hostels in the area. Soon, we found a hostel by the name of Snooze Inn, which had two beds available. It was 36 Singapore dollars per person (around 2300) for a dormitory bed. Snooze Inn advertised supporting RuPay cards and UPI. Some other places in that area did the same. We paid using my card. We checked in and slept for a couple of hours after taking a shower. By the time we woke up, it was dark. We met Praveen s friend Sabeel to get my FLX1 phone. We also went to Mustafa Center nearby to exchange Indian rupees for Singapore dollars. Mustafa Center also had a shopping center with shops selling electronic items and souvenirs, among other things. When we were dropping off Sabeel at a bus stop, we discovered that the bus stops in Singapore had a digital board mentioning the bus routes for the stop and the number of minutes each bus was going to take. In addition to an organized bus system, Singapore had good pedestrian infrastructure. There were traffic lights and zebra crossings for pedestrians to cross the roads. Unlike in Indian cities, rules were being followed. Cars would stop for pedestrians at unmanaged zebra crossings; pedestrians would in turn wait for their crossing signal to turn green before attempting to walk across. Therefore, walking in Singapore was easy. Traffic rules were taken so seriously in Singapore I (as a pedestrian) was afraid of unintentionally breaking them, which could get me in trouble, as breaking rules is dealt with heavy fines in the country. For example, crossing roads without using a marked crossing (while being within 50 meters of it) - also known as jaywalking - is an offence in Singapore. Moreover, the streets were litter-free, and cleanliness seemed like an obsession. After exploring Mustafa Center, we went to a nearby 7-Eleven to top up Badri s EZ-Link card. He gave 20 Singapore dollars for the recharge, which credited the card by 19.40 Singapore dollars (0.6 dollars being the recharge fee). When I was planning this trip, I discovered that the World Chess Championship match was being held in Singapore. I seized the opportunity and bought a ticket in advance. The next day - the 5th of December - I went to watch the 9th game between Gukesh Dommaraju of India and Ding Liren of China. The venue was a hotel on Sentosa Island, and the ticket was 70 Singapore dollars, which was around 4000 at the time. We checked out from our hostel in the morning, as we were planning to stay with Badri s aunt that night. We had breakfast at a place in Little India. Then we took a couple of buses, followed by a walk to Sentosa Island. Paying the fare for the buses was similar to the metro - I tapped my credit card in the bus, while Badri tapped his EZ-Link card. We also had to tap it while getting off. If you are tapping your credit card to use public transport in Singapore, keep in mind that the total amount of all the trips taken on a day is deducted at the end. This makes it hard to determine the cost of individual trips. For example, I could take a bus and get off after tapping my card, but I would have no way to determine how much this journey cost. When you tap in, the maximum fare amount gets deducted. When you tap out, the balance amount gets refunded (if it s a shorter journey than the maximum fare one). So, there is incentive for passengers not to get off without tapping out. Going by your card statement, it looks like all that happens virtually, and only one statement comes in at the end. Maybe this combining only happens for international cards. We got off the bus a kilometer away from Sentosa Island and walked the rest of the way. We went on the Sentosa Boardwalk, which is itself a tourist attraction. I was using Organic Maps to navigate to the hotel Resorts World Sentosa, but Organic Maps route led us through an amusement park. I tried asking the locals (people working in shops) for directions, but it was a Chinese-speaking region, and they didn t understand English. Fortunately, we managed to find a local who helped us with the directions.
Sentosa Boardwalk A shot of Sentosa Boardwalk. Photo by Ravi Dwivedi. Released under the CC-BY-SA 4.0.
Following the directions, we somehow ended up having to walk on a road which did not have pedestrian paths. Singapore is a country with strict laws, so we did not want to walk on that road. Avoiding that road led us to the Michael Hotel. There was a person standing at the entrance, and I asked him for directions to Resorts World Sentosa. The person told me that the bus (which was standing at the entrance) would drop me there! The bus was a free service for getting to Resorts World Sentosa. Here I parted ways with Badri, who went to his aunt s place. I got to the Resorts Sentosa and showed my ticket to get in. There were two zones inside - the first was a room with a glass wall separating the audience and the players. This was the room to watch the game physically, and resembled a zoo or an aquarium. :) The room was also a silent room, which means talking or making noise was prohibited. Audiences were only allowed to have mobile phones for the first 30 minutes of the game - since I arrived late, I could not bring my phone inside that room. The other zone was outside this room. It had a big TV on which the game was being broadcast along with commentary by David Howell and Jovanka Houska - the official FIDE commentators for the event. If you don t already know, FIDE is the authoritative international chess body. I spent most of the time outside that silent room, giving me an opportunity to socialize. A lot of people were from Singapore. I saw there were many Indians there as well. Moreover, I had a good time with Vasudevan, a journalist from Tamil Nadu who was covering the match. He also asked questions to Gukesh during the post-match conference. His questions were in Tamil to lift Gukesh s spirits, as Gukesh is a Tamil speaker. Tea and coffee were free for the audience. I also bought a T-shirt from their stall as a souvenir. After the game, I took a shuttle bus from Resorts World Sentosa to a metro station, then travelled to Pasir Ris by metro, where Badri was staying with his aunt. I thought of getting something to eat, but could not find any caf s or restaurants while I was walking from the Pasir Ris metro station to my destination, and was positively starving when I got there. Badri s aunt s place was an apartment in a gated community. On the gate was a security guard who asked me the address of the apartment. Upon entering, there were many buildings. To enter the building, you need to dial the number of the apartment you want to go to and speak to them. I had seen that in the TV show Seinfeld, where Jerry s friends used to dial Jerry to get into his building. I was afraid they might not have anything to eat because I told them I was planning to get something on the way. This was fortunately not the case, and I was relieved to not have to sleep with an empty stomach. Badri s uncle gave us an idea of how safe Singapore is. He said that even if you forget your laptop in a public space, you can go back the next day to find it right there in the same spot. I also learned that owning cars was discouraged in Singapore - the government imposes a high registration fee on them, while also making public transport easy to use and affordable. I also found out that 7-Eleven was not that popular among residents in Singapore, unlike in Malaysia or Thailand. The next day was our third and final day in Singapore. We had a bus in the evening to Johor Bahru in Malaysia. We got up early, had breakfast, and checked out from Badri s aunt s home. A store by the name of Cat Socrates was our first stop for the day, as Badri wanted to buy some stationery. The plan was to take the metro, followed by the bus. So we got to Pasir Ris metro station. Next to the metro station was a mall. In the mall, Badri found an ATM where our cards worked, and we got some Singapore dollars. It was noon when we reached the stationery shop mentioned above. We had to walk a kilometer from the place where the bus dropped us. It was a hot, sunny day in Singapore, so walking was not comfortable. We had to go through residential areas in Singapore. We saw some non-touristy parts of Singapore. After we were done with the stationery shop, we went to a hawker center to get lunch. Hawker centers are unique to Singapore. They have a lot of shops that sell local food at cheap prices. It is similar to a food court. However, unlike the food courts in malls, hawker centers are open-air and can get quite hot.
Jewel Changi This is the hawker center we went to. Photo by Ravi Dwivedi. Released under the CC-BY-SA 4.0.
To have something, you just need to buy it from one of the shops and find a table. After you are done, you need to put your tray in the tray-collecting spots. I had a kaya toast with chai, since there weren t many vegetarian options. I also bought a persimmon from a nearby fruit vendor. On the other hand, Badri sampled some local non-vegetarian dishes.
A sign saying, 'No table littering, by law.' Table littering at the hawker center was prohibited by law. Photo by Ravi Dwivedi. Released under the CC-BY-SA 4.0.
Next, we took a metro to Raffles Place, as we wanted to visit Merlion, the icon of Singapore. It is a statue having the head of a lion and the body of a fish. While getting through the AFC gates, my card was declined. Therefore, I had to buy an EZ-Link card, which I had been avoiding because the card itself costs 5 Singapore dollars. From the Raffles Place metro station, we walked to Merlion. The place also gave a nice view of Marina Bay Sands. It was filled with tourists clicking pictures, and we also did the same.
Merlion from behind Merlion from behind, giving a good view of Marina Bay Sands. Photo by Ravi Dwivedi. Released under the CC-BY-SA 4.0.
After this, we went to the bus stop to catch our bus to the border city of Johor Bahru, Malaysia. The bus was more than an hour late, and we worried that we had missed the bus. I asked an Indian woman at the stop who also planned to take the same bus, and she told us that the bus was late. Finally, our bus arrived, and we set off for Johor Bahru. Before I finish, let me give you an idea of my expenditure. Singapore is an expensive country, and I realized that expenses could go up pretty quickly. Overall, my stay in Singapore for 3 days and 2 nights was approx. 5500 rupees. That too, when we stayed one night at Badri s aunt s place (so we didn t have to pay for accomodation for one of the nights) and didn t have to pay for a couple of meals. This amount doesn t include the ticket for the chess game, but includes the costs of getting there. If you are in Singapore, it is likely you will pay a visit to Sentosa Island anyway. Stay tuned for our experiences in Malaysia! Credits: Thanks to Dione, Sahil, Badri and Contrapunctus for reviewing the draft. Thanks to Bhe for spotting a duplicate sentence.

