Search Results: "cas"

6 February 2024

Robert McQueen: Flathub: Pros and Cons of Direct Uploads

I attended FOSDEM last weekend and had the pleasure to participate in the Flathub / Flatpak BOF on Saturday. A lot of the session was used up by an extensive discussion about the merits (or not) of allowing direct uploads versus building everything centrally on Flathub s infrastructure, and related concerns such as automated security/dependency scanning. My original motivation behind the idea was essentially two things. The first was to offer a simpler way forward for applications that use language-specific build tools that resolve and retrieve their own dependencies from the internet. Flathub doesn t allow network access during builds, and so a lot of manual work and additional tooling is currently needed (see Python and Electron Flatpak guides). And the second was to offer a maybe more familiar flow to developers from other platforms who would just build something and then run another command to upload it to the store, without having to learn the syntax of a new build tool. There were many valid concerns raised in the room, and I think on reflection that this is still worth doing, but might not be as valuable a way forward for Flathub as I had initially hoped. Of course, for a proprietary application where Flathub never sees the source or where it s built, whether that binary is uploaded to us or downloaded by us doesn t change much. But for an FLOSS application, a direct upload driven by the developer causes a regression on a number of fronts. We re not getting too hung up on the malicious developer inserts evil code in the binary case because Flathub already works on the model of verifying the developer and the user makes a decision to trust that app we don t review the source after all. But we do lose other things such as our infrastructure building on multiple architectures, and visibility on whether the build environment or upload credentials have been compromised unbeknownst to the developer. There is now a manual review process for when apps change their metadata such as name, icon, license and permissions which would apply to any direct uploads as well. It was suggested that if only heavily sandboxed apps (eg no direct filesystem access without proper use of portals) were permitted to make direct uploads, the impact of such concerns might be somewhat mitigated by the sandboxing. However, it was also pointed out that my go-to example of Electron app developers can upload to Flathub with one command was also a bit of a fiction. At present, none of them would pass that stricter sandboxing requirement. Almost all Electron apps run old versions of Chromium with less complete portal support, needing sandbox escapes to function correctly, and Electron (and Chromium s) sandboxing still needs additional tooling/downstream patching to run inside a Flatpak. Buh-boh. I think for established projects who already ship their own binaries from their own centralised/trusted infrastructure, and for developers who have understandable sensitivities about binary integrity such such as encryption, password or financial tools, it s a definite improvement that we re able to set up direct uploads with such projects with less manual work. There are already quite a few applications including verified ones where the build recipe simply fetches a binary built elsewhere and unpacks it, and if this already done centrally by the developer, repeating the exercise on Flathub s server adds little value. However for the individual developer experience, I think we need to zoom out a bit and think about how to improve this from a tools and infrastructure perspective as we grow Flathub, and as we seek to raise funds for different sources for these improvements. I took notes for everything that was mentioned as a tooling limitation during the BOF, along with a few ideas about how we could improve things, and hope to share these soon as part of an RFP/RFI (Request For Proposals/Request for Information) process. We don t have funding yet but if we have some prospective collaborators to help refine the scope and estimate the cost/effort, we can use this to go and pursue funding opportunities.

1 February 2024

Russ Allbery: Review: System Collapse

Review: System Collapse, by Martha Wells
Series: Murderbot Diaries #7
Publisher: Tordotcom
Copyright: 2023
ISBN: 1-250-82698-5
Format: Kindle
Pages: 245
System Collapse is the second Murderbot novel. Including the novellas, it's the 7th in the series. Unlike Fugitive Telemetry, the previous novella that was out of chronological order, this is the direct sequel to Network Effect. A very direct sequel; it picks up just a few days after the previous novel ended. Needless to say, you should not start here. I was warned by other people and therefore re-read Network Effect immediately before reading System Collapse. That was an excellent idea, since this novel opens with a large cast, no dramatis personae, not much in the way of a plot summary, and a lot of emotional continuity from the previous novel. I would grumble about this more, like I have in other reviews, but I thoroughly enjoyed re-reading Network Effect and appreciated the excuse.
ART-drone said, I wouldn t recommend it. I lack a sense of proportional response. I don t advise engaging with me on any level.
Saying much about the plot of this book without spoiling Network Effect and the rest of the series is challenging. Murderbot is suffering from the aftereffects of the events of the previous book more than it expected or would like to admit. It and its humans are in the middle of a complicated multi-way negotiation with some locals, who the corporates are trying to exploit. One of the difficulties in that negotiation is getting people to believe that the corporations are as evil as they actually are, a plot element that has a depressing amount in common with current politics. Meanwhile, Murderbot is trying to keep everyone alive. I loved Network Effect, but that was primarily for the social dynamics. The planet that was central to the novel was less interesting, so another (short) novel about the same planet was a bit of a disappointment. This does give Wells a chance to show in more detail what Murderbot's new allies have been up to, but there is a lot of speculative exploration and detailed descriptions of underground tunnels that I found less compelling than the relationship dynamics of the previous book. (Murderbot, on the other hand, would much prefer exploring creepy abandoned tunnels to talking about its feelings.) One of the things this series continues to do incredibly well, though, is take non-human intelligence seriously in a world where the humans mostly don't. It perfectly fills a gap between Star Wars, where neither the humans nor the story take non-human intelligences seriously (hence the creepy slavery vibes as soon as you start paying attention to droids), and the Culture, where both humans and the story do. The corporates (the bad guys in this series) treat non-human intelligences the way Star Wars treats droids. The good guys treat Murderbot mostly like a strange human, which is better but still wrong, and still don't notice the numerous other machine intelligences. But Wells, as the author, takes all of the non-human characters seriously, which means there are complex and fascinating relationships happening at a level of the story that the human characters are mostly unaware of. I love that Murderbot rarely bothers to explain; if the humans are too blinkered to notice, that's their problem. About halfway into the story, System Collapse hits its stride, not coincidentally at the point where Murderbot befriends some new computers. The rest of the book is great. This was not as good as Network Effect. There is a bit less competence porn at the start, and although that's for good in-story reasons I still missed it. Murderbot's redaction of things it doesn't want to talk about got a bit annoying before it finally resolved. And I was not sufficiently interested in this planet to want to spend two novels on it, at least without another major revelation that didn't come. But it's still a Murderbot novel, which means it has the best first-person narrative voice I've ever read, some great moments, and possibly the most compelling and varied presentation of computer intelligence in science fiction at the moment.
There was no feed ID, but AdaCol2 supplied the name Lucia and when I asked it for more info, the gender signifier bb (which didn t translate) and he/him pronouns. (I asked because the humans would bug me for the information; I was as indifferent to human gender as it was possible to be without being unconscious.)
This is not a series to read out of order, but if you have read this far, you will continue to be entertained. You don't need me to tell you this nearly everyone reviewing science fiction is saying it but this series is great and you should read it. Rating: 8 out of 10

30 January 2024

Matthew Palmer: Why Certificate Lifecycle Automation Matters

If you ve perused the ActivityPub feed of certificates whose keys are known to be compromised, and clicked on the Show More button to see the name of the certificate issuer, you may have noticed that some issuers seem to come up again and again. This might make sense after all, if a CA is issuing a large volume of certificates, they ll be seen more often in a list of compromised certificates. In an attempt to see if there is anything that we can learn from this data, though, I did a bit of digging, and came up with some illuminating results.

The Procedure I started off by finding all the unexpired certificates logged in Certificate Transparency (CT) logs that have a key that is in the pwnedkeys database as having been publicly disclosed. From this list of certificates, I removed duplicates by matching up issuer/serial number tuples, and then reduced the set by counting the number of unique certificates by their issuer. This gave me a list of the issuers of these certificates, which looks a bit like this:
/C=BE/O=GlobalSign nv-sa/CN=AlphaSSL CA - SHA256 - G4
/C=GB/ST=Greater Manchester/L=Salford/O=Sectigo Limited/CN=Sectigo RSA Domain Validation Secure Server CA
/C=GB/ST=Greater Manchester/L=Salford/O=Sectigo Limited/CN=Sectigo RSA Organization Validation Secure Server CA
/C=US/ST=Arizona/L=Scottsdale/O=GoDaddy.com, Inc./OU=http://certs.godaddy.com/repository//CN=Go Daddy Secure Certificate Authority - G2
/C=US/ST=Arizona/L=Scottsdale/O=Starfield Technologies, Inc./OU=http://certs.starfieldtech.com/repository//CN=Starfield Secure Certificate Authority - G2
/C=AT/O=ZeroSSL/CN=ZeroSSL RSA Domain Secure Site CA
/C=BE/O=GlobalSign nv-sa/CN=GlobalSign GCC R3 DV TLS CA 2020
Rather than try to work with raw issuers (because, as Andrew Ayer says, The SSL Certificate Issuer Field is a Lie), I mapped these issuers to the organisations that manage them, and summed the counts for those grouped issuers together.

The Data
Lieutenant Commander Data from Star Trek: The Next Generation Insert obligatory "not THAT data" comment here
The end result of this work is the following table, sorted by the count of certificates which have been compromised by exposing their private key:
IssuerCompromised Count
Sectigo170
ISRG (Let's Encrypt)161
GoDaddy141
DigiCert81
GlobalSign46
Entrust3
SSL.com1
If you re familiar with the CA ecosystem, you ll probably recognise that the organisations with large numbers of compromised certificates are also those who issue a lot of certificates. So far, nothing particularly surprising, then. Let s look more closely at the relationships, though, to see if we can get more useful insights.

Volume Control Using the issuance volume report from crt.sh, we can compare issuance volumes to compromise counts, to come up with a compromise rate . I m using the Unexpired Precertificates colume from the issuance volume report, as I feel that s the number that best matches the certificate population I m examining to find compromised certificates. To maintain parity with the previous table, this one is still sorted by the count of certificates that have been compromised.
IssuerIssuance VolumeCompromised CountCompromise Rate
Sectigo88,323,0681701 in 519,547
ISRG (Let's Encrypt)315,476,4021611 in 1,959,480
GoDaddy56,121,4291411 in 398,024
DigiCert144,713,475811 in 1,786,586
GlobalSign1,438,485461 in 31,271
Entrust23,16631 in 7,722
SSL.com171,81611 in 171,816
If we now sort this table by compromise rate, we can see which organisations have the most (and least) leakiness going on from their customers:
IssuerIssuance VolumeCompromised CountCompromise Rate
Entrust23,16631 in 7,722
GlobalSign1,438,485461 in 31,271
SSL.com171,81611 in 171,816
GoDaddy56,121,4291411 in 398,024
Sectigo88,323,0681701 in 519,547
DigiCert144,713,475811 in 1,786,586
ISRG (Let's Encrypt)315,476,4021611 in 1,959,480
By grouping by order-of-magnitude in the compromise rate, we can identify three bands :
  • The Super Leakers: Customers of Entrust and GlobalSign seem to love to lose control of their private keys. For Entrust, at least, though, the small volumes involved make the numbers somewhat untrustworthy. The three compromised certificates could very well belong to just one customer, for instance. I m not aware of anything that GlobalSign does that would make them such an outlier, either, so I m inclined to think they just got unlucky with one or two customers, but as CAs don t include customer IDs in the certificates they issue, it s not possible to say whether that s the actual cause or not.
  • The Regular Leakers: Customers of SSL.com, GoDaddy, and Sectigo all have compromise rates in the 1-in-hundreds-of-thousands range. Again, the low volumes of SSL.com make the numbers somewhat unreliable, but the other two organisations in this group have large enough numbers that we can rely on that data fairly well, I think.
  • The Low Leakers: Customers of DigiCert and Let s Encrypt are at least three times less likely than customers of the regular leakers to lose control of their private keys. Good for them!
Now we have some useful insights we can think about.

Why Is It So?
Professor Julius Sumner Miller If you don't know who Professor Julius Sumner Miller is, I highly recommend finding out
All of the organisations on the list, with the exception of Let s Encrypt, are what one might term traditional CAs. To a first approximation, it s reasonable to assume that the vast majority of the customers of these traditional CAs probably manage their certificates the same way they have for the past two decades or more. That is, they generate a key and CSR, upload the CSR to the CA to get a certificate, then copy the cert and key somewhere. Since humans are handling the keys, there s a higher risk of the humans using either risky practices, or making a mistake, and exposing the private key to the world. Let s Encrypt, on the other hand, issues all of its certificates using the ACME (Automatic Certificate Management Environment) protocol, and all of the Let s Encrypt documentation encourages the use of software tools to generate keys, issue certificates, and install them for use. Given that Let s Encrypt has 161 compromised certificates currently in the wild, it s clear that the automation in use is far from perfect, but the significantly lower compromise rate suggests to me that lifecycle automation at least reduces the rate of key compromise, even though it doesn t eliminate it completely.

Explaining the Outlier The difference in presumed issuance practices would seem to explain the significant difference in compromise rates between Let s Encrypt and the other organisations, if it weren t for one outlier. This is a largely traditional CA, with the manual-handling issues that implies, but with a compromise rate close to that of Let s Encrypt. We are, of course, talking about DigiCert. The thing about DigiCert, that doesn t show up in the raw numbers from crt.sh, is that DigiCert manages the issuance of certificates for several of the biggest hosted TLS providers, such as CloudFlare and AWS. When these services obtain a certificate from DigiCert on their customer s behalf, the private key is kept locked away, and no human can (we hope) get access to the private key. This is supported by the fact that no certificates identifiably issued to either CloudFlare or AWS appear in the set of certificates with compromised keys. When we ask for all certificates issued by DigiCert , we get both the certificates issued to these big providers, which are very good at keeping their keys under control, as well as the certificates issued to everyone else, whose key handling practices may not be quite so stringent. It s possible, though not trivial, to account for certificates issued to these hosted TLS providers, because the certificates they use are issued from intermediates branded to those companies. With the crt.sh psql interface we can run this query to get the total number of unexpired precertificates issued to these managed services:
SELECT SUM(sub.NUM_ISSUED[2] - sub.NUM_EXPIRED[2])
  FROM (
    SELECT ca.name, max(coalesce(coalesce(nullif(trim(cc.SUBORDINATE_CA_OWNER), ''), nullif(trim(cc.CA_OWNER), '')), cc.INCLUDED_CERTIFICATE_OWNER)) as OWNER,
           ca.NUM_ISSUED, ca.NUM_EXPIRED
      FROM ccadb_certificate cc, ca_certificate cac, ca
     WHERE cc.CERTIFICATE_ID = cac.CERTIFICATE_ID
       AND cac.CA_ID = ca.ID
  GROUP BY ca.ID
  ) sub
 WHERE sub.name ILIKE '%Amazon%' OR sub.name ILIKE '%CloudFlare%' AND sub.owner = 'DigiCert';
The number I get from running that query is 104,316,112, which should be subtracted from DigiCert s total issuance figures to get a more accurate view of what DigiCert s regular customers do with their private keys. When I do this, the compromise rates table, sorted by the compromise rate, looks like this:
IssuerIssuance VolumeCompromised CountCompromise Rate
Entrust23,16631 in 7,722
GlobalSign1,438,485461 in 31,271
SSL.com171,81611 in 171,816
GoDaddy56,121,4291411 in 398,024
"Regular" DigiCert40,397,363811 in 498,732
Sectigo88,323,0681701 in 519,547
All DigiCert144,713,475811 in 1,786,586
ISRG (Let's Encrypt)315,476,4021611 in 1,959,480
In short, it appears that DigiCert s regular customers are just as likely as GoDaddy or Sectigo customers to expose their private keys.

