Search Results: "ron"

30 September 2020

Chris Lamb: Free software activities in September 2020

Here is my monthly update covering what I have been doing in the free software world during September 2020 (previous month):

Reproducible Builds One of the original promises of open source software is that distributed peer review and transparency of process results in enhanced end-user security. However, whilst anyone may inspect the source code of free and open source software for malicious flaws, almost all software today is distributed as pre-compiled binaries. This allows nefarious third-parties to compromise systems by injecting malicious code into ostensibly secure software during the various compilation and distribution processes. The motivation behind the Reproducible Builds effort is to ensure no flaws have been introduced during this compilation process by promising identical results are always generated from a given source, thus allowing multiple third-parties to come to a consensus on whether a build was compromised. The project is proud to be a member project of the Software Freedom Conservancy. Conservancy acts as a corporate umbrella allowing projects to operate as non-profit initiatives without managing their own corporate structure. If you like the work of the Conservancy or the Reproducible Builds project, please consider becoming an official supporter. This month, I:

diffoscope I made the following changes to diffoscope, including preparing and uploading versions 159 and 160 to Debian:

Debian Lintian For Lintian, the static analysis tool for Debian packages, I uploaded versions 2.93.0, 2.94.0, 2.95.0 & 2.96.0 (not counting uploads to the backports repositories), as well as: Debian LTS This month I've worked 18 hours on Debian Long Term Support (LTS) and 12 hours on its sister Extended LTS project. You can find out more about the project via the following video:
Uploads Bugs filed

29 September 2020

Mike Gabriel: UBports: Packaging of Lomiri Operating Environment for Debian (part 03)

Before and during FOSDEM 2020, I agreed with the people (developers, supporters, managers) of the UBports Foundation to package the Unity8 Operating Environment for Debian. Since 27th Feb 2020, Unity8 has now become Lomiri. Recent Uploads to Debian related to Lomiri Over the past 4 months I worked on the following bits and pieces regarding Lomiri in Debian: The next two big projects / packages ahead are lomiri-ui-toolkit and qtmir. Credits Many big thanks go to Marius and Dalton for their work on the UBports project and being always available for questions, feedback, etc. Thanks to Ratchanan Srirattanamet for providing some of his time for debugging some non-thread safe unit tests (currently unsure, what package we actually looked at...). Thanks for Florian Leeber for being my point of contact for topcis regarding my cooperation with the UBports Foundation. Previous Posts about my Debian UBports Team Efforts

Norbert Preining: Performance with Intel i218/i219 NIC

I always had the feeling that my server, hosted by Hetzner, somehow has a slow internet connection. Then, I did put it on the distance between Finland and Japan, and didn t care too much. Until yesterday my server stopped reacting to pings/ssh, and needed a hard reset. It turned out that the server was running fine, only that the ethernet card did hang. Hetzner support answered promptly and directed me to this web page, which described a change in the kernel concerning fragmentation offloading, and suggested the following configuration to regain connection speed: 
ethtool -K <interface> tso off gso off
And to my surprise, this simple thing did wonder, and the connection speed improved dramatically, even from Japan (something like factor 10 in large rsync transfers). I have added this incantation to system cron tab and run it every hour, just to be sure that even after a reboot it is fine. If you have bad connection speed with this kind of ethernet card, give it a try.

28 September 2020

Vincent Bernat: Syncing RIPE, ARIN and APNIC objects with a custom Ansible module