22 September 2025

Evgeni Golov: Booting Vagrant boxes with UEFI on Fedora: Permission denied

If you're still using Vagrant (I am) and try to boot a box that uses UEFI (like boxen/debian-13), a simple vagrant init boxen/debian-13 and vagrant up will entertain you with a nice traceback:
% vagrant up
Bringing machine 'default' up with 'libvirt' provider...
==> default: Checking if box 'boxen/debian-13' version '2025.08.20.12' is up to date...
==> default: Creating image (snapshot of base box volume).
==> default: Creating domain with the following settings...
==> default:  -- Name:              tmp.JV8X48n30U_default
==> default:  -- Description:       Source: /tmp/tmp.JV8X48n30U/Vagrantfile
==> default:  -- Domain type:       kvm
==> default:  -- Cpus:              1
==> default:  -- Feature:           acpi
==> default:  -- Feature:           apic
==> default:  -- Feature:           pae
==> default:  -- Clock offset:      utc
==> default:  -- Memory:            2048M
==> default:  -- Loader:            /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/OVMF_CODE.fd
==> default:  -- Nvram:             /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/efivars.fd
==> default:  -- Base box:          boxen/debian-13
==> default:  -- Storage pool:      default
==> default:  -- Image(vda):        /home/evgeni/.local/share/libvirt/images/tmp.JV8X48n30U_default.img, virtio, 20G
==> default:  -- Disk driver opts:  cache='default'
==> default:  -- Graphics Type:     vnc
==> default:  -- Video Type:        cirrus
==> default:  -- Video VRAM:        16384
==> default:  -- Video 3D accel:    false
==> default:  -- Keymap:            en-us
==> default:  -- TPM Backend:       passthrough
==> default:  -- INPUT:             type=mouse, bus=ps2
==> default:  -- CHANNEL:             type=unix, mode=
==> default:  -- CHANNEL:             target_type=virtio, target_name=org.qemu.guest_agent.0
==> default: Creating shared folders metadata...
==> default: Starting domain.
==> default: Removing domain...
==> default: Deleting the machine folder
/usr/share/gems/gems/fog-libvirt-0.13.1/lib/fog/libvirt/requests/compute/vm_action.rb:7:in 'Libvirt::Domain#create': Call to virDomainCreate failed: internal error: process exited while connecting to monitor: 2025-09-22T10:07:55.081081Z qemu-system-x86_64: -blockdev  "driver":"file","filename":"/home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/OVMF_CODE.fd","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap" : Could not open '/home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/OVMF_CODE.fd': Permission denied (Libvirt::Error)
    from /usr/share/gems/gems/fog-libvirt-0.13.1/lib/fog/libvirt/requests/compute/vm_action.rb:7:in 'Fog::Libvirt::Compute::Shared#vm_action'
    from /usr/share/gems/gems/fog-libvirt-0.13.1/lib/fog/libvirt/models/compute/server.rb:81:in 'Fog::Libvirt::Compute::Server#start'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/start_domain.rb:546:in 'VagrantPlugins::ProviderLibvirt::Action::StartDomain#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/set_boot_order.rb:22:in 'VagrantPlugins::ProviderLibvirt::Action::SetBootOrder#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/share_folders.rb:22:in 'VagrantPlugins::ProviderLibvirt::Action::ShareFolders#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/prepare_nfs_settings.rb:21:in 'VagrantPlugins::ProviderLibvirt::Action::PrepareNFSSettings#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/synced_folders.rb:87:in 'Vagrant::Action::Builtin::SyncedFolders#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/delayed.rb:19:in 'Vagrant::Action::Builtin::Delayed#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/synced_folder_cleanup.rb:28:in 'Vagrant::Action::Builtin::SyncedFolderCleanup#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/plugins/synced_folders/nfs/action_cleanup.rb:25:in 'VagrantPlugins::SyncedFolderNFS::ActionCleanup#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/prepare_nfs_valid_ids.rb:14:in 'VagrantPlugins::ProviderLibvirt::Action::PrepareNFSValidIds#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:127:in 'block in Vagrant::Action::Warden#finalize_action'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builder.rb:180:in 'Vagrant::Action::Builder#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/runner.rb:101:in 'block in Vagrant::Action::Runner#run'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/util/busy.rb:19:in 'Vagrant::Util::Busy.busy'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/runner.rb:101:in 'Vagrant::Action::Runner#run'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/call.rb:53:in 'Vagrant::Action::Builtin::Call#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:127:in 'block in Vagrant::Action::Warden#finalize_action'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builder.rb:180:in 'Vagrant::Action::Builder#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/runner.rb:101:in 'block in Vagrant::Action::Runner#run'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/util/busy.rb:19:in 'Vagrant::Util::Busy.busy'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/runner.rb:101:in 'Vagrant::Action::Runner#run'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/call.rb:53:in 'Vagrant::Action::Builtin::Call#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/create_network_interfaces.rb:197:in 'VagrantPlugins::ProviderLibvirt::Action::CreateNetworkInterfaces#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/create_networks.rb:40:in 'VagrantPlugins::ProviderLibvirt::Action::CreateNetworks#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/create_domain.rb:452:in 'VagrantPlugins::ProviderLibvirt::Action::CreateDomain#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/resolve_disk_settings.rb:143:in 'VagrantPlugins::ProviderLibvirt::Action::ResolveDiskSettings#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/create_domain_volume.rb:97:in 'VagrantPlugins::ProviderLibvirt::Action::CreateDomainVolume#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/handle_box_image.rb:127:in 'VagrantPlugins::ProviderLibvirt::Action::HandleBoxImage#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/handle_box.rb:56:in 'Vagrant::Action::Builtin::HandleBox#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/handle_storage_pool.rb:63:in 'VagrantPlugins::ProviderLibvirt::Action::HandleStoragePool#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/set_name_of_domain.rb:34:in 'VagrantPlugins::ProviderLibvirt::Action::SetNameOfDomain#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/provision.rb:80:in 'Vagrant::Action::Builtin::Provision#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-libvirt-0.11.2/lib/vagrant-libvirt/action/cleanup_on_failure.rb:21:in 'VagrantPlugins::ProviderLibvirt::Action::CleanupOnFailure#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:127:in 'block in Vagrant::Action::Warden#finalize_action'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builder.rb:180:in 'Vagrant::Action::Builder#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/runner.rb:101:in 'block in Vagrant::Action::Runner#run'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/util/busy.rb:19:in 'Vagrant::Util::Busy.busy'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/runner.rb:101:in 