What Does It All Mean? The takeaway from all this is fairly straightforward, and not overly surprising, I believe.

The less humans have to do with certificate issuance, the less likely they are to compromise that certificate by exposing the private key. While it may not be surprising, it is nice to have some empirical evidence to back up the common wisdom. Fully-managed TLS providers, such as CloudFlare, AWS Certificate Manager, and whatever Azure s thing is called, is the platonic ideal of this principle: never give humans any opportunity to expose a private key. I m not saying you should use one of these providers, but the security approach they have adopted appears to be the optimal one, and should be emulated universally. The ACME protocol is the next best, in that there are a variety of standardised tools widely available that allow humans to take themselves out of the loop, but it s still possible for humans to handle (and mistakenly expose) key material if they try hard enough. Legacy issuance methods, which either cannot be automated, or require custom, per-provider automation to be developed, appear to be at least four times less helpful to the goal of avoiding compromise of the private key associated with a certificate.

Humans Are, Of Course, The Problem
Bender, the robot from Futurama, asking if we'd like to kill all humans No thanks, Bender, I'm busy tonight
This observation that if you don t let humans near keys, they don t get leaked is further supported by considering the biggest issuers by volume who have not issued any certificates whose keys have been compromised: Google Trust Services (fourth largest issuer overall, with 57,084,529 unexpired precertificates), and Microsoft Corporation (sixth largest issuer overall, with 22,852,468 unexpired precertificates). It appears that somewhere between most and basically all of the certificates these organisations issue are to customers of their public clouds, and my understanding is that the keys for these certificates are managed in same manner as CloudFlare and AWS the keys are locked away where humans can t get to them. It should, of course, go without saying that if a human can never have access to a private key, it makes it rather difficult for a human to expose it. More broadly, if you are building something that handles sensitive or secret data, the more you can do to keep humans out of the loop, the better everything will be.

Your Support is Appreciated If you d like to see more analysis of how key compromise happens, and the lessons we can learn from examining billions of certificates, please show your support by buying me a refreshing beverage. Trawling CT logs is thirsty work.

Appendix: Methodology Limitations In the interests of clarity, I feel it s important to describe ways in which my research might be flawed. Here are the things I know of that may have impacted the accuracy, that I couldn t feasibly account for.
  • Time Periods: Because time never stops, there is likely to be some slight mismatches in the numbers obtained from the various data sources, because they weren t collected at exactly the same moment.
  • Issuer-to-Organisation Mapping: It s possible that the way I mapped issuers to organisations doesn t match exactly with how crt.sh does it, meaning that counts might be skewed. I tried to minimise that by using the same data sources (the CCADB AllCertificates report) that I believe that crt.sh uses for its mapping, but I cannot be certain of a perfect match.
  • Unwarranted Grouping: I ve drawn some conclusions about the practices of the various organisations based on their general approach to certificate issuance. If a particular subordinate CA that I ve grouped into the parent organisation is managed in some unusual way, that might cause my conclusions to be erroneous. I was able to fairly easily separate out CloudFlare, AWS, and Azure, but there are almost certainly others that I didn t spot, because hoo boy there are a lot of intermediate CAs out there.

28 January 2024

Niels Thykier: Annotating the Debian packaging directory

In my previous blog post Providing online reference documentation for debputy, I made a point about how debhelper documentation was suboptimal on account of being static rather than online. The thing is that debhelper is not alone in this problem space, even if it is a major contributor to the number of packaging files you have to to know about. If we look at the "competition" here such as Fedora and Arch Linux, they tend to only have one packaging file. While most Debian people will tell you a long list of cons about having one packaging file (such a Fedora's spec file being 3+ domain specific languages "mashed" into one file), one major advantage is that there is only "the one packaging file". You only need to remember where to find the documentation for one file, which is great when you are running on wetware with limited storage capacity. Which means as a newbie, you can dedicate less mental resources to tracking multiple files and how they interact and more effort understanding the "one file" at hand. I started by asking myself how can we in Debian make the packaging stack more accessible to newcomers? Spoiler alert, I dug myself into rabbit hole and ended up somewhere else than where I thought I was going. I started by wanting to scan the debian directory and annotate all files that I could with documentation links. The logic was that if debputy could do that for you, then you could spend more mental effort elsewhere. So I combined debputy's packager provided files detection with a static list of files and I quickly had a good starting point for debputy-based packages.
Adding (non-static) dpkg and debhelper files to the mix Now, I could have closed the topic here and said "Look, I did debputy files plus couple of super common files". But I decided to take it a bit further. I added support for handling some dpkg files like packager provided files (such as debian/substvars and debian/symbols). But even then, we all know that debhelper is the big hurdle and a major part of the omission... In another previous blog post (A new Debian package helper: debputy), I made a point about how debputy could list all auxiliary files while debhelper could not. This was exactly the kind of feature that I would need for this feature, if this feature was to cover debhelper. Now, I also remarked in that blog post that I was not willing to maintain such a list. Also, I may have ranted about static documentation being unhelpful for debhelper as it excludes third-party provided tooling. Fortunately, a recent update to dh_assistant had provided some basic plumbing for loading dh sequences. This meant that getting a list of all relevant commands for a source package was a lot easier than it used to be. Once you have a list of commands, it would be possible to check all of them for dh's NOOP PROMISE hints. In these hints, a command can assert it does nothing if a given pkgfile is not present. This lead to the new dh_assistant list-guessed-dh-config-files command that will list all declared pkgfiles and which helpers listed them. With this combined feature set in place, debputy could call dh_assistant to get a list of pkgfiles, pretend they were packager provided files and annotate those along with manpage for the relevant debhelper command. The exciting thing about letting debpputy resolve the pkgfiles is that debputy will resolve "named" files automatically (debhelper tools will only do so when --name is passed), so it is much more likely to detect named pkgfiles correctly too. Side note: I am going to ignore the elephant in the room for now, which is dh_installsystemd and its package@.service files and the wide-spread use of debian/foo.service where there is no package called foo. For the latter case, the "proper" name would be debian/pkg.foo.service. With the new dh_assistant feature done and added to debputy, debputy could now detect the ubiquitous debian/install file. Excellent. But less great was that the very common debian/docs file was not. Turns out that dh_installdocs cannot be skipped by dh, so it cannot have NOOP PROMISE hints. Meh... Well, dh_assistant could learn about a new INTROSPECTABLE marker in addition to the NOOP PROMISE and then I could sprinkle that into a few commands. Indeed that worked and meant that debian/postinst (etc.) are now also detectable. At this point, debputy would be able to identify a wide range of debhelper related configuration files in debian/ and at least associate each of them with one or more commands. Nice, surely, this would be a good place to stop, right...?
Adding more metadata to the files The debhelper detected files only had a command name and manpage URI to that command. It would be nice if we could contextualize this a bit more. Like is this file installed into the package as is like debian/pam or is it a file list to be processed like debian/install. To make this distinction, I could add the most common debhelper file types to my static list and then merge the result together. Except, I do not want to maintain a full list in debputy. Fortunately, debputy has a quite extensible plugin infrastructure, so added a new plugin feature to provide this kind of detail and now I can outsource the problem! I split my definitions into two and placed the generic ones in the debputy-documentation plugin and moved the debhelper related ones to debhelper-documentation. Additionally, third-party dh addons could provide their own debputy plugin to add context to their configuration files. So, this gave birth file categories and configuration features, which described each file on different fronts. As an example, debian/gbp.conf could be tagged as a maint-config to signal that it is not directly related to the package build but more of a tool or style preference file. On the other hand, debian/install and debian/debputy.manifest would both be tagged as a pkg-helper-config. Files like debian/pam were tagged as ppf-file for packager provided file and so on. I mentioned configuration features above and those were added because, I have had a beef with debhelper's "standard" configuration file format as read by filearray and filedoublearray. They are often considered simple to understand, but it is hard to know how a tool will actually read the file. As an example, consider the following:
  • Will the debhelper use filearray, filedoublearray or none of them to read the file? This topic has about 2 bits of entropy.
  • Will the config file be executed if it is marked executable assuming you are using the right compat level? If it is executable, does dh-exec allow renaming for this file? This topic adds 1 or 2 bit of entropy depending on the context.
  • Will the config file be subject to glob expansions? This topic sounds like a boolean but is a complicated mess. The globs can be handled either by debhelper as it parses the file for you. In this case, the globs are applied to every token. However, this is not what dh_install does. Here the last token on each line is supposed to be a directory and therefore not subject to globs. Therefore, dh_install does the globbing itself afterwards but only on part of the tokens. So that is about 2 bits of entropy more. Actually, it gets worse...
    • If the file is executed, debhelper will refuse to expand globs in the output of the command, which was a deliberate design choice by the original debhelper maintainer took when he introduced the feature in debhelper/8.9.12. Except, dh_install feature interacts with the design choice and does enable glob expansion in the tool output, because it does so manually after its filedoublearray call.
So these "simple" files have way too many combinations of how they can be interpreted. I figured it would be helpful if debputy could highlight these difference, so I added support for those as well. Accordingly, debian/install is tagged with multiple tags including dh-executable-config and dh-glob-after-execute. Then, I added a datatable of these tags, so it would be easy for people to look up what they meant. Ok, this seems like a closed deal, right...?
Context, context, context However, the dh-executable-config tag among other are only applicable in compat 9 or later. It does not seem newbie friendly if you are told that this feature exist, but then have to read in the extended description that that it actually does not apply to your package. This problem seems fixable. Thanks to dh_assistant, it is easy to figure out which compat level the package is using. Then tweak some metadata to enable per compat level rules. With that tags like dh-executable-config only appears for packages using compat 9 or later. Also, debputy should be able to tell you where packager provided files like debian/pam are installed. We already have the logic for packager provided files that debputy supports and I am already using debputy engine for detecting the files. If only the plugin provided metadata gave me the install pattern, debputy would be able tell you where this file goes in the package. Indeed, a bit of tweaking later and setting install-pattern to usr/lib/pam.d/ name , debputy presented me with the correct install-path with the package name placing the name placeholder. Now, I have been using debian/pam as an example, because debian/pam is installed into usr/lib/pam.d in compat 14. But in earlier compat levels, it was installed into etc/pam.d. Well, I already had an infrastructure for doing compat file tags. Off we go to add install-pattern to the complat level infrastructure and now changing the compat level would change the path. Great. (Bug warning: The value is off-by-one in the current version of debhelper. This is fixed in git) Also, while we are in this install-pattern business, a number of debhelper config files causes files to be installed into a fixed directory. Like debian/docs which causes file to be installed into /usr/share/docs/ package . Surely, we can expand that as well and provide that bit of context too... and done. (Bug warning: The code currently does not account for the main documentation package context) It is rather common pattern for people to do debian/foo.in files, because they want to custom generation of debian/foo. Which means if you have debian/foo you get "Oh, let me tell you about debian/foo ". Then you rename it to debian/foo.in and the result is "debian/foo.in is a total mystery to me!". That is suboptimal, so lets detect those as well as if they were the original file but add a tag saying that they are a generate template and which file we suspect it generates. Finally, if you use debputy, almost all of the standard debhelper commands are removed from the sequence, since debputy replaces them. It would be weird if these commands still contributed configuration files when they are not actually going to be invoked. This mostly happened naturally due to the way the underlying dh_assistant command works. However, any file mentioned by the debhelper-documentation plugin would still appear unfortunately. So off I went to filter the list of known configuration files against which dh_ commands that dh_assistant thought would be used for this package.
Wrapping it up I was several layers into this and had to dig myself out. I have ended up with a lot of data and metadata. But it was quite difficult for me to arrange the output in a user friendly manner. However, all this data did seem like it would be useful any tool that wants to understand more about the package. So to get out of the rabbit hole, I for now wrapped all of this into JSON and now we have a debputy tool-support annotate-debian-directory command that might be useful for other tools. To try it out, you can try the following demo: In another day, I will figure out how to structure this output so it is useful for non-machine consumers. Suggestions are welcome. :)
Limitations of the approach As a closing remark, I should probably remind people that this feature relies heavily on declarative features. These include:
  • When determining which commands are relevant, using Build-Depends: dh-sequence-foo is much more reliable than configuring it via the Turing complete configuration we call debian/rules.
  • When debhelper commands use NOOP promise hints, dh_assistant can "see" the config files listed those hints, meaning the file will at least be detected. For new introspectable hint and the debputy plugin, it is probably better to wait until the dust settles a bit before adding any of those.
You can help yourself and others to better results by using the declarative way rather than using debian/rules, which is the bane of all introspection!

25 January 2024

Joachim Breitner: GHC Steering Committee Retrospective

After seven years of service as member and secretary on the GHC Steering Committee, I have resigned from that role. So this is a good time to look back and retrace the formation of the GHC proposal process and committee. In my memory, I helped define and shape the proposal process, optimizing it for effectiveness and throughput, but memory can be misleading, and judging from the paper trail in my email archives, this was indeed mostly Ben Gamari s and Richard Eisenberg s achievement: Already in Summer of 2016, Ben Gamari set up the ghc-proposals Github repository with a sketch of a process and sent out a call for nominations on the GHC user s mailing list, which I replied to. The Simons picked the first set of members, and in the fall of 2016 we discussed the committee s by-laws and procedures. As so often, Richard was an influential shaping force here.