Internet is split into five regional Internet registry: AFRINIC, ARIN, APNIC, LACNIC and RIPE. Each RIR maintains an Internet Routing Registry. An IRR allows one to publish information about the routing of Internet number resources.1 Operators use this to determine the owner of an IP address and to construct and maintain routing filters. To ensure your routes are widely accepted, it is important to keep the prefixes you announce up-to-date in an IRR. There are two common tools to query this database: whois and bgpq4. The first one allows you to do a query with the WHOIS protocol: 
$ whois -BrG 2a0a:e805:400::/40
[ ]
inet6num:       2a0a:e805:400::/40
netname:        FR-BLADE-CUSTOMERS-DE
country:        DE
geoloc:         50.1109 8.6821
admin-c:        BN2763-RIPE
tech-c:         BN2763-RIPE
status:         ASSIGNED
mnt-by:         fr-blade-1-mnt
remarks:        synced with cmdb
created:        2020-05-19T08:04:58Z
last-modified:  2020-05-19T08:04:58Z
source:         RIPE
route6:         2a0a:e805:400::/40
descr:          Blade IPv6 - AMS1
origin:         AS64476
mnt-by:         fr-blade-1-mnt
remarks:        synced with cmdb
created:        2019-10-01T08:19:34Z
last-modified:  2020-05-19T08:05:00Z
source:         RIPE
The second one allows you to build route filters using the information contained in the IRR database: 
$ bgpq4 -6 -S RIPE -b AS64476
NN = [
    2a0a:e805::/40,
    2a0a:e805:100::/40,
    2a0a:e805:300::/40,
    2a0a:e805:400::/40,
    2a0a:e805:500::/40
];
There is no module available on Ansible Galaxy to manage these objects. Each IRR has different ways of being updated. Some RIRs propose an API but some don t. If we restrict ourselves to RIPE, ARIN and APNIC, the only common method to update objects is email updates, authenticated with a password or a GPG signature.2 Let s write a custom Ansible module for this purpose!

Notice I recommend that you read Writing a custom Ansible module as an introduction, as well as Syncing MySQL tables for a more instructive example.

Code The module takes a list of RPSL objects to synchronize and returns the body of an email update if a change is needed: 
- name: prepare RIPE objects
  irr_sync:
    irr: RIPE
    mntner: fr-blade-1-mnt
    source: whois-ripe.txt
  register: irr

Prerequisites The source file should be a set of objects to sync using the RPSL language. This would be the same content you would send manually by email. All objects should be managed by the same maintainer, which is also provided as a parameter. Signing and sending the result is not the responsibility of this module. You need two additional tasks for this purpose: 
- name: sign RIPE objects
  shell:
    cmd: gpg --batch --user noc@example.com --clearsign
    stdin: "  irr.objects  "
  register: signed
  check_mode: false
  changed_when: false
- name: update RIPE objects by email
  mail:
    subject: "NEW: update for RIPE"
    from: noc@example.com
    to: "auto-dbm@ripe.net"
    cc: noc@example.com
    host: smtp.example.com
    port: 25
    charset: us-ascii
    body: "  signed.stdout  "
You also need to authorize the PGP keys used to sign the updates by creating a key-cert object and adding it as a valid authentication method for the corresponding mntner object: 
key-cert:  PGPKEY-A791AAAB
certif:    -----BEGIN PGP PUBLIC KEY BLOCK-----
certif:    
certif:    mQGNBF8TLY8BDADEwP3a6/vRhEERBIaPUAFnr23zKCNt5YhWRZyt50mKq1RmQBBY
[ ]
certif:    -----END PGP PUBLIC KEY BLOCK-----
mnt-by:    fr-blade-1-mnt
source:    RIPE
mntner:    fr-blade-1-mnt
[ ]
auth:      PGPKEY-A791AAAB
mnt-by:    fr-blade-1-mnt
source:    RIPE

Module definition Starting from the skeleton described in the previous article, we define the module: 
module_args = dict(
    irr=dict(type='str', required=True),
    mntner=dict(type='str', required=True),
    source=dict(type='path', required=True),
)
result = dict(
    changed=False,
)
module = AnsibleModule(
    argument_spec=module_args,
    supports_check_mode=True
)

Getting existing objects To grab existing objects, we use the whois command to retrieve all the objects from the provided maintainer. 
# Per-IRR variations:
# - whois server
whois =  
    'ARIN': 'rr.arin.net',
    'RIPE': 'whois.ripe.net',
    'APNIC': 'whois.apnic.net'
 