'Vagrant::Action::Runner#run'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/call.rb:53:in 'Vagrant::Action::Builtin::Call#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/box_check_outdated.rb:93:in 'Vagrant::Action::Builtin::BoxCheckOutdated#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builtin/config_validate.rb:25:in 'Vagrant::Action::Builtin::ConfigValidate#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/warden.rb:48:in 'Vagrant::Action::Warden#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/builder.rb:180:in 'Vagrant::Action::Builder#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/runner.rb:101:in 'block in Vagrant::Action::Runner#run'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/util/busy.rb:19:in 'Vagrant::Util::Busy.busy'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/action/runner.rb:101:in 'Vagrant::Action::Runner#run'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/machine.rb:248:in 'Vagrant::Machine#action_raw'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/machine.rb:217:in 'block in Vagrant::Machine#action'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/environment.rb:631:in 'Vagrant::Environment#lock'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/machine.rb:203:in 'Method#call'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/machine.rb:203:in 'Vagrant::Machine#action'
    from /usr/share/vagrant/gems/gems/vagrant-2.3.4/lib/vagrant/batch_action.rb:86:in 'block (2 levels) in Vagrant::BatchAction#run'
The important part here is
Call to virDomainCreate failed: internal error: process exited while connecting to monitor:
2025-09-22T10:07:55.081081Z qemu-system-x86_64: -blockdev  "driver":"file","filename":"/home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/OVMF_CODE.fd","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap" :
Could not open '/home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/OVMF_CODE.fd': Permission denied (Libvirt::Error)
Of course we checked that the file permissions on this file are correct (I'll save you the ls output), so what's next? Yes, of course, SELinux!
# ausearch -m AVC
time->Mon Sep 22 12:07:55 2025
type=AVC msg=audit(1758535675.080:1613): avc:  denied    read   for  pid=257204 comm="qemu-system-x86" name="OVMF_CODE.fd" dev="dm-2" ino=1883946 scontext=unconfined_u:unconfined_r:svirt_t:s0:c352,c717 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=0
A process in the svirt_t domain tries to access something in the user_home_t domain and is denied by the kernel. So far, SELinux is both working as designed and preventing us from doing our work, nice. For "normal" (non-UEFI) boxes, Vagrant uploads the image to libvirt, which stores it in ~/.local/share/libvirt/images/ and boots fine from there. For UEFI boxen, one also needs loader and nvram files, which Vagrant keeps in ~/.vagrant.d/boxes/<box_name> and that's what explodes in our face here. As ~/.local/share/libvirt/images/ works well, and is labeled svirt_home_t let's see what other folders use that label:
# semanage fcontext -l  grep svirt_home_t
/home/[^/]+/\.cache/libvirt/qemu(/.*)?             all files          unconfined_u:object_r:svirt_home_t:s0
/home/[^/]+/\.config/libvirt/qemu(/.*)?            all files          unconfined_u:object_r:svirt_home_t:s0
/home/[^/]+/\.libvirt/qemu(/.*)?                   all files          unconfined_u:object_r:svirt_home_t:s0
/home/[^/]+/\.local/share/gnome-boxes/images(/.*)? all files          unconfined_u:object_r:svirt_home_t:s0
/home/[^/]+/\.local/share/libvirt/boot(/.*)?       all files          unconfined_u:object_r:svirt_home_t:s0
/home/[^/]+/\.local/share/libvirt/images(/.*)?     all files          unconfined_u:object_r:svirt_home_t:s0
Okay, that all makes sense, and it's just missing the Vagrant-specific folders!
# semanage fcontext -a -t svirt_home_t '/home/[^/]+/\.vagrant.d/boxes(/.*)?'
Now relabel the Vagrant boxes:
% restorecon -rv ~/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13 from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/metadata_url from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12 from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/box_0.img from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/metadata.json from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/Vagrantfile from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/OVMF_CODE.fd from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/OVMF_VARS.fd from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/box_update_check from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
Relabeled /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/efivars.fd from unconfined_u:object_r:user_home_t:s0 to unconfined_u:object_r:svirt_home_t:s0
And it works!
% vagrant up
Bringing machine 'default' up with 'libvirt' provider...
==> default: Checking if box 'boxen/debian-13' version '2025.08.20.12' is up to date...
==> default: Creating image (snapshot of base box volume).
==> default: Creating domain with the following settings...
==> default:  -- Name:              tmp.JV8X48n30U_default
==> default:  -- Description:       Source: /tmp/tmp.JV8X48n30U/Vagrantfile
==> default:  -- Domain type:       kvm
==> default:  -- Cpus:              1
==> default:  -- Feature:           acpi
==> default:  -- Feature:           apic
==> default:  -- Feature:           pae
==> default:  -- Clock offset:      utc
==> default:  -- Memory:            2048M
==> default:  -- Loader:            /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/OVMF_CODE.fd
==> default:  -- Nvram:             /home/evgeni/.vagrant.d/boxes/boxen-VAGRANTSLASH-debian-13/2025.08.20.12/libvirt/efivars.fd
==> default:  -- Base box:          boxen/debian-13
==> default:  -- Storage pool:      default
==> default:  -- Image(vda):        /home/evgeni/.local/share/libvirt/images/tmp.JV8X48n30U_default.img, virtio, 20G
==> default:  -- Disk driver opts:  cache='default'
==> default:  -- Graphics Type:     vnc
==> default:  -- Video Type:        cirrus
==> default:  -- Video VRAM:        16384
==> default:  -- Video 3D accel:    false
==> default:  -- Keymap:            en-us
==> default:  -- TPM Backend:       passthrough
==> default:  -- INPUT:             type=mouse, bus=ps2
==> default:  -- CHANNEL:             type=unix, mode=
==> default:  -- CHANNEL:             target_type=virtio, target_name=org.qemu.guest_agent.0
==> default: Creating shared folders metadata...
==> default: Starting domain.
==> default: Domain launching with graphics connection settings...
==> default:  -- Graphics Port:      5900
==> default:  -- Graphics IP:        127.0.0.1
==> default:  -- Graphics Password:  Not defined
==> default:  -- Graphics Websocket: 5700
==> default: Waiting for domain to get an IP address...
==> default: Waiting for machine to boot. This may take a few minutes...
    default: SSH address: 192.168.124.157:22
    default: SSH username: vagrant
    default: SSH auth method: private key
    default:
    default: Vagrant insecure key detected. Vagrant will automatically replace
    default: this with a newly generated keypair for better security.
    default:
    default: Inserting generated public key within guest...
    default: Removing insecure key from the guest if it's present...
    default: Key inserted! Disconnecting and reconnecting using new SSH key...
==> default: Machine booted and ready!