Three ingredients For example, it was him that suggested that for each proposal we have one committee member be the Shepherd , overseeing the discussion. I believe this was one ingredient for the process effectiveness: There is always one person in charge, and thus we avoid the delays incurred when any one of a non-singleton set of volunteers have to do the next step (and everyone hopes someone else does it). The next ingredient was that we do not usually require a vote among all members (again, not easy with volunteers with limited bandwidth and occasional phases of absence). Instead, the shepherd makes a recommendation (accept/reject), and if the other committee members do not complain, this silence is taken as consent, and we come to a decision. It seems this idea can also be traced back on Richard, who suggested that once a decision is requested, the shepherd [generates] consensus. If consensus is elusive, then we vote. At the end of the year we agreed and wrote down these rules, created the mailing list for our internal, but publicly archived committee discussions, and began accepting proposals, starting with Adam Gundry s OverloadedRecordFields. At that point, there was no secretary role yet, so how I did become one? It seems that in February 2017 I started to clean-up and refine the process documentation, fixing bugs in the process (like requiring authors to set Github labels when they don t even have permissions to do that). This in particular meant that someone from the committee had to manually handle submissions and so on, and by the aforementioned principle that at every step there ought to be exactly one person in change, the role of a secretary followed naturally. In the email in which I described that role I wrote:
Simon already shoved me towards picking up the secretary hat, to reduce load on Ben.
So when I merged the updated process documentation, I already listed myself secretary . It wasn t just Simon s shoving that put my into the role, though. I dug out my original self-nomination email to Ben, and among other things I wrote:
I also hope that there is going to be clear responsibilities and a clear workflow among the committee. E.g. someone (possibly rotating), maybe called the secretary, who is in charge of having an initial look at proposals and then assigning it to a member who shepherds the proposal.
So it is hardly a surprise that I became secretary, when it was dear to my heart to have a smooth continuous process here. I am rather content with the result: These three ingredients single secretary, per-proposal shepherds, silence-is-consent helped the committee to be effective throughout its existence, even as every once in a while individual members dropped out.

Ulterior motivation I must admit, however, there was an ulterior motivation behind me grabbing the secretary role: Yes, I did want the committee to succeed, and I did want that authors receive timely, good and decisive feedback on their proposals but I did not really want to have to do that part. I am, in fact, a lousy proposal reviewer. I am too generous when reading proposals, and more likely mentally fill gaps in a specification rather than spotting them. Always optimistically assuming that the authors surely know what they are doing, rather than critically assessing the impact, the implementation cost and the interaction with other language features. And, maybe more importantly: why should I know which changes are good and which are not so good in the long run? Clearly, the authors cared enough about a proposal to put it forward, so there is some need and I do believe that Haskell should stay an evolving and innovating language but how does this help me decide about this or that particular feature. I even, during the formation of the committee, explicitly asked that we write down some guidance on Vision and Guideline ; do we want to foster change or innovation, or be selective gatekeepers? Should we accept features that are proven to be useful, or should we accept features so that they can prove to be useful? This discussion, however, did not lead to a concrete result, and the assessment of proposals relied on the sum of each member s personal preference, expertise and gut feeling. I am not saying that this was a mistake: It is hard to come up with a general guideline here, and even harder to find one that does justice to each individual proposal. So the secret motivation for me to grab the secretary post was that I could contribute without having to judge proposals. Being secretary allowed me to assign most proposals to others to shepherd, and only once in a while myself took care of a proposal, when it seemed to be very straight-forward. Sneaky, ain t it?

7 Years later For years to come I happily played secretary: When an author finished their proposal and public discussion ebbed down they would ping me on GitHub, I would pick a suitable shepherd among the committee and ask them to judge the proposal. Eventually, the committee would come to a conclusion, usually by implicit consent, sometimes by voting, and I d merge the pull request and update the metadata thereon. Every few months I d summarize the current state of affairs to the committee (what happened since the last update, which proposals are currently on our plate), and once per year gathered the data for Simon Peyton Jones annually GHC Status Report. Sometimes some members needed a nudge or two to act. Some would eventually step down, and I d sent around a call for nominations and when the nominations came in, distributed them off-list among the committee and tallied the votes. Initially, that was exciting. For a long while it was a pleasant and rewarding routine. Eventually, it became a mere chore. I noticed that I didn t quite care so much anymore about some of the discussion, and there was a decent amount of naval-gazing, meta-discussions and some wrangling about claims of authority that was probably useful and necessary, but wasn t particularly fun. I also began to notice weaknesses in the processes that I helped shape: We could really use some more automation for showing proposal statuses, notifying people when they have to act, and nudging them when they don t. The whole silence-is-assent approach is good for throughput, but not necessary great for quality, and maybe the committee members need to be pushed more firmly to engage with each proposal. Like GHC itself, the committee processes deserve continuous refinement and refactoring, and since I could not muster the motivation to change my now well-trod secretarial ways, it was time for me to step down. Luckily, Adam Gundry volunteered to take over, and that makes me feel much less bad for quitting. Thanks for that! And although I am for my day job now enjoying a language that has many of the things out of the box that for Haskell are still only language extensions or even just future proposals (dependent types, BlockArguments, do notation with ( foo) expressions and Unicode), I m still around, hosting the Haskell Interlude Podcast, writing on this blog and hanging out at ZuriHac etc.

24 January 2024

Louis-Philippe V ronneau: Montreal Subway Foot Traffic Data, 2023 edition

For the fifth year in a row, I've asked Soci t de Transport de Montr al, Montreal's transit agency, for the foot traffic data of Montreal's subway. By clicking on a subway station, you'll be redirected to a graph of the station's foot traffic. Licences

22 January 2024

Russell Coker: Storage Trends 2024

It has been less than a year since my last post about storage trends [1] and enough has changed to make it worth writing again. My previous analysis was that for <2TB only SSD made sense, for 4TB SSD made sense for business use while hard drives were still a good option for home use, and for 8TB+ hard drives were clearly the best choice for most uses. I will start by looking at MSY prices, they aren't the cheapest (you can get cheaper online) but they are competitive and they make it easy to compare the different options. I'll also compare the cheapest options in each size, there are more expensive options but usually if you want to pay more then the performance benefits of SSD (both SATA and NVMe) are even more appealing. All prices are in Australian dollars and of parts that are readily available in Australia, but the relative prices of the parts are probably similar in most countries. The main issue here is when to use SSD and when to use hard disks, and then if SSD is chosen which variety to use. Small Storage For my last post the cheapest storage devices from MSY were $19 for a 128G SSD, now it s $24 for a 128G SSD or NVMe device. I don t think the Australian dollar has dropped much against foreign currencies, so I guess this is partly companies wanting more profits and partly due to the demand for more storage. Items that can t sell in quantity need higher profit margins if they are to have them in stock. 500G SSDs are around $33 and 500G NVMe devices for $36 so for most use cases it wouldn t make sense to buy anything smaller than 500G. The cheapest hard drive is $45 for a 1TB disk. A 1TB SATA SSD costs $61 and a 1TB NVMe costs $79. So 1TB disks aren t a good option for any use case. A 2TB hard drive is $89. A 2TB SATA SSD is $118 and a 2TB NVMe is $145. I don t think the small savings you can get from using hard drives makes them worth using for 2TB. For most people if you have a system that s important to you then $145 on storage isn t a lot to spend. It seems hardly worth buying less than 2TB of storage, even for a laptop. Even if you don t use all the space larger storage devices tend to support more writes before wearing out so you still gain from it. A 2TB NVMe device you buy for a laptop now could be used in every replacement laptop for the next 10 years. I only have 512G of storage in my laptop because I have a collection of SSD/NVMe devices that have been replaced in larger systems, so the 512G is essentially free for my laptop as I bought a larger device for a server. For small business use it doesn t make sense to buy anything smaller than 2TB for any system other than a router. If you buy smaller devices then you will sometimes have to pay people to install bigger ones and when the price is $145 it s best to just pay that up front and be done with it. Medium Storage A 4TB hard drive is $135. A 4TB SATA SSD is $319 and a 4TB NVMe is $299. The prices haven t changed a lot since last year, but a small increase in hard drive prices and a small decrease in SSD prices makes SSD more appealing for this market segment. A common size range for home servers and small business servers is 4TB or 8TB of storage. To do that on SSD means about $600 for 4TB of RAID-1 or $900 for 8TB of RAID-5/RAID-Z. That s quite affordable for that use. For 8TB of less important storage a 8TB hard drive costs $239 and a 8TB SATA SSD costs $899 so a hard drive clearly wins for the specific case of non-RAID single device storage. Note that the U.2 devices are more competitive for 8TB than SATA but I included them in the next section because they are more difficult to install. Serious Storage With 8TB being an uncommon and expensive option for consumer SSDs the cheapest price is for multiple 4TB devices. To have multiple NVMe devices in one PCIe slot you need PCIe bifurcation (treating the PCIe slot as multiple slots). Most of the machines I use don t support bifurcation and most affordable systems with ECC RAM don t have it. For cheap NVMe type storage there are U.2 devices (the enterprise form of NVMe). Until recently they were too expensive to use for desktop systems but now there are PCIe cards for internal U.2 devices, $14 for a card that takes a single U.2 is a common price on AliExpress and prices below $600 for a 7.68TB U.2 device are common that s cheaper on a per-TB basis than SATA SSD and NVMe! There are PCIe cards that take up to 4*U.2 devices (which probably require bifurcation) which means you could have 8+ U.2 devices in one not particularly high end PC for 56TB of RAID-Z NVMe storage. Admittedly $4200 for 56TB is moderately expensive, but it s in the price range for a small business server or a high end home server. A more common configuration might be 2*7.68TB U.2 on a single PCIe card (or 2 cards if you don t have bifurcation) for 7.68TB of RAID-1 storage. For SATA SSD AliExpress has a 6*2.5 hot-swap device that fits in a 5.25 bay for $63, so if you have 2*5.25 bays you could have 12*4TB SSDs for 44TB of RAID-Z storage. That wouldn t be much cheaper than 8*7.68TB U.2 devices and would be slower and have less space. But it would be a good option if PCIe bifurcation isn t possible. 16TB SATA hard drives cost $559 which is almost exactly half the price per TB of U.2 storage. That doesn t seem like a good deal. If you want 16TB of RAID storage then 3*7.68TB U.2 devices only costs about 50% more than 2*16TB SATA disks. In most cases paying 50% more to get NVMe instead of hard disks is a good option. As sizes go above 16TB prices go up in a more than linear manner, I guess they don t sell much volume of larger drives. 15.36TB U.2 devices are on sale for about $1300, slightly more than twice the price of a 16TB disk. It s within the price range of small businesses and serious home users. Also it should be noted that the U.2 devices are designed for enterprise levels of reliability and the hard disk prices I m comparing to are the cheapest available. If NAS hard disks were compared then the price benefit of hard disks would be smaller. Probably the biggest problem with U.2 for most people is that it s an uncommon technology that few people have much experience with or spare parts for testing. Also you can t buy U.2 gear at your local computer store which might mean that you want to have spare parts on hand which is an extra expense. For enterprise use I ve recently been involved in discussions with a vendor that sells multiple petabyte arrays of NVMe. Apparently NVMe is cheap enough that there s no need to use anything else if you want a well performing file server. Do Hard Disks Make Sense? There are specific cases like comparing a 8TB hard disk to a 8TB SATA SSD or a 16TB hard disk to a 15.36TB U.2 device where hard disks have an apparent advantage. But when comparing RAID storage and counting the performance benefits of SSD the savings of using hard disks don t seem to be that great. Is now the time that hard disks are going to die in the market? If they can t get volume sales then prices will go up due to lack of economy of scale in manufacture and increased stock time for retailers. 8TB hard drives are now more expensive than they were 9 months ago when I wrote my previous post, has a hard drive price death spiral already started? SSDs are cheaper than hard disks at the smallest sizes, faster (apart from some corner cases with contiguous IO), take less space in a computer, and make less noise. At worst they are a bit over twice the cost per TB. But the most common requirements for storage are small enough and cheap enough that being twice as expensive as hard drives isn t a problem for most people. I predict that hard disks will become less popular in future and offer less of a price advantage. The vendors are talking about 50TB hard disks being available in future but right now you can fit more than 50TB of NVMe or U.2 devices in a volume less than that of a 3.5 hard disk so for storage density SSD can clearly win. Maybe in future hard disks will be used in arrays of 100TB devices for large scale enterprise storage. But for home users and small businesses the current sizes of SSD cover most uses. At the moment it seems that the one case where hard disks can really compare well is for backup devices. For backups you want large storage, good contiguous write speeds, and low prices so you can buy plenty of them. Further Issues The prices I ve compared for SATA SSD and NVMe devices are all based on the cheapest devices available. I think it s a bit of a market for lemons [2] as devices often don t perform as well as expected and the incidence of fake products purporting to be from reputable companies is high on the cheaper sites. So you might as well buy the cheaper devices. An advantage of the U.2 devices is that you know that they will be reliable and perform well. One thing that concerns me about SSDs is the lack of knowledge of their failure cases. Filesystems like ZFS were specifically designed to cope with common failure cases of hard disks and I don t think we have that much knowledge about how SSDs fail. But with 3 copies of metadata BTFS or ZFS should survive unexpected SSD failure modes. I still have some hard drives in my home server, they keep working well enough and the prices on SSDs keep dropping. But if I was buying new storage for such a server now I d get U.2. I wonder if tape will make a comeback for backup. Does anyone know of other good storage options that I missed?