Vincent Bernat: Akvorado release 2.0

Akvorado 2.0 was released today! Akvorado collects network flows with IPFIX and sFlow. It enriches flows and stores them in a ClickHouse database. Users can browse the data through a web console. This release introduces an important architectural change and other smaller improvements. Let s dive in!
$ git diff --shortstat v1.11.5
 493 files changed, 25015 insertions(+), 21135 deletions(-)

New outlet service The major change in Akvorado 2.0 is splitting the inlet service into two parts: the inlet and the outlet. Previously, the inlet handled all flow processing: receiving, decoding, and enrichment. Flows were then sent to Kafka for storage in ClickHouse:
Akvorado flow processing before the change: flows are received and processed by the inlet, sent to Kafka and stored in ClickHouse
Akvorado flow processing before the introduction of the outlet service
Network flows reach the inlet service using UDP, an unreliable protocol. The inlet must process them fast enough to avoid losing packets. To handle a high number of flows, the inlet spawns several sets of workers to receive flows, fetch metadata, and assemble enriched flows for Kafka. Many configuration options existed for scaling, which increased complexity for users. The code needed to avoid blocking at any cost, making the processing pipeline complex and sometimes unreliable, particularly the BMP receiver.1 Adding new features became difficult without making the problem worse.2 In Akvorado 2.0, the inlet receives flows and pushes them to Kafka without decoding them. The new outlet service handles the remaining tasks:
Akvorado flow processing after the change: flows are received by the inlet, sent to Kafka, processed by the outlet and inserted in ClickHouse
Akvorado flow processing after the introduction of the outlet service
This change goes beyond a simple split:3 the outlet now reads flows from Kafka and pushes them to ClickHouse, two tasks that Akvorado did not handle before. Flows are heavily batched to increase efficiency and reduce the load on ClickHouse using ch-go, a low-level Go client for ClickHouse. When batches are too small, asynchronous inserts are used (e20645). The number of outlet workers scales dynamically (e5a625) based on the target batch size and latency (50,000 flows and 5 seconds by default). This new architecture also allows us to simplify and optimize the code. The outlet fetches metadata synchronously (e20645). The BMP component becomes simpler by removing cooperative multitasking (3b9486). Reusing the same RawFlow object to decode protobuf-encoded flows from Kafka reduces pressure on the garbage collector (8b580f). The effect on Akvorado s overall performance was somewhat uncertain, but a user reported 35% lower CPU usage after migrating from the previous version, plus resolution of the long-standing BMP component issue.

Other changes This new version includes many miscellaneous changes, such as completion for source and destination ports (f92d2e), and automatic restart of the orchestrator service (0f72ff) when configuration changes to avoid a common pitfall for newcomers. Let s focus on some key areas for this release: observability, documentation, CI, Docker, Go, and JavaScript.

Observability Akvorado exposes metrics to provide visibility into the processing pipeline and help troubleshoot issues. These are available through Prometheus HTTP metrics endpoints, such as /api/v0/inlet/metrics. With the introduction of the outlet, many metrics moved. Some were also renamed (4c0b15) to match Prometheus best practices. Kafka consumer lag was added as a new metric (e3a778). If you do not have your own observability stack, the Docker Compose setup shipped with Akvorado provides one. You can enable it by activating the profiles introduced for this purpose (529a8f). The prometheus profile ships Prometheus to store metrics and Alloy to collect them (2b3c46, f81299, and 8eb7cd). Redis and Kafka metrics are collected through the exporter bundled with Alloy (560113). Other metrics are exposed using Prometheus metrics endpoints and are automatically fetched by Alloy with the help of some Docker labels, similar to what is done to configure Traefik. cAdvisor was also added (83d855) to provide some container-related metrics. The loki profile ships Loki to store logs (45c684). While Alloy can collect and ship logs to Loki, its parsing abilities are limited: I could not find a way to preserve all metadata associated with structured logs produced by many applications, including Akvorado. Vector replaces Alloy (95e201) and features a domain-specific language, VRL, to transform logs. Annoyingly, Vector currently cannot retrieve Docker logs from before it was started. Finally, the grafana profile ships Grafana, but the shipped dashboards are broken. This is planned for a future version.

Documentation The Docker Compose setup provided by Akvorado makes it easy to get the web interface up and running quickly. However, Akvorado requires a few mandatory steps to be functional. It ships with comprehensive documentation, including a chapter about troubleshooting problems. I hoped this documentation would reduce the support burden. It is difficult to know if it works. Happy users rarely report their success, while some users open discussions asking for help without reading much of the documentation. In this release, the documentation was significantly improved.
$ git diff --shortstat v1.11.5 -- console/data/docs
 10 files changed, 1873 insertions(+), 1203 deletions(-)
The documentation was updated (fc1028) to match Akvorado s new architecture. The troubleshooting section was rewritten (17a272). Instructions on how to improve ClickHouse performance when upgrading from versions earlier than 1.10.0 was added (5f1e9a). An LLM proofread the entire content (06e3f3). Developer-focused documentation was also improved (548bbb, e41bae, and 871fc5). From a usability perspective, table of content sections are now collapsable (c142e5). Admonitions help draw user attention to important points (8ac894).
Admonition in Akvorado documentation to ask a user not to open an issue or start a discussion before reading the documentation
Example of use of admonitions in Akvorado's documentation

Continuous integration This release includes efforts to speed up continuous integration on GitHub. Coverage and race tests run in parallel (6af216 and fa9e48). The Docker image builds during the tests but gets tagged only after they succeed (8b0dce).
GitHub workflow for CI with many jobs, some of them running in parallel, some not
GitHub workflow to test and build Akvorado
End-to-end tests (883e19) ensure the shipped Docker Compose setup works as expected. Hurl runs tests on various HTTP endpoints, particularly to verify metrics (42679b and 169fa9). For example:
## Test inlet has received NetFlow flows
GET http://127.0.0.1:8080/prometheus/api/v1/query
[Query]
query: sum(akvorado_inlet_flow_input_udp_packets_total job="akvorado-inlet",listener=":2055" )
HTTP 200
[Captures]
inlet_receivedflows: jsonpath "$.data.result[0].value[1]" toInt
[Asserts]
variable "inlet_receivedflows" > 10
## Test inlet has sent them to Kafka
GET http://127.0.0.1:8080/prometheus/api/v1/query
[Query]
query: sum(akvorado_inlet_kafka_sent_messages_total job="akvorado-inlet" )
HTTP 200
[Captures]
inlet_sentflows: jsonpath "$.data.result[0].value[1]" toInt
[Asserts]
variable "inlet_sentflows" >=   inlet_receivedflows  

Docker Akvorado ships with a comprehensive Docker Compose setup to help users get started quickly. It ensures a consistent deployment, eliminating many configuration-related issues. It also serves as a living documentation of the complete architecture. This release brings some small enhancements around Docker: Previously, many Docker images were pulled from the Bitnami Containers library. However, VMWare acquired Bitnami in 2019 and Broadcom acquired VMWare in 2023. As a result, Bitnami images were deprecated in less than a month. This was not really a surprise4. Previous versions of Akvorado had already started moving away from them. In this release, the Apache project s Kafka image replaces the Bitnami one (1eb382). Thanks to the switch to KRaft mode, Zookeeper is no longer needed (0a2ea1, 8a49ca, and f65d20). Akvorado s Docker images were previously compiled with Nix. However, building AArch64 images on x86-64 is slow because it relies on QEMU userland emulation. The updated Dockerfile uses multi-stage and multi-platform builds: one stage builds the JavaScript part on the host platform, one stage builds the Go part cross-compiled on the host platform, and the final stage assembles the image on top of a slim distroless image (268e95 and d526ca).
# This is a simplified version
FROM --platform=$BUILDPLATFORM node:20-alpine AS build-js
RUN apk add --no-cache make
WORKDIR /build
COPY console/frontend console/frontend
COPY Makefile .
RUN make console/data/frontend
FROM --platform=$BUILDPLATFORM golang:alpine AS build-go
RUN apk add --no-cache make curl zip
WORKDIR /build
COPY . .
COPY --from=build-js /build/console/data/frontend console/data/frontend
RUN go mod download
RUN make all-indep
ARG TARGETOS TARGETARCH TARGETVARIANT VERSION
RUN make
FROM gcr.io/distroless/static:latest
COPY --from=build-go /build/bin/akvorado /usr/local/bin/akvorado
ENTRYPOINT [ "/usr/local/bin/akvorado" ]
When building for multiple platforms with --platform linux/amd64,linux/arm64,linux/arm/v7, the build steps until the highlighted line execute only once for all platforms. This significantly speeds up the build. Akvorado now ships Docker images for these platforms: linux/amd64, linux/amd64/v3, linux/arm64, and linux/arm/v7. When requesting ghcr.io/akvorado/akvorado, Docker selects the best image for the current CPU. On x86-64, there are two choices. If your CPU is recent enough, Docker downloads linux/amd64/v3. This version contains additional optimizations and should run faster than the linux/amd64 version. It would be interesting to ship an image for linux/arm64/v8.2, but Docker does not support the same mechanism for AArch64 yet (792808).

Go This release includes many changes related to Go but not visible to the users.

Toolchain In the past, Akvorado supported the two latest Go versions, preventing immediate use of the latest enhancements. The goal was to allow users of stable distributions to use Go versions shipped with their distribution to compile Akvorado. However, this became frustrating when interesting features, like go tool, were released. Akvorado 2.0 requires Go 1.25 (77306d) but can be compiled with older toolchains by automatically downloading a newer one (94fb1c).5 Users can still override GOTOOLCHAIN to revert this decision. The recommended toolchain updates weekly through CI to ensure we get the latest minor release (5b11ec). This change also simplifies updates to newer versions: only go.mod needs updating. Thanks to this change, Akvorado now uses wg.Go() (77306d) and I have started converting some unit tests to the new test/synctest package (bd787e, 7016d8, and 159085).

Testing When testing equality, I use a helper function Diff() to display the differences when it fails:
got := input.Keys()
expected := []int 1, 2, 3 
if diff := helpers.Diff(got, expected); diff != ""  
    t.Fatalf("Keys() (-got, +want):\n%s", diff)
 
This function uses kylelemons/godebug. This package is no longer maintained and has some shortcomings: for example, by default, it does not compare struct private fields, which may cause unexpectedly successful tests. I replaced it with google/go-cmp, which is stricter and has better output (e2f1df).

Another package for Kafka Another change is the switch from Sarama to franz-go to interact with Kafka (756e4a and 2d26c5). The main motivation for this change is to get a better concurrency model. Sarama heavily relies on channels and it is difficult to understand the lifecycle of an object handed to this package. franz-go uses a more modern approach with callbacks6 that is both more performant and easier to understand. It also ships with a package to spawn fake Kafka broker clusters, which is more convenient than the mocking functions provided by Sarama.