20 January 2024

Niels Thykier: Making debputy: Writing declarative parsing logic

In this blog post, I will cover how debputy parses its manifest and the conceptual improvements I did to make parsing of the manifest easier. All instructions to debputy are provided via the debian/debputy.manifest file and said manifest is written in the YAML format. After the YAML parser has read the basic file structure, debputy does another pass over the data to extract the information from the basic structure. As an example, the following YAML file:
manifest-version: "0.1"
installations:
  - install:
      source: foo
      dest-dir: usr/bin
would be transformed by the YAML parser into a structure resembling:
 
  "manifest-version": "0.1",
  "installations": [
      
       "install":  
         "source": "foo",
         "dest-dir": "usr/bin",
        
      
  ]
 
This structure is then what debputy does a pass on to translate this into an even higher level format where the "install" part is translated into an InstallRule. In the original prototype of debputy, I would hand-write functions to extract the data that should be transformed into the internal in-memory high level format. However, it was quite tedious. Especially because I wanted to catch every possible error condition and report "You are missing the required field X at Y" rather than the opaque KeyError: X message that would have been the default. Beyond being tedious, it was also quite error prone. As an example, in debputy/0.1.4 I added support for the install rule and you should allegedly have been able to add a dest-dir: or an as: inside it. Except I crewed up the code and debputy was attempting to look up these keywords from a dict that could never have them. Hand-writing these parsers were so annoying that it demotivated me from making manifest related changes to debputy simply because I did not want to code the parsing logic. When I got this realization, I figured I had to solve this problem better. While reflecting on this, I also considered that I eventually wanted plugins to be able to add vocabulary to the manifest. If the API was "provide a callback to extract the details of whatever the user provided here", then the result would be bad.
  1. Most plugins would probably throw KeyError: X or ValueError style errors for quite a while. Worst case, they would end on my table because the user would have a hard time telling where debputy ends and where the plugins starts. "Best" case, I would teach debputy to say "This poor error message was brought to you by plugin foo. Go complain to them". Either way, it would be a bad user experience.
  2. This even assumes plugin providers would actually bother writing manifest parsing code. If it is that difficult, then just providing a custom file in debian might tempt plugin providers and that would undermine the idea of having the manifest be the sole input for debputy.
So beyond me being unsatisfied with the current situation, it was also clear to me that I needed to come up with a better solution if I wanted externally provided plugins for debputy. To put a bit more perspective on what I expected from the end result:
  1. It had to cover as many parsing errors as possible. An error case this code would handle for you, would be an error where I could ensure it sufficient degree of detail and context for the user.
  2. It should be type-safe / provide typing support such that IDEs/mypy could help you when you work on the parsed result.
  3. It had to support "normalization" of the input, such as
           # User provides
           - install: "foo"
           # Which is normalized into:
           - install:
               source: "foo"
4) It must be simple to tell  debputy  what input you expected.
At this point, I remembered that I had seen a Python (PYPI) package where you could give it a TypedDict and an arbitrary input (Sadly, I do not remember the name). The package would then validate the said input against the TypedDict. If the match was successful, you would get the result back casted as the TypedDict. If the match was unsuccessful, the code would raise an error for you. Conceptually, this seemed to be a good starting point for where I wanted to be. Then I looked a bit on the normalization requirement (point 3). What is really going on here is that you have two "schemas" for the input. One is what the programmer will see (the normalized form) and the other is what the user can input (the manifest form). The problem is providing an automatic normalization from the user input to the simplified programmer structure. To expand a bit on the following example:
# User provides
- install: "foo"
# Which is normalized into:
- install:
    source: "foo"
Given that install has the attributes source, sources, dest-dir, as, into, and when, how exactly would you automatically normalize "foo" (str) into source: "foo"? Even if the code filtered by "type" for these attributes, you would end up with at least source, dest-dir, and as as candidates. Turns out that TypedDict actually got this covered. But the Python package was not going in this direction, so I parked it here and started looking into doing my own. At this point, I had a general idea of what I wanted. When defining an extension to the manifest, the plugin would provide debputy with one or two definitions of TypedDict. The first one would be the "parsed" or "target" format, which would be the normalized form that plugin provider wanted to work on. For this example, lets look at an earlier version of the install-examples rule:
# Example input matching this typed dict.
#    
#       "source": ["foo"]
#       "into": ["pkg"]
#    
class InstallExamplesTargetFormat(TypedDict):
    # Which source files to install (dest-dir is fixed)
    sources: List[str]
    # Which package(s) that should have these files installed.
    into: NotRequired[List[str]]
In this form, the install-examples has two attributes - both are list of strings. On the flip side, what the user can input would look something like this:
# Example input matching this typed dict.
#    
#       "source": "foo"
#       "into": "pkg"
#    
#
class InstallExamplesManifestFormat(TypedDict):
    # Note that sources here is split into source (str) vs. sources (List[str])
    sources: NotRequired[List[str]]
    source: NotRequired[str]
    # We allow the user to write  into: foo  in addition to  into: [foo] 
    into: Union[str, List[str]]
FullInstallExamplesManifestFormat = Union[
    InstallExamplesManifestFormat,
    List[str],
    str,
]
The idea was that the plugin provider would use these two definitions to tell debputy how to parse install-examples. Pseudo-registration code could look something like:
def _handler(
    normalized_form: InstallExamplesTargetFormat,
) -> InstallRule:
    ...  # Do something with the normalized form and return an InstallRule.
concept_debputy_api.add_install_rule(
  keyword="install-examples",
  target_form=InstallExamplesTargetFormat,
  manifest_form=FullInstallExamplesManifestFormat,
  handler=_handler,
)
This was my conceptual target and while the current actual API ended up being slightly different, the core concept remains the same.
From concept to basic implementation Building this code is kind like swallowing an elephant. There was no way I would just sit down and write it from one end to the other. So the first prototype of this did not have all the features it has now. Spoiler warning, these next couple of sections will contain some Python typing details. When reading this, it might be helpful to know things such as Union[str, List[str]] being the Python type for either a str (string) or a List[str] (list of strings). If typing makes your head spin, these sections might less interesting for you. To build this required a lot of playing around with Python's introspection and typing APIs. My very first draft only had one "schema" (the normalized form) and had the following features:
  • Read TypedDict.__required_attributes__ and TypedDict.__optional_attributes__ to determine which attributes where present and which were required. This was used for reporting errors when the input did not match.
  • Read the types of the provided TypedDict, strip the Required / NotRequired markers and use basic isinstance checks based on the resulting type for str and List[str]. Again, used for reporting errors when the input did not match.
This prototype did not take a long (I remember it being within a day) and worked surprisingly well though with some poor error messages here and there. Now came the first challenge, adding the manifest format schema plus relevant normalization rules. The very first normalization I did was transforming into: Union[str, List[str]] into into: List[str]. At that time, source was not a separate attribute. Instead, sources was a Union[str, List[str]], so it was the only normalization I needed for all my use-cases at the time. There are two problems when writing a normalization. First is determining what the "source" type is, what the target type is and how they relate. The second is providing a runtime rule for normalizing from the manifest format into the target format. Keeping it simple, the runtime normalizer for Union[str, List[str]] -> List[str] was written as:
def normalize_into_list(x: Union[str, List[str]]) -> List[str]:
    return x if isinstance(x, list) else [x]
This basic form basically works for all types (assuming none of the types will have List[List[...]]). The logic for determining when this rule is applicable is slightly more involved. My current code is about 100 lines of Python code that would probably lose most of the casual readers. For the interested, you are looking for _union_narrowing in declarative_parser.py With this, when the manifest format had Union[str, List[str]] and the target format had List[str] the generated parser would silently map a string into a list of strings for the plugin provider. But with that in place, I had covered the basics of what I needed to get started. I was quite excited about this milestone of having my first keyword parsed without handwriting the parser logic (at the expense of writing a more generic parse-generator framework).
Adding the first parse hint With the basic implementation done, I looked at what to do next. As mentioned, at the time sources in the manifest format was Union[str, List[str]] and I considered to split into a source: str and a sources: List[str] on the manifest side while keeping the normalized form as sources: List[str]. I ended up committing to this change and that meant I had to solve the problem getting my parser generator to understand the situation:
# Map from
class InstallExamplesManifestFormat(TypedDict):
    # Note that sources here is split into source (str) vs. sources (List[str])
    sources: NotRequired[List[str]]
    source: NotRequired[str]
    # We allow the user to write  into: foo  in addition to  into: [foo] 
    into: Union[str, List[str]]
# ... into
class InstallExamplesTargetFormat(TypedDict):
    # Which source files to install (dest-dir is fixed)
    sources: List[str]
    # Which package(s) that should have these files installed.
    into: NotRequired[List[str]]
There are two related problems to solve here:
  1. How will the parser generator understand that source should be normalized and then mapped into sources?
  2. Once that is solved, the parser generator has to understand that while source and sources are declared as NotRequired, they are part of a exactly one of rule (since sources in the target form is Required). This mainly came down to extra book keeping and an extra layer of validation once the previous step is solved.
While working on all of this type introspection for Python, I had noted the Annotated[X, ...] type. It is basically a fake type that enables you to attach metadata into the type system. A very random example:
# For all intents and purposes,  foo  is a string despite all the  Annotated  stuff.
foo: Annotated[str, "hello world"] = "my string here"
The exciting thing is that you can put arbitrary details into the type field and read it out again in your introspection code. Which meant, I could add "parse hints" into the type. Some "quick" prototyping later (a day or so), I got the following to work:
# Map from
#      
#        "source": "foo"  # (or "sources": ["foo"])
#        "into": "pkg"
#      
class InstallExamplesManifestFormat(TypedDict):
    # Note that sources here is split into source (str) vs. sources (List[str])
    sources: NotRequired[List[str]]
    source: NotRequired[
        Annotated[
            str,
            DebputyParseHint.target_attribute("sources")
        ]
    ]
    # We allow the user to write  into: foo  in addition to  into: [foo] 
    into: Union[str, List[str]]
# ... into
#      
#        "source": ["foo"]
#        "into": ["pkg"]
#      
class InstallExamplesTargetFormat(TypedDict):
    # Which source files to install (dest-dir is fixed)
    sources: List[str]
    # Which package(s) that should have these files installed.
    into: NotRequired[List[str]]
Without me (as a plugin provider) writing a line of code, I can have debputy rename or "merge" attributes from the manifest form into the normalized form. Obviously, this required me (as the debputy maintainer) to write a lot code so other me and future plugin providers did not have to write it.
High level typing At this point, basic normalization between one mapping to another mapping form worked. But one thing irked me with these install rules. The into was a list of strings when the parser handed them over to me. However, I needed to map them to the actual BinaryPackage (for technical reasons). While I felt I was careful with my manual mapping, I knew this was exactly the kind of case where a busy programmer would skip the "is this a known package name" check and some user would typo their package resulting in an opaque KeyError: foo. Side note: "Some user" was me today and I was super glad to see debputy tell me that I had typoed a package name (I would have been more happy if I had remembered to use debputy check-manifest, so I did not have to wait through the upstream part of the build that happened before debhelper passed control to debputy...) I thought adding this feature would be simple enough. It basically needs two things:
  1. Conversion table where the parser generator can tell that BinaryPackage requires an input of str and a callback to map from str to BinaryPackage. (That is probably lie. I think the conversion table came later, but honestly I do remember and I am not digging into the git history for this one)
  2. At runtime, said callback needed access to the list of known packages, so it could resolve the provided string.
It was not super difficult given the existing infrastructure, but it did take some hours of coding and debugging. Additionally, I added a parse hint to support making the into conditional based on whether it was a single binary package. With this done, you could now write something like:
# Map from
class InstallExamplesManifestFormat(TypedDict):
    # Note that sources here is split into source (str) vs. sources (List[str])
    sources: NotRequired[List[str]]
    source: NotRequired[
        Annotated[
            str,
            DebputyParseHint.target_attribute("sources")
        ]
    ]
    # We allow the user to write  into: foo  in addition to  into: [foo] 
    into: Union[BinaryPackage, List[BinaryPackage]]
# ... into
class InstallExamplesTargetFormat(TypedDict):
    # Which source files to install (dest-dir is fixed)
    sources: List[str]
    # Which package(s) that should have these files installed.
    into: NotRequired[
        Annotated[
            List[BinaryPackage],
            DebputyParseHint.required_when_multi_binary()
        ]
    ]
Code-wise, I still had to check for into being absent and providing a default for that case (that is still true in the current codebase - I will hopefully fix that eventually). But I now had less room for mistakes and a standardized error message when you misspell the package name, which was a plus.
The added side-effect - Introspection A lovely side-effect of all the parsing logic being provided to debputy in a declarative form was that the generated parser snippets had fields containing all expected attributes with their types, which attributes were required, etc. This meant that adding an introspection feature where you can ask debputy "What does an install rule look like?" was quite easy. The code base already knew all of this, so the "hard" part was resolving the input the to concrete rule and then rendering it to the user. I added this feature recently along with the ability to provide online documentation for parser rules. I covered that in more details in my blog post Providing online reference documentation for debputy in case you are interested. :)
Wrapping it up This was a short insight into how debputy parses your input. With this declarative technique:
  • The parser engine handles most of the error reporting meaning users get most of the errors in a standard format without the plugin provider having to spend any effort on it. There will be some effort in more complex cases. But the common cases are done for you.
  • It is easy to provide flexibility to users while avoiding having to write code to normalize the user input into a simplified programmer oriented format.
  • The parser handles mapping from basic types into higher forms for you. These days, we have high level types like FileSystemMode (either an octal or a symbolic mode), different kind of file system matches depending on whether globs should be performed, etc. These types includes their own validation and parsing rules that debputy handles for you.
  • Introspection and support for providing online reference documentation. Also, debputy checks that the provided attribute documentation covers all the attributes in the manifest form. If you add a new attribute, debputy will remind you if you forget to document it as well. :)
In this way everybody wins. Yes, writing this parser generator code was more enjoyable than writing the ad-hoc manual parsers it replaced. :)

Fran ois Marier: Proper Multicast DNS Handling with NetworkManager and systemd-resolved

Using NetworkManager and systemd-resolved together in Debian bookworm does not work out of the box. The first sign of trouble was these constant messages in my logs:
avahi-daemon[pid]: Host name conflict, retrying with hostname-2
Then I realized that CUPS printer discovery didn't work: my network printer could not be found. Since this discovery now relies on Multicast DNS, it would make sense that both problems are related to an incompatibility between NetworkManager and Avahi.

What didn't work The first attempt I made at fixing this was to look for known bugs in Avahi. Neither of the work-arounds I found worked:

What worked The real problem turned out to be the fact that NetworkManager turns on full mDNS support in systemd-resolved which conflicts with the mDNS support in avahi-daemon. You can see this in the output of resolvectl status:
Global
       Protocols: -LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub
Link 2 (enp6s0)
    Current Scopes: DNS mDNS/IPv4 mDNS/IPv6
         Protocols: +DefaultRoute -LLMNR +mDNS -DNSOverTLS
                    DNSSEC=no/unsupported
Current DNS Server: 192.168.1.1
       DNS Servers: 192.168.1.1
        DNS Domain: lan
which includes +mDNS for the main network adapter. I initially thought that I could just uninstall avahi-daemon and rely on the systemd-resolved mDNS stack, but it's not actually compatible with CUPS. The solution was to tell NetworkManager to set mDNS to resolve-only mode in systemd-resolved by adding the following to /etc/NetworkManager/conf.d/mdns.conf:
[connection]
connection.mdns=1
leaving /etc/avahi/avahi-daemon.conf to the default Debian configuration.