Improved routing table for BMP To store its routing table, the BMP component used kentik/patricia, an implementation of a patricia tree focused on reducing garbage collection pressure. gaissmai/bart is a more recent alternative using an adaptation of [Donald Knuth s ART algorithm][] that promises better performance and delivers it: 90% faster lookups and 27% faster insertions (92ee2e and fdb65c). Unlike kentik/patricia, gaissmai/bart does not help efficiently store values attached to each prefix. I adapted the same approach as kentik/patricia to store route lists for each prefix: store a 32-bit index for each prefix, and use it to build a 64-bit index for looking up routes in a map. This leverages Go s efficient map structure. gaissmai/bart also supports a lockless routing table version, but this is not simple because we would need to extend this to the map storing the routes and to the interning mechanism. I also attempted to use Go s new unique package to replace the intern package included in Akvorado, but performance was worse.7

Miscellaneous Previous versions of Akvorado were using a custom Protobuf encoder for performance and flexibility. With the introduction of the outlet service, Akvorado only needs a simple static schema, so this code was removed. However, it is possible to enhance performance with planetscale/vtprotobuf (e49a74, and 8b580f). Moreover, the dependency on protoc, a C++ program, was somewhat annoying. Therefore, Akvorado now uses buf, written in Go, to convert a Protobuf schema into Go code (f4c879). Another small optimization to reduce the size of the Akvorado binary by 10 MB was to compress the static assets embedded in Akvorado in a ZIP file. It includes the ASN database, as well as the SVG images for the documentation. A small layer of code makes this change transparent (b1d638 and e69b91).

JavaScript Recently, two large supply-chain attacks hit the JavaScript ecosystem: one affecting the popular packages chalk and debug and another impacting the popular package @ctrl/tinycolor. These attacks also exist in other ecosystems, but JavaScript is a prime target due to heavy use of small third-party dependencies. The previous version of Akvorado relied on 653 dependencies. npm-run-all was removed (3424e8, 132 dependencies). patch-package was removed (625805 and e85ff0, 69 dependencies) by moving missing TypeScript definitions to env.d.ts. eslint was replaced with oxlint, a linter written in Rust (97fd8c, 125 dependencies, including the plugins). I switched from npm to Pnpm, an alternative package manager (fce383). Pnpm does not run install scripts by default8 and prevents installing packages that are too recent. It is also significantly faster.9 Node.js does not ship Pnpm but it ships Corepack, which allows us to use Pnpm without installing it. Pnpm can also list licenses used by each dependency, removing the need for license-compliance (a35ca8, 42 dependencies). For additional speed improvements, beyond switching to Pnpm and Oxlint, Vite was replaced with its faster Rolldown version (463827). After these changes, Akvorado only pulls 225 dependencies.

Next steps I would like to land three features in the next version of Akvorado:
  • Add Grafana dashboards to complete the observability stack. See issue #1906 for details.
  • Integrate OVH s Grafana plugin by providing a stable API for such integrations. Akvorado s web console would still be useful for browsing results, but if you want to build and share dashboards, you should switch to Grafana. See issue #1895.
  • Move some work currently done in ClickHouse (custom dictionaries, GeoIP and IP enrichment) back into the outlet service. This should give more flexibility for adding features like the one requested in issue #1030. See issue #2006.

I started working on splitting the inlet into two parts more than one year ago. I found more motivation in recent months, partly thanks to Claude Code, which I used as a rubber duck. Almost none of the produced code was kept:10 it is like an intern who does not learn.

  1. Many attempts were made to make the BMP component both performant and not blocking. See for example PR #254, PR #255, and PR #278. Despite these efforts, this component remained problematic for most users. See issue #1461 as an example.
  2. Some features have been pushed to ClickHouse to avoid the processing cost in the inlet. See for example PR #1059.
  3. This is the biggest commit:
    $ git show --shortstat ac68c5970e2c   tail -1
    231 files changed, 6474 insertions(+), 3877 deletions(-)
    
  4. Broadcom is known for its user-hostile moves. Look at what happened with VMWare.
  5. As a Debian developer, I dislike these mechanisms that circumvent the distribution package manager. The final straw came when Go 1.25 spent one month in the Debian NEW queue, an arbitrary mechanism I don t like at all.
  6. In the early years of Go, channels were heavily promoted. Sarama was designed during this period. A few years later, a more nuanced approach emerged. See notably Go channels are bad and you should feel bad.
  7. This should be investigated further, but my theory is that the intern package uses 32-bit integers, while unique uses 64-bit pointers. See commit 74e5ac.
  8. This is also possible with npm. See commit dab2f7.
  9. An even faster alternative is Bun, but it is less available.
  10. The exceptions are part of the code for the admonition blocks, the code for collapsing the table of content, and part of the documentation.

18 September 2025

John Goerzen: Running an Accurate 80 25 DOS-Style Console on Modern Linux Is Possible After All

Here, in classic Goerzen deep dive fashion, is more information than you knew you wanted about a topic you ve probably never thought of. I found it pretty interesting, because it took me down a rabbit hole of subsystems I ve never worked with much and a mishmash of 1980s and 2020s tech. I had previously tried and failed to get an actual 80x25 Linux console, but I ve since figured it out! This post is about the Linux text console not X or Wayland. We re going to get the console right without using those systems. These instructions are for Debian trixie, but should be broadly applicable elsewhere also. The end result can look like this: Photo of a color VGA monitor displaying a BBS login screen (That s a Wifi Retromodem that I got at VCFMW last year in the Hayes modem case)

What s a pixel? How would you define a pixel these days? Probably something like a uniquely-addressable square dot in a two-dimensional grid . In the world of VGA and CRTs, that was just a logical abstraction. We got an API centered around that because it was convenient. But, down the VGA cable and on the device, that s not what a pixel was. A pixel, back then, was a time interval. On a multisync monitor, which were common except in the very early days of VGA, the timings could be adjusted which produced logical pixels of different sizes. Those screens often had a maximum resolution but not necessarily a native resolution in the sense that an LCD panel does. Different timings produced different-sized pixels with equal clarity (or, on cheaper monitors, equal fuzziness). A side effect of this was that pixels need not be square. And, in fact, in the standard DOS VGA 80x25 text mode, they weren t. You might be seeing why DVI, DisplayPort, and HDMI replaced VGA for LCD monitors: with a VGA cable, you did a pixel-to-analog-timings conversion, then the display did a timings-to-pixels conversion, and this process could be a bit lossy. (Hence why you sometimes needed to fill the screen with an image and push the center button on those older LCD screens) (Note to the pedantically-inclined: yes I am aware that I have simplified several things here; for instance, a color LCD pixel is made up of approximately 3 sub-dots of varying colors, and that things like color eInk displays have two pixel grids with different sizes of pixels layered atop each other, and printers are another confusing thing altogether, and and and . MOST PEOPLE THINK OF A PIXEL AS A DOT THESE DAYS, OK?)

What was DOS text mode? We think of this as the standard display: 80 columns wide and 25 rows tall. 80x25. By the time Linux came along, the standard Linux console was VGA text mode something like the 4th incarnation of text modes on PCs (after CGA, MDA, and EGA). VGA also supported certain other sizes of characters giving certain other text dimensions, but if I cover all of those, this will explode into a ridiculously more massive page than it already is. So to display text on an 80x25 DOS VGA system, ultimately characters and attributes were written into the text buffer in memory. The VGA system then rendered it to the display as a 720x400 image (at 70Hz) with non-square pixels such that the result was approximately a 4:3 aspect ratio. The font used for this rendering was a bitmapped one using 8x16 cells. You might do some math here and point out that 8 * 80 is only 640, and you d be correct. The fonts were 8x16 but the rendered cells were 9x16. The extra pixel was normally used for spacing between characters. However, in line graphics mode, characters 0xC0 through 0xDF repeated the 8th column in the position of the 9th, allowing the continuous line-drawing characters we re used to from TUIs.

Problems rendering DOS fonts on modern systems By now, you re probably seeing some of the issues we have rendering DOS screens on more modern systems. These aren t new at all; I remember some of these from back in the days when I ran OS/2, and I think also saw them on various terminals and consoles in OS/2 and Windows. Some issues you d encounter would be:
  • Incorrect aspect ratio caused by using the original font and rendering it using 1:1 square pixels (resulting in a squashed appearance)
  • Incorrect aspect ratio for ANOTHER reason, caused by failing to render column 9, resulting in text that is overall too narrow
  • Characters appearing to be touching each other when they shouldn t (failing to render column 9; looking at you, dosbox)
  • Gaps between line drawing characters that should be continuous, caused by rendering column 9 as empty space in all cases

Character set issues DOS was around long before Unicode was. In the DOS world, there were codepages that selected the glyphs for roughly the high half of the 256 possible characters. CP437 was the standard for the USA; others existed for other locations that needed different characters. On Unix, the USA pre-Unicode standard was Latin-1. Same concept, but with different character mappings. Nowadays, just about everything is based on UTF-8. So, we need some way to map our CP437 glyphs into Unicode space. If we are displaying DOS-based content, we ll also need a way to map CP437 characters to Unicode for display later, and we need these maps to match so that everything comes out right. Whew. So, let s get on with setting this up!

Selecting the proper video mode As explained in my previous post, proper hardware support for DOS text mode is limited to x86 machines that do not use UEFI. Non-x86 machines, or x86 machines with UEFI, simply do not contain the necessary support for it. As these are now standard, most of the time, the text console you see on Linux is actually the kernel driving the video hardware in graphics mode, and doing the text rendering in software. That s all well and good, but it makes it quite difficult to actually get an 80x25 console. First, we need to be running at 720x400. This is where I ran into difficulty last time. I realized that my laptop s LCD didn t advertise any video modes other than its own native resolution. However, almost all external monitors will, and 720x400@70 is a standard VGA mode from way back, so it should be well-supported. You need to find the Linux device name for your device. You can look at the possible devices with ls -l /sys/class/drm. If you also have a GUI, xrandr may help too. But in any case, each directory under /sys/class/drm has a file named modes, and if you cat them all, you will eventually come across one with a bunch of modes defined. Drop the leading card0 or whatever from the directory name, and that s your device. (Verify that 720x400 is in modes while you re at it.) Now, you re going to edit /etc/default/grub and add something like this to GRUB_CMDLINE_LINUX_DEFAULT:
video=DP-1:720x400@70
Of course, replace DP-1 with whatever your device is. Now you can run update-grub and reboot. You should have a 720x400 display. At first, I thought I had succeeded by using Linux s built-in VGA font with that mode. But it looked too tall. After noticing that repeated 0s were touching, I got suspicious about the missing 9th column in the cells. stty -a showed that my screen was 90x25, which is exactly what it would show if I was using 8x16 instead of 9x16 cells. Sooo . I need to prepare a 9x16 font.

Preparing a font Here s where it gets complicated. I ll give you the simple version and the hard mode. The simple mode is this: Download https://www.complete.org/downloads/CP437-VGA.psf.gz and stick it in /usr/local/etc, then skip to the Activating the font section below. The font assembled here is based on the Ultimate Oldschool PC Font Pack v2.2, which is (c) 2016-2020 VileR and licensed under Creative Commons Attribution-ShareAlike 4.0 International License. My psf file is derived from this using the instructions below.

Building it yourself First, install some necessary software: apt-get install fontforge bdf2psf Start by going to the Oldschool PC Font Pack Download page. Download oldschool_pc_font_pack_v2.2_FULL.zip and unpack it. The file we re interested in is otb - Bm (linux bitmap)/Bm437_IBM_VGA_9x16.otb. Open it in fontforge by running fontforge BmPlus_IBM_VGA_9x16.otb. When it asks if you will load the bitmap fonts, hit select all, then yes. Go to File -> generate fonts. Save in a BDF, no need for outlines, and use guess for resolution. Now you have a file such as Bm437_IBM_VGA_9x16-16.bdf. Excellent. Now we need to generate a Unicode map file. We will make sure this matches the system s by enumerating every character from 0x00 to 0xFF, converting it from CP437 to Unicode, and writing the appropriate map. Here s a Python script to do that:
for i in range(0, 256):
    cp437b = b'%c' % i
    uni = ord(cp437b.decode('cp437'))
    print(f"U+ uni:04x ")
Save that file as genmap.py and run python3 genmap.py > cp437-uni. Now, we re ready to build the psf file:
bdf2psf --fb Bm437_IBM_VGA_9x16-16.bdf \
  /dev/null cp437-uni 256 CP437-VGA.psf
By convention, we normally store these files gzipped, so gzip CP437-VGA.psf. You can test it on the console with setfont CP437-VGA.psf.gz. Now copy this file into /usr/local/etc.

Activating the font Now, edit /etc/default/console-setup. It should look like this:
# CONFIGURATION FILE FOR SETUPCON

# Consult the console-setup(5) manual page.

ACTIVE_CONSOLES="/dev/tty[1-6]"

CHARMAP="UTF-8"

CODESET="Lat15"
FONTFACE="VGA"
FONTSIZE="8x16"
FONT=/usr/local/etc/CP437-VGA.psf.gz

VIDEOMODE=

# The following is an example how to use a braille font
# FONT='lat9w-08.psf.gz brl-8x8.psf'
At this point, you should be able to reboot. You should have a proper 80x25 display! Log in and run stty -a to verify it is indeed 80x25.

Using and testing CP437 Part of the point of CP437 is to be able to access BBSs, ANSI art, and similar. Now, remember, the Linux console is still in UTF-8 mode, so we have to translate CP437 to UTF-8, then let our font map translate it back to CP437. A weird trip, but it works. Let s test it using the Textfiles ANSI art collection. In the artworks section, I randomly grabbed a file near the top: borgman.ans. Download that, and display with:
clear; iconv -f CP437 -t UTF-8 < borgman.ans
You should see something similar to but actually more accurate than the textfiles PNG rendering of it, which you ll note has an incorrect aspect ratio and some rendering issues. I spot-checked with a few others and they seemed to look good. belinda.ans in particular tries quite a few characters and should give you a good sense if it is working.