Verifying the configuration After rebooting, resolvectl status now shows the following:
Global
       Protocols: -LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
resolv.conf mode: stub
Link 2 (enp6s0)
    Current Scopes: DNS mDNS/IPv4 mDNS/IPv6
         Protocols: +DefaultRoute -LLMNR mDNS=resolve -DNSOverTLS
                    DNSSEC=no/unsupported
Current DNS Server: 192.168.1.1
       DNS Servers: 192.168.1.1
        DNS Domain: lan
Avahi finally sees my printer (called hp in the output below):
$ avahi-browse -at   grep Printer
+ enp6s0 IPv6 hp @ myprintserver   Secure Internet Printer local
+ enp6s0 IPv4 hp @ myprintserver   Secure Internet Printer local
+ enp6s0 IPv6 hp @ myprintserver   Internet Printer        local
+ enp6s0 IPv4 hp @ myprintserver   Internet Printer        local
+ enp6s0 IPv6 hp @ myprintserver   UNIX Printer            local
+ enp6s0 IPv4 hp @ myprintserver   UNIX Printer            local
and so does CUPS:
$ sudo lpinfo --include-schemes dnssd -v
network dnssd://myprintserver%20%40%20hp._ipp._tcp.local/cups?uuid=d46942a2-b730-11ee-b05c-a75251a34287

Firewall rules Since printer discovery in CUPS relies on mDNS, another thing to double-check is that the correct ports are open on the firewall. This is what I have in /etc/network/iptables.up.rules:
# Allow mDNS for local service discovery
-A INPUT -d 100.64.0.0/10 -p udp --dport 5353 -j ACCEPT
-A INPUT -d 192.168.1.0/24 -p udp --dport 5353 -j ACCEPT
and in etc/network/ip6tables.up.rules:
# Allow mDNS for local service discovery
-A INPUT -d ff02::/16 -p udp --dport 5353 -j ACCEPT

19 January 2024

Russell Coker: 2.5Gbit Ethernet

I just decided to upgrade the core of my home network from 1Gbit to 2.5Gbit. I didn t really need to do this, it was only about 5 years ago that I upgrade from 100Mbit to 1Gbit. but it s cheap and seemed interesting. I decided to do it because a 2.5Gbit switch was listed as cheap on Ozbargain Computing [1], that was $40.94 delivered. If you are in Australia and like computers then Ozbargain is a site worth polling, every day there s interesting things at low prices. The seller of the switch is KeeplinkStore [2] who distinguished themselves by phoning me from China to inform me that I had ordered a switch with a UK plug for delivery to Australia and suggesting that I cancel the order and make a new order with an Australian plug. It wouldn t have been a big deal if I had received a UK plug as I ve got a collection of adaptors but it was still nice of them to make it convenient for me. The switch basically does what it s expected to do and has no fan so it s quiet. I got a single port 2.5Gbit PCIe card for $18.77 and a dual port card for $34.07. Those cards are a little expensive when compared to 1Gbit cards but very cheap when compared to the computers they are installed in. These cards use the Realtek RTL8125 chipset and work well. I got a USB-3 2.5Gbit device for $17.43. I deliberately didn t get USB-C because I still use laptops without USB-C and most of the laptops with USB-C only have a single USB-C port which is used for power. I don t plan to stop using my 100Mbit USB ethernet device because most of the time I don t need a lot of speed. But sometimes I do things like testing auto-install on laptops and then having something faster than Gigabit is good. This card worked at 1Gbit speed on a 1Gbit network when used with a system running Debian/Bookworm with kernel 6.1 and worked at 2.5Gbit speed when connected to my LicheePi RISC-V system running Linux 5.10, but it would only do 100Mbit on my laptop running Debian/Unstable with kernel 6.6 (Debian Bug #1061095) [3]. It s a little disappointing but not many people have such hardware so it probably doesn t get a lot of testing. For the moment I plan to just use a 1Gbit USB Ethernet device most of the time and if I really need the speed I ll just use an older kernel. I did some tests with wget and curl to see if I could get decent speeds. When using wget 1.21.3 on Debian/Bookworm I got transfer speeds of 103MB/s and 18.8s of system CPU time out of 23.6s of elapsed time. Curl on Debian/Bookworm did 203MB/s and took 10.7s of system CPU time out of 11.8s elapsed time. The difference is that curl was using 100KB read buffers and a mix of 12K and 4K write buffers while wget was using 8KB read buffers and 4KB write buffers. On Debian/Unstable wget 1.21.4 uses 64K read buffers and a mix of 4K and 60K write buffers and gets a speed of 208MB/s. As an experiment I changed the read buffer size for wget to 256K and that got the speed up to around 220MB/s but it was difficult to measure as the occasional packet loss slowed things down. The pattern of writing 4K and then writing the rest continued, it seemed related to fwrite() buffering. For anyone else who wants to experiment with the code, the wget code is simpler (due to less features) and the package builds a lot faster (due to fewer tests) so that s the one to work on. The client machine for these tests has a E5-2696 v3 CPU, this doesn t compare well to some of the recent AMD CPUs on single-core performance but is still a decently powerful system. Getting good performance at Gigabit speeds on an ARM or RISC-V system is probably going to be a lot harder than getting good performance at 2.5Gbit speeds on this system. In conclusion 2.5Gbit basically works apart from a problem with new kernels and a problem with the old version of wget. I expect that when Debian/Trixie is released (probably mid 2025) things will work well. For good transfer rates use wget version 1.21.4 or newer or use curl. As an aside I use a 1500byte MTU because I have some 100baseT systems on my LAN and the settings regarding TCP acceleration etc are all the defaults.

Reproducible Builds (diffoscope): diffoscope 254 released

The diffoscope maintainers are pleased to announce the release of diffoscope version 254. This version includes the following changes:
[ Chris Lamb ]
* Reflow some code according to black.
[ Seth Michael Larson ]
* Add support for comparing the 'eXtensible ARchive' (.XAR/.PKG) file format.
[ Vagrant Cascadian ]
* Add external tool on GNU Guix for 7z.
You find out more by visiting the project homepage.

18 January 2024

Russell Coker: LicheePi 4A (RISC-V) First Look

I Just bought a LicheePi 4A RISC-V embedded computer (like a RaspberryPi but with a RISC-V CPU) for $322.68 from Aliexpress (the official site for buying LicheePi devices). Here is the Sipheed web page about it and their other recent offerings [1]. I got the version with 16G of RAM and 128G of storage, I probably don t need that much storage (I can use NFS or USB) but 16G of RAM is good for VMs. Here is the Wiki about this board [2]. Configuration When you get one of these devices you should make setting up ssh server your first priority. I found the HDMI output to be very unreliable. The first monitor I tried was a Samsung 4K monitor dating from when 4K was a new thing, the LicheePi initially refused to operate at a resolution higher than 1024*768 but later on switched to 4K resolution when resuming from screen-blank for no apparent reason (and the window manager didn t support this properly). On the Dell 4K monitor I use on my main workstation it sometimes refused to talk to it and occasionally worked. I got it running at 1920*1080 without problems and then switched it to 4K and it lost video sync and never talked to that monitor again. On my Desklab portabable 4K monitor I got it to display in 4K resolution but only the top left 1/4 of the screen displayed. The issues with HDMI monitor support greatly limit the immediate potential for using this as a workstation. It doesn t make it impossible but would be fiddly at best. It s quite likely that a future OS update will fix this. But at the moment it s best used as a server. The LicheePi has a custom Linux distribution based on Ubuntu so you want too put something like the following in /etc/network/interfaces to make it automatically connect to the ethernet when plugged in:
auto end0
iface end0 inet dhcp
Then to get sshd to start you have to run the following commands to generate ssh host keys that aren t zero bytes long:
rm /etc/ssh/ssh_host_*
systemctl restart ssh.service
It appears to have wifi hardware but the OS doesn t recognise it. This isn t a priority for me as I mostly want to use it as a server. Performance For the first test of performance I created a 100MB file from /dev/urandom and then tried compressing it on various systems. With zstd -9 it took 16.893 user seconds on the LicheePi4A, 0.428s on my Thinkpad X1 Carbon Gen5 with a i5-6300U CPU (Debian/Unstable), 1.288s on my E5-2696 v3 workstation (Debian/Bookworm), 0.467s on the E5-2696 v3 running Debian/Unstable, 2.067s on a E3-1271 v3 server, and 7.179s on the E3-1271 v3 system emulating a RISC-V system via QEMU running Debian/Unstable. It s very impressive that the QEMU emulation is fast enough that emulating a different CPU architecture is only 3.5* slower for this test (or maybe 10* slower if it was running Debian/Unstable on the AMD64 code)! The emulated RISC-V is also more than twice as fast as real RISC-V hardware and probably of comparable speed to real RISC-V hardware when running the same versions (and might be slightly slower if running the same version of zstd) which is a tribute to the quality of emulation. One performance issue that most people don t notice is the time taken to negotiate ssh sessions. It s usually not noticed because the common CPUs have got faster at about the same rate as the algorithms for encryption and authentication have become more complex. On my i5-6300U laptop it takes 0m0.384s to run ssh -i ~/.ssh/id_ed25519 localhost id with the below server settings (taken from advice on ssh-audit.com [3] for a secure ssh configuration). On the E3-1271 v3 server it is 0.336s, on the QMU system it is 28.022s, and on the LicheePi it is 0.592s. By this metric the LicheePi is about 80% slower than decent x86 systems and the QEMU emulation of RISC-V is 73* slower than the x86 system it runs on. Does crypto depend on instructions that are difficult to emulate?
HostKey /etc/ssh/ssh_host_ed25519_key
KexAlgorithms -ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha256
MACs -umac-64-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
I haven t yet tested the performance of Ethernet (what routing speed can you get through the 2 gigabit ports?), emmc storage, and USB. At the moment I ve been focused on using RISC-V as a test and development platform. My conclusion is that I m glad I don t plan to compile many kernels or anything large like LibreOffice. But that for typical development that I do it will be quite adequate. The speed of Chromium seems adequate in basic tests, but the video output hasn t worked reliably enough to do advanced tests. Hardware Features Having two Gigabit Ethernet ports, 4 USB-3 ports, and Wifi on board gives some great options for using this as a router. It s disappointing that they didn t go with 2.5Gbit as everyone seems to be doing that nowadays but Gigabit is enough for most things. Having only a single HDMI port and not supporting USB-C docks (the USB-C port appears to be power only) limits what can be done for workstation use and for controlling displays. I know of people using small ARM computers attached to the back of large TVs for advertising purposes and that isn t going to be a great option for this. The CPU and RAM apparently uses a lot of power (which is relative the entire system draws up to 2A at 5V so the CPU would be something below 5W). To get this working a cooling fan has to be stuck to the CPU and RAM chips via a layer of thermal stuff that resembles a fine sheet of blu-tack in both color and stickyness. I am disappointed that there isn t any more solid form of construction, to mount this on a wall or ceiling some extra hardware would be needed to secure this. Also if they just had a really big copper heatsink I think that would be better. 80386 CPUs with similar TDP were able to run without a fan. I wonder how things would work with all USB ports in use. It s expected that a USB port can supply a minimum of 2.5W which means that all the ports could require 10W if they were active. Presumably something significantly less than 5W is available for the USB ports. Other Devices Sipheed has a range of other devices in the works. They currently sell the LicheeCluster4A which support 7 compute modules for a cluster in a box. This has some interesting potential for testing and demonstrating cluster software but you could probably buy an AMD64 system with more compute power for less money. The Lichee Console 4A is a tiny laptop which could be useful for people who like the 7 laptop form factor, unfortunately it only has a 1280*800 display if it had the same resolution display as a typical 7 phone I would have bought one. The next device that appeals to me is the soon to be released Lichee Pad 4A which is a 10.1 tablet with 1920*1200 display, Wifi6, Bluetooth 5.4, and 16G of RAM. It also has 1 USB-C connection, 2*USB-3 sockets, and support for an external card with 2*Gigabit ethernet. It s a tablet as a laptop without keyboard instead of the more common larger phone design model. They are also about to release the LicheePadMax4A which is similar to the other tablet but with a 14 2240*1400 display and which ships with a keyboard to make it essentially a laptop with detachable keyboard. Conclusion At this time I wouldn t recommend that this device be used as a workstation or laptop, although the people who want to do such things will probably do it anyway regardless of my recommendations. I think it will be very useful as a test system for RISC-V development. I have some friends who are interested in this sort of thing and I can give them VMs. It is a bit expensive. The Sipheed web site boasts about the LicheePi4 being faster than the RaspberryPi4, but it s not a lot faster and the RaspberryPi4 is much cheaper ($127 or $129 for one with 8G of RAM). The RaspberryPi4 has two HDMI ports but a limit of 8G of RAM while the LicheePi has up to 16G of RAM and two Gigabit Ethernet ports but only a single HDMI port. It seems that the RaspberryPi4 might win if you want a cheap low power desktop system. At this time I think the reason for this device is testing out RISC-V as an alternative to the AMD64 and ARM64 architectures. An open CPU architecture goes well with free software, but it isn t just people who are into FOSS who are testing such things. I know some corporations are trying out RISC-V as a way of getting other options for embedded systems that don t involve paying monopolists. The Lichee Console 4A is probably a usable tiny laptop if the resolution is sufficient for your needs. As an aside I predict that the tiny laptop or pocket computer segment will take off in the near future. There are some AMD64 systems the size of a phone but thicker that run Windows and go for reasonable prices on AliExpress. Hopefully in the near future this device will have better video drivers and be usable as a small and quiet workstation. I won t rule out the possibility of making this my main workstation in the not too distant future, all it needs is reliable 4K display and the ability to decode 4K video. It s performance for web browsing and as an ssh client seems adequate, and that s what matters for my workstation use. But for the moment it s just for server use.