Use with interactive programs That s all well and good, but you re probably going to want to actually use this with some interactive program that expects CP437. Maybe Minicom, Kermit, or even just telnet? For this, you ll want to apt-get install luit. luit maps CP437 (or any other encoding) to UTF-8 for display, and then of course the Linux console maps UTF-8 back to the CP437 font. Here s a way you can repeat the earlier experiment using luit to run the cat program:
clear; luit -encoding CP437 cat borgman.ans
You can run any command under luit. You can even run luit -encoding CP437 bash if you like. If you do this, it is probably a good idea to follow my instructions on generating locales on my post on serial terminals, and then within luit, set LANG=en_us.IBM437. But note especially that you can run programs like minicom and others for accessing BBSs under luit.

Final words This gave you a nice DOS-type console. Although it doesn t have glyphs for many codepoints, it does run in UTF-8 mode and therefore is compatible with modern software. You can achieve greater compatibility with more UTF-8 codepoints with the DOS font, at the expense of accuracy of character rendering (especially for the double-line drawing characters) by using /usr/share/bdf2psf/standard.equivalents instead of /dev/null in the bdf2psf command. Or you could go for another challenge, such as using the DEC vt-series fonts for coverage of ISO-8859-1. But just using fonts extracted from DEC ROM won t work properly, because DEC terminals had even more strangeness going on than DOS fonts.

11 September 2025

Christoph Berg: A Trip To Vienna With Surprises

My trip to pgday.at started Wednesday at the airport in D sseldorf. I was there on time, and the plane started with an estimated flight time of about 90 minutes. About half an hour into the flight, the captain announced that we would be landing in 30 minutes - in D sseldorf, because of some unspecified technical problems. Three hours after the original departure time, the plane made another attempt, and we made it to Vienna.
On the plane I had already met Dirk Krautschick who had the great honor of bringing Slonik (in the form of a big extra bag) to the conference, and we took a taxi to the hotel. On the taxi, the next surprise happened: Hans-J rgen Sch nig unfortunately couldn't make it to the conference, and his talks had to be replaced. I had submitted a talk to the conference, but it was not accepted, and neither queued on the reserve list. But two speakers on the reserve list had cancelled, and another was already giving a talk in parallel to the slot that had to be filled, so Pavlo messaged me if I could hold the talk - well of course I could. Before, I didn't have any specific plans for the evening yet, but suddenly I was a speaker, so I joined the folks going to the speakers dinner at the Wiener Grill Haus two corners from the hotel. It was a very nice evening, chatting with a lot of folks from the PostgreSQL community that I had not seen for a while. Thursday was the conference day. The hotel was a short walk from the venue, the Apothekertrakt in Vienna's Schloss Sch nbrunn. The courtyard was already filled with visitors registering for the conference. Since I originally didn't have a talk scheduled, I had signed up to volunteer for a shift as room host. We got our badge and swag bag, and I changed into the "crew" T-shirt. The opening and sponsor keynotes took place in the main room, the Orangerie. We were over 100 people in the room, but apparently still not enough to really fill it, so the acoustics with some echo made it a bit difficult to understand everything. I hope that part can be improved for next time (which is planned to happen!). I was host for the Maximilian room, where the sponsor sessions were scheduled in the morning. The first talk was by our Peter Hofer, also replacing the absent Hans. He had only joined the company at the beginning of the same week, and was already tasked to give Hans' talk on PostgreSQL as Open Source. Of course he did well.
Next was Tanmay Sinha from Readyset. They are building a system that caches expensive SQL queries and selectively invalidates the cache whenever any data used by these queries changes. Whenever actually fixing the application isn't feasible, that system looks like an interesting alternative to manually maintaining materialized views, or perhaps using pg_ivm. After lunch, I went to Federico Campoli's Mastering Index Performance, but really spent the time polishing the slides for my talk. I had given the original version at pgconf.de in Berlin in May, and the slides were still in German, so I had to do some translating. Luckily, most slides are just git commit messages, so the effort was manageable. The next slot was mine, talking about Modern VACUUM. I started with a recap of MVCC, vacuum and freezing in PostgreSQL, and then showed how over the past years, the system was updated to be more focused (the PostgreSQL 8.4 visibility map tells vacuum which pages to visit), faster (12 made autovacuum run 10 times faster by default), less scary (14 has an emergency mode where freezing switches to maximum speed if it runs out of time; 16 makes freezing create much less WAL) and more performant (17 makes vacuum use much less memory). In summary, there is still room for the DBA to tune some knobs (for example, the default autovacuum_max_workers=3 isn't much), but the vacuum default settings are pretty much okay these days for average workloads. Specific workloads still have a whopping 31 postgresql.conf settings at their disposal just for vacuum.
Right after my talk, there was another vacuum talk: When Autovacuum Met FinOps by Mayuresh Bagayatkar. He added practical advice on tuning the performance in cloud environments. Luckily, our contents did not overlap. After the coffee break, I was again room host, now for Floor Drees and Contributing to Postgres beyond code. She presented the various ways in which PostgreSQL is more than just the code in the Git repository: translators, web site, system administration, conference organizers, speakers, bloggers, advocates. As a member of the PostgreSQL Contributors Committee, I could only approve and we should closer cooperate in the future to make people's contributions to PostgreSQL more visible and give them the recognition they deserve.
That was already the end of the main talks and everyone rushed to the Orangerie for the lightning talks. My highlight was the Sheldrick Wildlife Trust. Tickets for the conference had included the option to donate for the elephants in Kenya, and the talk presented the trust's work in the elephant orphanage there. After the conference had officially closed, there was a bonus track: the Celebrity DB Deathmatch, aptly presented by Boriss Mejias. PostgreSQL, MongoDB, CloudDB and Oracle were competing for the grace of a developer. MongoDB couldn't stand the JSON workload, CloudDB was dismissed for handing out new invoices all the time, and Oracle had even brought a lawyer to the stage, but then lost control over a literally 10 meter long contract with too much fine print. In the end, PostgreSQL (played by Floor) won the love of the developer (played by our Svitlana Lytvynenko).
The day closed with a gathering at the Brandauer Schlossbr u - just at the other end of the castle ground, but still a 15min walk away. We enjoyed good beer and Kaiserschmarrn. I went back to the hotel a bit before midnight, but some extended that time quite some bit more. On Friday, my flight back was only in the afternoon, so I spent some time in morning in the Technikmuseum just next to the hotel, enjoying some old steam engines and a live demonstration of Tesla coils. This time, the flight actually went to the destination, and I was back in D sseldorf in the late afternoon.
In summary, pgday.at was a very nice event in a classy location. Thanks to the organizers for putting in all the work - and next year, Hans will hopefully be present in person! The post A Trip To Vienna With Surprises appeared first on CYBERTEC PostgreSQL Services & Support.

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