17 January 2024

Colin Watson: Task management

Now that I m freelancing, I need to actually track my time, which is something I ve had the luxury of not having to do before. That meant something of a rethink of the way I ve been keeping track of my to-do list. Up to now that was a combination of things like the bug lists for the projects I m working on at the moment, whatever task tracking system Canonical was using at the moment (Jira when I left), and a giant flat text file in which I recorded logbook-style notes of what I d done each day plus a few extra notes at the bottom to remind myself of particularly urgent tasks. I could have started manually adding times to each logbook entry, but ugh, let s not. In general, I had the following goals (which were a bit reminiscent of my address book): I didn t do an elaborate evaluation of multiple options, because I m not trying to come up with the best possible solution for a client here. Also, there are a bazillion to-do list trackers out there and if I tried to evaluate them all I d never do anything else. I just wanted something that works well enough for me. Since it came up on Mastodon: a bunch of people swear by Org mode, which I know can do at least some of this sort of thing. However, I don t use Emacs and don t plan to use Emacs. nvim-orgmode does have some support for time tracking, but when I ve tried vim-based versions of Org mode in the past I ve found they haven t really fitted my brain very well. Taskwarrior and Timewarrior One of the other Freexian collaborators mentioned Taskwarrior and Timewarrior, so I had a look at those. The basic idea of Taskwarrior is that you have a task command that tracks each task as a blob of JSON and provides subcommands to let you add, modify, and remove tasks with a minimum of friction. task add adds a task, and you can add metadata like project:Personal (I always make sure every task has a project, for ease of filtering). Just running task shows you a task list sorted by Taskwarrior s idea of urgency, with an ID for each task, and there are various other reports with different filtering and verbosity. task <id> annotate lets you attach more information to a task. task <id> done marks it as done. So far so good, so a redacted version of my to-do list looks like this:
$ task ls
ID A Project     Tags                 Description
17   Freexian                         Add Incus support to autopkgtest [2]
 7   Columbiform                      Figure out Lloyds online banking [1]
 2   Debian                           Fix troffcvt for groff 1.23.0 [1]
11   Personal                         Replace living room curtain rail
Once I got comfortable with it, this was already a big improvement. I haven t bothered to learn all the filtering gadgets yet, but it was easy enough to see that I could do something like task all project:Personal and it d show me both pending and completed tasks in that project, and that all the data was stored in ~/.task - though I have to say that there are enough reporting bells and whistles that I haven t needed to poke around manually. In combination with the regular backups that I do anyway (you do too, right?), this gave me enough confidence to abandon my previous text-file logbook approach. Next was time tracking. Timewarrior integrates with Taskwarrior, albeit in an only semi-packaged way, and it was easy enough to set that up. Now I can do:
$ task 25 start
Starting task 00a9516f 'Write blog post about task tracking'.
Started 1 task.
Note: '"Write blog post about task tracking"' is a new tag.
Tracking Columbiform "Write blog post about task tracking"
  Started 2024-01-10T11:28:38
  Current                  38
  Total               0:00:00
You have more urgent tasks.
Project 'Columbiform' is 25% complete (3 of 4 tasks remaining).
When I stop work on something, I do task active to find the ID, then task <id> stop. Timewarrior does the tedious stopwatch business for me, and I can manually enter times if I forget to start/stop a task. Then the really useful bit: I can do something like timew summary :month <name-of-client> and it tells me how much to bill that client for this month. Perfect. I also started using VIT to simplify the day-to-day flow a little, which means I m normally just using one or two keystrokes rather than typing longer commands. That isn t really necessary from my point of view, but it does save some time. Android integration I left Android integration for a bit later since it wasn t essential. When I got round to it, I have to say that it felt a bit clumsy, but it did eventually work. The first step was to set up a taskserver. Most of the setup procedure was OK, but I wanted to use Let s Encrypt to minimize the amount of messing around with CAs I had to do. Getting this to work involved hitting things with sticks a bit, and there s still a local CA involved for client certificates. What I ended up with was a certbot setup with the webroot authenticator and a custom deploy hook as follows (with cert_name replaced by a DNS name in my house domain):
#! /bin/sh
set -eu
cert_name=taskd.example.org
found=false
for domain in $RENEWED_DOMAINS; do
    case "$domain" in
        $cert_name)
            found=:
            ;;
    esac
done
$found   exit 0
install -m 644 "/etc/letsencrypt/live/$cert_name/fullchain.pem" \
    /var/lib/taskd/pki/fullchain.pem
install -m 640 -g Debian-taskd "/etc/letsencrypt/live/$cert_name/privkey.pem" \
    /var/lib/taskd/pki/privkey.pem
systemctl restart taskd.service
I could then set this in /etc/taskd/config (server.crl.pem and ca.cert.pem were generated using the documented taskserver setup procedure):
server.key=/var/lib/taskd/pki/privkey.pem
server.cert=/var/lib/taskd/pki/fullchain.pem
server.crl=/var/lib/taskd/pki/server.crl.pem
ca.cert=/var/lib/taskd/pki/ca.cert.pem
Then I could set taskd.ca on my laptop to /usr/share/ca-certificates/mozilla/ISRG_Root_X1.crt and otherwise follow the client setup instructions, run task sync init to get things started, and then task sync every so often to sync changes between my laptop and the taskserver. I used TaskWarrior Mobile as the client. I have to say I wouldn t want to use that client as my primary task tracking interface: the setup procedure is clunky even beyond the necessity of copying a client certificate around, it expects you to give it a .taskrc rather than having a proper settings interface for that, and it only seems to let you add a task if you specify a due date for it. It also lacks Timewarrior integration, so I can only really use it when I don t care about time tracking, e.g. personal tasks. But that s really all I need, so it meets my minimum requirements. Next? Considering this is literally the first thing I tried, I have to say I m pretty happy with it. There are a bunch of optional extras I haven t tried yet, but in general it kind of has the vim nature for me: if I need something it s very likely to exist or easy enough to build, but the features I don t use don t get in my way. I wouldn t recommend any of this to somebody who didn t already spend most of their time in a terminal - but I do. I m glad people have gone to all the effort to build this so I didn t have to.

16 January 2024

Matthew Palmer: Pwned Certificates on the Fediverse

As well as the collection and distribution of compromised keys, the pwnedkeys project also matches those pwned keys against issued SSL certificates. I m excited to announce that, as of the beginning of 2024, all matched certificates are now being published on the Fediverse, thanks to the botsin.space Mastodon server. Want to know which sites are susceptible to interception and interference, in (near-)real time? Do you have a burning desire to know who is issuing certificates to people that post their private keys in public? Now you can.

How It Works The process for publishing pwned certs is, roughly, as follows:
  1. All the certificates in Certificate Transparency (CT) logs are hoovered up (using my scrape-ct-log tool, the fastest log scraper in the west!), and the fingerprint of the public key of each certificate is stored in an LMDB datafile.
  2. As new private keys are identified as having been compromised, the fingerprint of that key is checked against all the LMDB files, which map key fingerprints to certificates (actually to CT log entry IDs, from which the certificates themselves are retrieved).
  3. If one or more matches are found, then the certificates using the compromised key are forwarded to the tooter , which publishes them for the world to marvel at.
This makes it sound all very straightforward, and it is in theory. The trick comes in optimising the pipeline so that the five million or so new certificates every day can get indexed on the one slightly middle-aged server I ve got, without getting backlogged.

Why Don t You Just Have the Certificates Revoked? Funny story about that I used to notify CAs of certificates they d issued using compromised keys, which had the effect of requiring them to revoke the associated certificates. However, several CAs disliked having to revoke all those certificates, because it cost them staff time (and hence money) to do so. They went so far as to change their procedures from the standard way of accepting problem reports (emailing a generic attestation of compromise), and instead required CA-specific hoop-jumping to notify them of compromised keys. Since the effectiveness of revocation in the WebPKI is, shall we say, homeopathic at best, I decided I couldn t be bothered to play whack-a-mole with CAs that just wanted to be difficult, and I stopped sending compromised key notifications to CAs. Instead, now I m publishing the details of compromised certificates to everyone, so that users can protect themselves directly should they choose to.

Further Work The astute amongst you may have noticed, in the above How It Works description, a bit of a gap in my scanning coverage. CAs can (and do!) issue certificates for keys that are already compromised, including weak keys that have been known about for a decade or more (1, 2, 3). However, as currently implemented, the pwnedkeys certificate checker does not automatically find such certificates. My plan is to augment the CT scraping / cert processing pipeline to check all incoming certificates against the existing (2M+) set of pwned keys. Though, with over five million new certificates to check every day, it s not necessarily as simple as just hit the pwnedkeys API for every new cert . The poor old API server might not like that very much.

Support My Work If you d like to see this extra matching happen a bit quicker, I ve setup a ko-fi supporters page, where you can support my work on pwnedkeys and the other open source software and projects I work on by buying me a refreshing beverage. I would be very appreciative, and your support lets me know I should do more interesting things with the giant database of compromised keys I ve accumulated.

15 January 2024

Russ Allbery: Review: The Library of Broken Worlds

Review: The Library of Broken Worlds, by Alaya Dawn Johnson
Publisher: Scholastic Press
Copyright: June 2023
ISBN: 1-338-29064-9
Format: Kindle
Pages: 446
The Library of Broken Worlds is a young-adult far-future science fantasy. So far as I can tell, it's stand-alone, although more on that later in the review. Freida is the adopted daughter of Nadi, the Head Librarian, and her greatest wish is to become a librarian herself. When the book opens, she's a teenager in highly competitive training. Freida is low-wetware, without the advanced and expensive enhancements of many of the other students competing for rare and prized librarian positions, which she makes up for by being the most audacious. She doesn't need wetware to commune with the library material gods. If one ventures deep into their tunnels and consumes their crystals, direct physical communion is possible. The library tunnels are Freida's second home, in part because that's where she was born. She was created by the Library, and specifically by Iemaja, the youngest of the material gods. Precisely why is a mystery. To Nadi, Freida is her daughter. To Quinn, Nadi's main political rival within the library, Freida is a thing, a piece of the library, a secondary and possibly rogue AI. A disruptive annoyance. The Library of Broken Worlds is the sort of science fiction where figuring out what is going on is an integral part of the reading experience. It opens with a frame story of an unnamed girl (clearly Freida) waking the god Nameren and identifying herself as designed for deicide. She provokes Nameren's curiosity and offers an Arabian Nights bargain: if he wants to hear her story, he has to refrain from killing her for long enough for her to tell it. As one might expect, the main narrative doesn't catch up to the frame story until the very end of the book. The Library is indeed some type of library that librarians can search for knowledge that isn't available from more mundane sources, but Freida's personal experience of it is almost wholly religious and oracular. The library's material gods are identified as AIs, but good luck making sense of the story through a science fiction frame, even with a healthy allowance for sufficiently advanced technology being indistinguishable from magic. The symbolism and tone is entirely fantasy, and late in the book it becomes clear that whatever the material gods are, they're not simple technological AIs in the vein of, say, Banks's Ship Minds. Also, the Library is not solely a repository of knowledge. It is the keeper of an interstellar peace. The Library was founded after the Great War, to prevent a recurrence. It functions as a sort of legal system and grand tribunal in ways that are never fully explained. As you might expect, that peace is based more on stability than fairness. Five of the players in this far future of humanity are the Awilu, the most advanced society and the first to leave Earth (or Tierra as it's called here); the Mah m, who possess the material war god Nameren of the frame story; the Lunars and Martians, who dominate the Sol system; and the surviving Tierrans, residents of a polluted and struggling planet that is ruthlessly exploited by the Lunars. The problem facing Freida and her friends at the start of the book is a petition brought by a young Tierran against Lunar exploitation of his homeland. His name is Joshua, and Freida is more than half in love with him. Joshua's legal argument involves interpretation of the freedom node of the treaty that ended the Great War, a node that precedent says gives the Lunars the freedom to exploit Tierra, but which Joshua claims has a still-valid originalist meaning granting Tierrans freedom from exploitation. There is, in short, a lot going on in this book, and "never fully explained" is something of a theme. Freida is telling a story to Nameren and only explains things Nameren may not already know. The reader has to puzzle out the rest from the occasional hint. This is made more difficult by the tendency of the material gods to communicate only in visions or guided hallucinations, full of symbolism that the characters only partly explain to the reader. Nonetheless, this did mostly work, at least for me. I started this book very confused, but by about the midpoint it felt like the background was coming together. I'm still not sure I understand the aurochs, baobab, and cicada symbolism that's so central to the framing story, but it's the pleasant sort of stretchy confusion that gives my brain a good workout. I wish Johnson had explained a few more things plainly, particularly near the end of the book, but my remaining level of confusion was within my tolerances. Unfortunately, the ending did not work for me. The first time I read it, I had no idea what it meant. Lots of baffling, symbolic things happened and then the book just stopped. After re-reading the last 10%, I think all the pieces of an ending and a bit of an explanation are there, but it's absurdly abbreviated. This is another book where the author appears to have been finished with the story before I was. This keeps happening to me, so this probably says something more about me than it says about books, but I want books to have an ending. If the characters have fought and suffered through the plot, I want them to have some space to be happy and to see how their sacrifices play out, with more detail than just a few vague promises. If much of the book has been puzzling out the nature of the world, I would like some concrete confirmation of at least some of my guesswork. And if you're going to end the book on radical transformation, I want to see the results of that transformation. Johnson does an excellent job showing how brutal the peace of the powerful can be, and is willing to light more things on fire over the course of this book than most authors would, but then doesn't offer the reader much in the way of payoff. For once, I wish this stand-alone turned out to be a series. I think an additional book could be written in the aftermath of this ending, and I would definitely read that novel. Johnson has me caring deeply about these characters and fascinated by the world background, and I'd happily spend another 450 pages finding out what happens next. But, frustratingly, I think this ending was indeed intended to wrap up the story. I think this book may fall between a few stools. Science fiction readers who want mysterious future worlds to be explained by the end of the book are going to be frustrated by the amount of symbolism, allusion, and poetic description. Literary fantasy readers, who have a higher tolerance for that style, are going to wish for more focused and polished writing. A lot of the story is firmly YA: trying and failing to fit in, developing one's identity, coming into power, relationship drama, great betrayals and regrets, overcoming trauma and abuse, and unraveling lies that adults tell you. But this is definitely not a straight-forward YA plot or world background. It demands a lot from the reader, and while I am confident many teenage readers would rise to that challenge, it seems like an awkward fit for the YA marketing category. About 75% of the way in, I would have told you this book was great and you should read it. The ending was a let-down and I'm still grumpy about it. I still think it's worth your attention if you're in the mood for a sink-or-swim type of reading experience. Just be warned that when the ride ends, I felt unceremoniously dumped on the pavement. Content warnings: Rape, torture, genocide. Rating: 7 out of 10

11 January 2024

Reproducible Builds: Reproducible Builds in December 2023

Welcome to the December 2023 report from the Reproducible Builds project! In these reports we outline the most important things that we have been up to over the past month. As a rather rapid recap, whilst anyone may inspect the source code of free software for malicious flaws, almost all software is distributed to end users as pre-compiled binaries (more).

Reproducible Builds: Increasing the Integrity of Software Supply Chains awarded IEEE Software Best Paper award In February 2022, we announced in these reports that a paper written by Chris Lamb and Stefano Zacchiroli was now available in the March/April 2022 issue of IEEE Software. Titled Reproducible Builds: Increasing the Integrity of Software Supply Chains (PDF). This month, however, IEEE Software announced that this paper has won their Best Paper award for 2022.

Reproducibility to affect package migration policy in Debian In a post summarising the activities of the Debian Release Team at a recent in-person Debian event in Cambridge, UK, Paul Gevers announced a change to the way packages are migrated into the staging area for the next stable Debian release based on its reproducibility status:
The folks from the Reproducibility Project have come a long way since they started working on it 10 years ago, and we believe it s time for the next step in Debian. Several weeks ago, we enabled a migration policy in our migration software that checks for regression in reproducibility. At this moment, that is presented as just for info, but we intend to change that to delays in the not so distant future. We eventually want all packages to be reproducible. To stimulate maintainers to make their packages reproducible now, we ll soon start to apply a bounty [speedup] for reproducible builds, like we ve done with passing autopkgtests for years. We ll reduce the bounty for successful autopkgtests at that moment in time.

Speranza: Usable, privacy-friendly software signing Kelsey Merrill, Karen Sollins, Santiago Torres-Arias and Zachary Newman have developed a new system called Speranza, which is aimed at reassuring software consumers that the product they are getting has not been tampered with and is coming directly from a source they trust. A write-up on TechXplore.com goes into some more details:
What we have done, explains Sollins, is to develop, prove correct, and demonstrate the viability of an approach that allows the [software] maintainers to remain anonymous. Preserving anonymity is obviously important, given that almost everyone software developers included value their confidentiality. This new approach, Sollins adds, simultaneously allows [software] users to have confidence that the maintainers are, in fact, legitimate maintainers and, furthermore, that the code being downloaded is, in fact, the correct code of that maintainer. [ ]
The corresponding paper is published on the arXiv preprint server in various formats, and the announcement has also been covered in MIT News.

Nondeterministic Git bundles Paul Baecher published an interesting blog post on Reproducible git bundles. For those who are not familiar with them, Git bundles are used for the offline transfer of Git objects without an active server sitting on the other side of a network connection. Anyway, Paul wrote about writing a backup system for his entire system, but:
I noticed that a small but fixed subset of [Git] repositories are getting backed up despite having no changes made. That is odd because I would think that repeated bundling of the same repository state should create the exact same bundle. However [it] turns out that for some, repositories bundling is nondeterministic.
Paul goes on to to describe his solution, which involves forcing git to be single threaded makes the output deterministic . The article was also discussed on Hacker News.

Output from libxlst now deterministic libxslt is the XSLT C library developed for the GNOME project, where XSLT itself is an XML language to define transformations for XML files. This month, it was revealed that the result of the generate-id() XSLT function is now deterministic across multiple transformations, fixing many issues with reproducible builds. As the Git commit by Nick Wellnhofer describes:
Rework the generate-id() function to return deterministic values. We use
a simple incrementing counter and store ids in the 'psvi' member of
nodes which was freed up by previous commits. The presence of an id is
indicated by a new "source node" flag.
This fixes long-standing problems with reproducible builds, see
https://bugzilla.gnome.org/show_bug.cgi?id=751621
This also hardens security, as the old implementation leaked the
difference between a heap and a global pointer, see
https://bugs.chromium.org/p/chromium/issues/detail?id=1356211
The old implementation could also generate the same id for dynamically
created nodes which happened to reuse the same memory. Ids for namespace
nodes were completely broken. They now use the id of the parent element
together with the hex-encoded namespace prefix.

Community updates There were made a number of improvements to our website, including Chris Lamb fixing the generate-draft script to not blow up if the input files have been corrupted today or even in the past [ ], Holger Levsen updated the Hamburg 2023 summit to add a link to farewell post [ ] & to add a picture of a Post-It note. [ ], and Pol Dellaiera updated the paragraph about tar and the --clamp-mtime flag [ ]. On our mailing list this month, Bernhard M. Wiedemann posted an interesting summary on some of the reasons why packages are still not reproducible in 2023. 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 processing objdump symbol comment filter inputs as Python byte (and not str) instances [ ] and Vagrant Cascadian extended diffoscope support for GNU Guix [ ] and updated the version in that distribution to version 253 [ ].

Challenges of Producing Software Bill Of Materials for Java Musard Balliu, Benoit Baudry, Sofia Bobadilla, Mathias Ekstedt, Martin Monperrus, Javier Ron, Aman Sharma, Gabriel Skoglund, C sar Soto-Valero and Martin Wittlinger (!) of the KTH Royal Institute of Technology in Sweden, have published an article in which they:
deep-dive into 6 tools and the accuracy of the SBOMs they produce for complex open-source Java projects. Our novel insights reveal some hard challenges regarding the accurate production and usage of software bills of materials.
The paper is available on arXiv.

Debian Non-Maintainer campaign As mentioned in previous reports, the Reproducible Builds team within Debian has been organising a series of online and offline sprints in order to clear the huge backlog of reproducible builds patches submitted by performing so-called NMUs (Non-Maintainer Uploads). During December, Vagrant Cascadian performed a number of such uploads, including: In addition, Holger Levsen performed three no-source-change NMUs in order to address the last packages without .buildinfo files in Debian trixie, specifically lorene (0.0.0~cvs20161116+dfsg-1.1), maria (1.3.5-4.2) and ruby-rinku (1.7.3-2.1).

Reproducibility testing framework The Reproducible Builds project operates a comprehensive testing framework (available at tests.reproducible-builds.org) in order to check packages and other artifacts for reproducibility. In December, a number of changes were made by Holger Levsen:
  • Debian-related changes:
    • Fix matching packages for the [R programming language](https://en.wikipedia.org/wiki/R_(programming_language). [ ][ ][ ]
    • Add a Certbot configuration for the Nginx web server. [ ]
    • Enable debugging for the create-meta-pkgs tool. [ ][ ]
  • Arch Linux-related changes
    • The asp has been deprecated by pkgctl; thanks to dvzrv for the pointer. [ ]
    • Disable the Arch Linux builders for now. [ ]
    • Stop referring to the /trunk branch / subdirectory. [ ]
    • Use --protocol https when cloning repositories using the pkgctl tool. [ ]
  • Misc changes:
    • Install the python3-setuptools and swig packages, which are now needed to build OpenWrt. [ ]
    • Install pkg-config needed to build Coreboot artifacts. [ ]
    • Detect failures due to an issue where the fakeroot tool is implicitly required but not automatically installed. [ ]
    • Detect failures due to rename of the vmlinuz file. [ ]
    • Improve the grammar of an error message. [ ]
    • Document that freebsd-jenkins.debian.net has been updated to FreeBSD 14.0. [ ]
In addition, node maintenance was performed by Holger Levsen [ ] and Vagrant Cascadian [ ].

Upstream 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 appropriate. This month, we wrote a large number of such patches, including:

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:

Matthias Klumpp: Wayland really breaks things Just for now?

This post is in part a response to an aspect of Nate s post Does Wayland really break everything? , but also my reflection on discussing Wayland protocol additions, a unique pleasure that I have been involved with for the past months1.

Some facts Before I start I want to make a few things clear: The Linux desktop will be moving to Wayland2 this is a fact at this point (and has been for a while), sticking to X11 makes no sense for future projects. From reading Wayland protocols and working with it at a much lower level than I ever wanted to, it is also very clear to me that Wayland is an exceptionally well-designed core protocol, and so are the additional extension protocols (xdg-shell & Co.). The modularity of Wayland is great, it gives it incredible flexibility and will for sure turn out to be good for the long-term viability of this project (and also provides a path to correct protocol issues in future, if one is found). In other words: Wayland is an amazing foundation to build on, and a lot of its design decisions make a lot of sense! The shift towards people seeing Linux more as an application developer platform, and taking PipeWire and XDG Portals into account when designing for Wayland is also an amazing development and I love to see this this holistic approach is something I always wanted! Furthermore, I think Wayland removes a lot of functionality that shouldn t exist in a modern compositor and that s a good thing too! Some of X11 s features and design decisions had clear drawbacks that we shouldn t replicate. I highly recommend to read Nate s blog post, it s very good and goes into more detail. And due to all of this, I firmly believe that any advancement in the Wayland space must come from within the project.

But! But! Of course there was a but coming  I think while developing Wayland-as-an-ecosystem we are now entrenched into narrow concepts of how a desktop should work. While discussing Wayland protocol additions, a lot of concepts clash, people from different desktops with different design philosophies debate the merits of those over and over again never reaching any conclusion (just as you will never get an answer out of humans whether sushi or pizza is the clearly superior food, or whether CSD or SSD is better). Some people want to use Wayland as a vehicle to force applications to submit to their desktop s design philosophies, others prefer the smallest and leanest protocol possible, other developers want the most elegant behavior possible. To be clear, I think those are all very valid approaches. But this also creates problems: By switching to Wayland compositors, we are already forcing a lot of porting work onto toolkit developers and application developers. This is annoying, but just work that has to be done. It becomes frustrating though if Wayland provides toolkits with absolutely no way to reach their goal in any reasonable way. For Nate s Photoshop analogy: Of course Linux does not break Photoshop, it is Adobe s responsibility to port it. But what if Linux was missing a crucial syscall that Photoshop needed for proper functionality and Adobe couldn t port it without that? In that case it becomes much less clear on who is to blame for Photoshop not being available. A lot of Wayland protocol work is focused on the environment and design, while applications and work to port them often is considered less. I think this happens because the overlap between application developers and developers of the desktop environments is not necessarily large, and the overlap with people willing to engage with Wayland upstream is even smaller. The combination of Windows developers porting apps to Linux and having involvement with toolkits or Wayland is pretty much nonexistent. So they have less of a voice.

A quick detour through the neuroscience research lab I have been involved with Freedesktop, GNOME and KDE for an incredibly long time now (more than a decade), but my actual job (besides consulting for Purism) is that of a PhD candidate in a neuroscience research lab (working on the morphology of biological neurons and its relation to behavior). I am mostly involved with three research groups in our institute, which is about 35 people. Most of us do all our data analysis on powerful servers which we connect to using RDP (with KDE Plasma as desktop). Since I joined, I have been pushing the envelope a bit to extend Linux usage to data acquisition and regular clients, and to have our data acquisition hardware interface well with it. Linux brings some unique advantages for use in research, besides the obvious one of having every step of your data management platform introspectable with no black boxes left, a goal I value very highly in research (but this would be its own blogpost). In terms of operating system usage though, most systems are still Windows-based. Windows is what companies develop for, and what people use by default and are familiar with. The choice of operating system is very strongly driven by application availability, and WSL being really good makes this somewhat worse, as it removes the need for people to switch to a real Linux system entirely if there is the occasional software requiring it. Yet, we have a lot more Linux users than before, and use it in many places where it makes sense. I also developed a novel data acquisition software that even runs on Linux-only and uses the abilities of the platform to its fullest extent. All of this resulted in me asking existing software and hardware vendors for Linux support a lot more often. Vendor-customer relationship in science is usually pretty good, and vendors do usually want to help out. Same for open source projects, especially if you offer to do Linux porting work for them But overall, the ease of use and availability of required applications and their usability rules supreme. Most people are not technically knowledgeable and just want to get their research done in the best way possible, getting the best results with the least amount of friction.
KDE/Linux usage at a control station for a particle accelerator at Adlershof Technology Park, Germany, for reference (by 25years of KDE)3

Back to the point The point of that story is this: GNOME, KDE, RHEL, Debian or Ubuntu: They all do not matter if the necessary applications are not available for them. And as soon as they are, the easiest-to-use solution wins. There are many facets of easiest : In many cases this is RHEL due to Red Hat support contracts being available, in many other cases it is Ubuntu due to its mindshare and ease of use. KDE Plasma is also frequently seen, as it is perceived a bit easier to onboard Windows users with it (among other benefits). Ultimately, it comes down to applications and 3rd-party support though. Here s a dirty secret: In many cases, porting an application to Linux is not that difficult. The thing that companies (and FLOSS projects too!) struggle with and will calculate the merits of carefully in advance is whether it is worth the support cost as well as continuous QA/testing. Their staff will have to do all of that work, and they could spend that time on other tasks after all. So if they learn that porting to Linux not only means added testing and support, but also means to choose between the legacy X11 display server that allows for 1:1 porting from Windows or the new Wayland compositors that do not support the same features they need, they will quickly consider it not worth the effort at all. I have seen this happen. Of course many apps use a cross-platform toolkit like Qt, which greatly simplifies porting. But this just moves the issue one layer down, as now the toolkit needs to abstract Windows, macOS and Wayland. And Wayland does not contain features to do certain things or does them very differently from e.g. Windows, so toolkits have no way to actually implement the existing functionality in a way that works on all platforms. So in Qt s documentation you will often find texts like works everywhere except for on Wayland compositors or mobile 4. Many missing bits or altered behavior are just papercuts, but those add up. And if users will have a worse experience, this will translate to more support work, or people not wanting to use the software on the respective platform.

What s missing?

Window positioning SDI applications with multiple windows are very popular in the scientific world. For data acquisition (for example with microscopes) we often have one monitor with control elements and one larger one with the recorded image. There is also other configurations where multiple signal modalities are acquired, and the experimenter aligns windows exactly in the way they want and expects the layout to be stored and to be loaded upon reopening the application. Even in the image from Adlershof Technology Park above you can see this style of UI design, at mega-scale. Being able to pop-out elements as windows from a single-window application to move them around freely is another frequently used paradigm, and immensely useful with these complex apps. It is important to note that this is not a legacy design, but in many cases an intentional choice these kinds of apps work incredibly well on larger screens or many screens and are very flexible (you can have any window configuration you want, and switch between them using the (usually) great window management abilities of your desktop). Of course, these apps will work terribly on tablets and small form factors, but that is not the purpose they were designed for and nobody would use them that way. I assumed for sure these features would be implemented at some point, but when it became clear that that would not happen, I created the ext-placement protocol which had some good discussion but was ultimately rejected from the xdg namespace. I then tried another solution based on feedback, which turned out not to work for most apps, and now proposed xdg-placement (v2) in an attempt to maybe still get some protocol done that we can agree on, exploring more options before pushing the existing protocol for inclusion into the ext Wayland protocol namespace. Meanwhile though, we can not port any application that needs this feature, while at the same time we are switching desktops and distributions to Wayland by default.

Window position restoration Similarly, a protocol to save & restore window positions was already proposed in 2018, 6 years ago now, but it has still not been agreed upon, and may not even help multiwindow apps in its current form. The absence of this protocol means that applications can not restore their former window positions, and the user has to move them to their previous place again and again. Meanwhile, toolkits can not adopt these protocols and applications can not use them and can not be ported to Wayland without introducing papercuts.

Window icons Similarly, individual windows can not set their own icons, and not-installed applications can not have an icon at all because there is no desktop-entry file to load the icon from and no icon in the theme for them. You would think this is a niche issue, but for applications that create many windows, providing icons for them so the user can find them is fairly important. Of course it s not the end of the world if every window has the same icon, but it s one of those papercuts that make the software slightly less user-friendly. Even applications with fewer windows like LibrePCB are affected, so much so that they rather run their app through Xwayland for now. I decided to address this after I was working on data analysis of image data in a Python virtualenv, where my code and the Python libraries used created lots of windows all with the default yellow W icon, making it impossible to distinguish them at a glance. This is xdg-toplevel-icon now, but of course it is an uphill battle where the very premise of needing this is questioned. So applications can not use it yet.

Limited window abilities requiring specialized protocols Firefox has a picture-in-picture feature, allowing it to pop out media from a mediaplayer as separate floating window so the user can watch the media while doing other things. On X11 this is easily realized, but on Wayland the restrictions posed on windows necessitate a different solution. The xdg-pip protocol was proposed for this specialized usecase, but it is also not merged yet. So this feature does not work as well on Wayland.

Automated GUI testing / accessibility / automation Automation of GUI tasks is a powerful feature, so is the ability to auto-test GUIs. This is being worked on, with libei and wlheadless-run (and stuff like ydotool exists too), but we re not fully there yet.

Wayland is frustrating for (some) application authors As you see, there is valid applications and valid usecases that can not be ported yet to Wayland with the same feature range they enjoyed on X11, Windows or macOS. So, from an application author s perspective, Wayland does break things quite significantly, because things that worked before can no longer work and Wayland (the whole stack) does not provide any avenue to achieve the same result. Wayland does break screen sharing, global hotkeys, gaming latency (via no tearing ) etc, however for all of these there are solutions available that application authors can port to. And most developers will gladly do that work, especially since the newer APIs are usually a lot better and more robust. But if you give application authors no path forward except use Xwayland and be on emulation as second-class citizen forever , it just results in very frustrated application developers. For some application developers, switching to a Wayland compositor is like buying a canvas from the Linux shop that forces your brush to only draw triangles. But maybe for your avant-garde art, you need to draw a circle. You can approximate one with triangles, but it will never be as good as the artwork of your friends who got their canvases from the Windows or macOS art supply shop and have more freedom to create their art.

Triangles are proven to be the best shape! If you are drawing circles you are creating bad art! Wayland, via its protocol limitations, forces a certain way to build application UX often for the better, but also sometimes to the detriment of users and applications. The protocols are often fairly opinionated, a result of the lessons learned from X11. In any case though, it is the odd one out Windows and macOS do not pose the same limitations (for better or worse!), and the effort to port to Wayland is orders of magnitude bigger, or sometimes in case of the multiwindow UI paradigm impossible to achieve to the same level of polish. Desktop environments of course have a design philosophy that they want to push, and want applications to integrate as much as possible (same as macOS and Windows!). However, there are many applications out there, and pushing a design via protocol limitations will likely just result in fewer apps.

The porting dilemma I spent probably way too much time looking into how to get applications cross-platform and running on Linux, often talking to vendors (FLOSS and proprietary) as well. Wayland limitations aren t the biggest issue by far, but they do start to come come up now, especially in the scientific space with Ubuntu having switched to Wayland by default. For application authors there is often no way to address these issues. Many scientists do not even understand why their Python script that creates some GUIs suddenly behaves weirdly because Qt is now using the Wayland backend on Ubuntu instead of X11. They do not know the difference and also do not want to deal with these details even though they may be programmers as well, the real goal is not to fiddle with the display server, but to get to a scientific result somehow. Another issue is portability layers like Wine which need to run Windows applications as-is on Wayland. Apparently Wine s Wayland driver has some heuristics to make window positioning work (and I am amazed by the work done on this!), but that can only go so far.

A way out? So, how would we actually solve this? Fundamentally, this excessively long blog post boils down to just one essential question: Do we want to force applications to submit to a UX paradigm unconditionally, potentially loosing out on application ports or keeping apps on X11 eternally, or do we want to throw them some rope to get as many applications ported over to Wayland, even through we might sacrifice some protocol purity? I think we really have to answer that to make the discussions on wayland-protocols a lot less grueling. This question can be answered at the wayland-protocols level, but even more so it must be answered by the individual desktops and compositors. If the answer for your environment turns out to be Yes, we want the Wayland protocol to be more opinionated and will not make any compromises for application portability , then your desktop/compositor should just immediately NACK protocols that add something like this and you simply shouldn t engage in the discussion, as you reject the very premise of the new protocol: That it has any merit to exist and is needed in the first place. In this case contributors to Wayland and application authors also know where you stand, and a lot of debate is skipped. Of course, if application authors want to support your environment, you are basically asking them now to rewrite their UI, which they may or may not do. But at least they know what to expect and how to target your environment. If the answer turns out to be We do want some portability , the next question obviously becomes where the line should be drawn and which changes are acceptable and which aren t. We can t blindly copy all X11 behavior, some porting work to Wayland is simply inevitable. Some written rules for that might be nice, but probably more importantly, if you agree fundamentally that there is an issue to be fixed, please engage in the discussions for the respective MRs! We for sure do not want to repeat X11 mistakes, and I am certain that we can implement protocols which provide the required functionality in a way that is a nice compromise in allowing applications a path forward into the Wayland future, while also being as good as possible and improving upon X11. For example, the toplevel-icon proposal is already a lot better than anything X11 ever had. Relaxing ACK requirements for the ext namespace is also a good proposed administrative change, as it allows some compositors to add features they want to support to the shared repository easier, while also not mandating them for others. In my opinion, it would allow for a lot less friction between the two different ideas of how Wayland protocol development should work. Some compositors could move forward and support more protocol extensions, while more restrictive compositors could support less things. Applications can detect supported protocols at launch and change their behavior accordingly (ideally even abstracted by toolkits). You may now say that a lot of apps are ported, so surely this issue can not be that bad. And yes, what Wayland provides today may be enough for 80-90% of all apps. But what I hope the detour into the research lab has done is convince you that this smaller percentage of apps matters. A lot. And that it may be worthwhile to support them. To end on a positive note: When it came to porting concrete apps over to Wayland, the only real showstoppers so far5 were the missing window-positioning and window-position-restore features. I encountered them when porting my own software, and I got the issue as feedback from colleagues and fellow engineers. In second place was UI testing and automation support, the window-icon issue was mentioned twice, but being a cosmetic issue it likely simply hurts people less and they can ignore it easier. What this means is that the majority of apps are already fine, and many others are very, very close! A Wayland future for everyone is within our grasp!  I will also bring my two protocol MRs to their conclusion for sure, because as application developers we need clarity on what the platform (either all desktops or even just a few) supports and will or will not support in future. And the only way to get something good done is by contribution and friendly discussion.

Footnotes
  1. Apologies for the clickbait-y title it comes with the subject
  2. When I talk about Wayland I mean the combined set of display server protocols and accepted protocol extensions, unless otherwise clarified.
  3. I would have picked a picture from our lab, but that would have needed permission first
  4. Qt has awesome platform issues pages, like for macOS and Linux/X11 which help with porting efforts, but Qt doesn t even list Linux/Wayland as supported platform. There is some information though, like window geometry peculiarities, which aren t particularly helpful when porting (but still essential to know).
  5. Besides issues with Nvidia hardware CUDA for simulations and machine-learning is pretty much everywhere, so Nvidia cards are common, which causes trouble on Wayland still. It is improving though.

10 January 2024

Dirk Eddelbuettel: BH 1.84.0-1 on CRAN: New Upstream

Boost Boost is a very large and comprehensive set of (peer-reviewed) libraries for the C++ programming language, containing well over one hundred individual libraries. The BH package provides a sizeable subset of header-only libraries for (easier, no linking required) use by R. It is fairly widely used: the (partial) CRAN mirror logs (aggregated from the cloud mirrors) show over 35.7 million package downloads. Version 1.84.0 of Boost was released in December following the regular Boost release schedule of April, August and December releases. As the commits and changelog show, we packaged it almost immediately and started testing following our annual update cycle which strives to balance being close enough to upstream and not stressing CRAN and the user base too much. The reverse depends check revealed five packages requiring changes or adjustments which is a pretty good outcome given the over three hundred direct reverse dependencies. So we opened issue #100 to coordinate the issue over the winter break during which CRAN also closes (just as we did in previous years). Our sincere thanks to the two packages that already updated before, and to the one that updated today within hours (!!) of the BH uploaded it needed. There are very few actual changes. We honoured one request (in issue #97) to add Boost QVM bringing quarternion support to R. No other new changes needed to be made. A number of changes I have to make each time in BH, and it is worth mentioning them. Because CRAN cares about backwards compatibility and the ability to be used on minimal or older systems, we still adjust the filenames of a few files to fit a jurassic constraints of just over a 100 characters per filepath present in some long-outdated versions of tar. Not a big deal. We also, and that is more controversial, silence a number of #pragma diagnostic messages for g++ and clang++ because CRAN insists on it. I have no choice in that matter. One warning we suppressed last year, but no longer do, concerns the C++14 standard that some Boost libraries now default to. Packages setting C++11 explicitly will likely get a note from CRAN changing this; in most cases that should be trivial to remove as we only had to opt into (then) newer standards under old compilers. These days newer defaults help; R itself now defaults to C++17.

Changes in version 1.84.0-0 (2024-01-09)

Via my CRANberries, there is a diffstat report relative to the previous release. Comments and suggestions about BH are welcome via the issue tracker at the GitHub repo. If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Dirk Eddelbuettel: Rcpp 1.0.12 on CRAN: New Maintenance / Update Release

rcpp logo The Rcpp Core Team is once again thrilled to announce a new release 1.0.12 of the Rcpp package. It arrived on CRAN early today, and has since been uploaded to Debian as well. Windows and macOS builds should appear at CRAN in the next few days, as will builds in different Linux distribution and of course at r2u should catch up tomorrow. The release was uploaded yesterday, and run its reverse dependencies overnight. Rcpp always gets flagged nomatter what because the grandfathered .Call(symbol) but we had not single change to worse among over 2700 reverse dependencies! This release continues with the six-months January-July cycle started with release 1.0.5 in July 2020. As a reminder, we do of course make interim snapshot dev or rc releases available via the Rcpp drat repo and strongly encourage their use and testing I run my systems with these versions which tend to work just as well, and are also fully tested against all reverse-dependencies. Rcpp has long established itself as the most popular way of enhancing R with C or C++ code. Right now, 2791 packages on CRAN depend on Rcpp for making analytical code go faster and further, along with 254 in BioConductor. On CRAN, 13.8% of all packages depend (directly) on Rcpp, and 59.9% of all compiled packages do. From the cloud mirror of CRAN (which is but a subset of all CRAN downloads), Rcpp has been downloaded 78.1 million times. The two published papers (also included in the package as preprint vignettes) have, respectively, 1766 (JSS, 2011) and 292 (TAS, 2018) citations, while the the book (Springer useR!, 2013) has another 617. This release is incremental as usual, generally preserving existing capabilities faithfully while smoothing our corners and / or extending slightly, sometimes in response to changing and tightened demands from CRAN or R standards. The full list below details all changes, their respective PRs and, if applicable, issue tickets. Big thanks from all of us to all contributors!

Changes in Rcpp release version 1.0.12 (2024-01-08)
  • Changes in Rcpp API:
    • Missing header includes as spotted by some recent tools were added in two places (Michael Chirico in #1272 closing #1271).
    • Casts to avoid integer overflow in matrix row/col selections have neem added (Aaron Lun #1281).
    • Three print format correction uncovered by R-devel were applied with thanks to Tomas Kalibera (Dirk in #1285).
    • Correct a print format correction in the RcppExports glue code (Dirk in #1288 fixing #1287).
    • The upcoming OBJSXP addition to R 4.4.0 is supported in the type2name mapper (Dirk and I aki in #1293).
  • Changes in Rcpp Attributes:
    • Generated interface code from base R that fails under LTO is now corrected (I aki in #1274 fixing a StackOverflow issue).
  • Changes in Rcpp Documentation:
    • The caption for third figure in the introductory vignette has been corrected (Dirk in #1277 fixing #1276).
    • A small formatting issue was correct in an Rd file as noticed by R-devel (Dirk in #1282).
    • The Rcpp FAQ vignette has been updated (Dirk in #1284).
    • The Rcpp.bib file has been refreshed to current package versions.
  • Changes in Rcpp Deployment:
    • The RcppExports file for an included test package has been updated (Dirk in #1289).

Thanks to my CRANberries, you can also look at a diff to the previous release Questions, comments etc should go to the rcpp-devel mailing list off the R-Forge page. Bugs reports are welcome at the GitHub issue tracker as well (where one can also search among open or closed issues). If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

9 January 2024

Louis-Philippe V ronneau: 2023 A Musical Retrospective

I ended 2022 with a musical retrospective and very much enjoyed writing that blog post. As such, I have decided to do the same for 2023! From now on, this will probably be an annual thing :) Albums In 2023, I added 73 new albums to my collection nearly 2 albums every three weeks! I listed them below in the order in which I acquired them. I purchased most of these albums when I could and borrowed the rest at libraries. If you want to browse though, I added links to the album covers pointing either to websites where you can buy them or to Discogs when digital copies weren't available. Once again this year, it seems that Punk (mostly O !) and Metal dominate my list, mostly fueled by Angry Metal Guy and the amazing Montr al Skinhead/Punk concert scene. Concerts A trend I started in 2022 was to go to as many concerts of artists I like as possible. I'm happy to report I went to around 80% more concerts in 2023 than in 2022! Looking back at my list, April was quite a busy month... Here are the concerts I went to in 2023: Although metalfinder continues to work as intended, I'm very glad to have discovered the Montr al underground scene has departed from Facebook/Instagram and adopted en masse Gancio, a FOSS community agenda that supports ActivityPub. Our local instance, askapunk.net is pretty much all I could ask for :) That's it for 2023!

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