# - whois options
options =  
    'ARIN': ['-r'],
    'RIPE': ['-BrG'],
    'APNIC': ['-BrG']
 
# - objects excluded from synchronization
excluded = ["domain"]
if irr == "ARIN":
    # ARIN does not return these objects
    excluded.extend([
        "key-cert",
        "mntner",
    ])
# Grab existing objects
args = ["-h", whois[irr],
        "-s", irr,
        *options[irr],
        "-i", "mnt-by",
        module.params['mntner']]
proc = subprocess.run("whois", *args, capture_output=True)
if proc.returncode != 0:
    raise AnsibleError(
        f"unable to query whois:  args ")
output = proc.stdout.decode('ascii')
got = extract(output, excluded)
The first part of the code setup some IRR-specific constants: the server to query, the options to provide to the whois command and the objects to exclude from synchronization. The second part invokes the whois command, requesting all objects whose mnt-by field is the provided maintainer. Here is an example of output: 
$ whois -h whois.ripe.net -s RIPE -BrG -i mnt-by fr-blade-1-mnt
[ ]
inet6num:       2a0a:e805:300::/40
netname:        FR-BLADE-CUSTOMERS-FR
country:        FR
geoloc:         48.8566 2.3522
admin-c:        BN2763-RIPE
tech-c:         BN2763-RIPE
status:         ASSIGNED
mnt-by:         fr-blade-1-mnt
remarks:        synced with cmdb
created:        2020-05-19T08:04:59Z
last-modified:  2020-05-19T08:04:59Z
source:         RIPE
[ ]
route6:         2a0a:e805:300::/40
descr:          Blade IPv6 - PA1
origin:         AS64476
mnt-by:         fr-blade-1-mnt
remarks:        synced with cmdb
created:        2019-10-01T08:19:34Z
last-modified:  2020-05-19T08:05:00Z
source:         RIPE
[ ]
The result is passed to the extract() function. It parses and normalizes the results into a dictionary mapping object names to objects. We store the result in the got variable. 
def extract(raw, excluded):
    """Extract objects."""
    # First step, remove comments and unwanted lines
    objects = "\n".join([obj
                         for obj in raw.split("\n")
                         if not obj.startswith((
                                 "#",
                                 "%",
                         ))])
    # Second step, split objects
    objects = [RPSLObject(obj.strip())
               for obj in re.split(r"\n\n+", objects)
               if obj.strip()
               and not obj.startswith(
                   tuple(f" x :" for x in excluded))]
    # Last step, put objects in a dict
    objects =  repr(obj): obj
               for obj in objects 
    return objects
RPSLObject() is a class enabling normalization and comparison of objects. Look at the module code for more details. 
>>> output="""
... inet6num:       2a0a:e805:300::/40
... [ ]
... """
>>> pprint( k: str(v) for k,v in extract(output, excluded=[]) )
 '<Object:inet6num:2a0a:e805:300::/40>':
   'inet6num:       2a0a:e805:300::/40\n'
   'netname:        FR-BLADE-CUSTOMERS-FR\n'
   'country:        FR\n'
   'geoloc:         48.8566 2.3522\n'
   'admin-c:        BN2763-RIPE\n'
   'tech-c:         BN2763-RIPE\n'
   'status:         ASSIGNED\n'
   'mnt-by:         fr-blade-1-mnt\n'
   'remarks:        synced with cmdb\n'
   'source:         RIPE',
 '<Object:route6:2a0a:e805:300::/40>':
   'route6:         2a0a:e805:300::/40\n'
   'descr:          Blade IPv6 - PA1\n'
   'origin:         AS64476\n'
   'mnt-by:         fr-blade-1-mnt\n'
   'remarks:        synced with cmdb\n'
   'source:         RIPE'

Comparing with wanted objects Let s build the wanted dictionary using the same structure, thanks to the extract() function we can use verbatim: 
with open(module.params['source']) as f:
    source = f.read()
wanted = extract(source, excluded)
The next step is to compare got and wanted to build the diff object: 
if got != wanted:
    result['changed'] = True
    if module._diff:
        result['diff'] = [
            dict(before_header=k,
                 after_header=k,
                 before=str(got.get(k, "")),
                 after=str(wanted.get(k, "")))
            for k in set((*wanted.keys(), *got.keys()))
            if k not in wanted or k not in got or wanted[k] != got[k]]

Returning updates The module does not have a side effect. If there is a difference, we return the updates to send by email. We choose to include all wanted objects in the updates (contained in the source variable) and let the IRR ignore unmodified objects. We also append the objects to be deleted by adding a delete: attribute to each them them. 
# We send all source objects and deleted objects.
deleted_mark = f" 'delete:':16 deleted by CMDB"
deleted = "\n\n".join([f" got[k].raw \n deleted_mark "
                       for k in got
                       if k not in wanted])
result['objects'] = f" source \n\n deleted "
module.exit_json(**result)
The complete code is available on GitHub. The module supports both --diff and --check flags. It does not return anything if no change is detected. It can work with APNIC, RIPE and ARIN. It is not perfect: it may not detect some changes,3 it is not able to modify objects not owned by the provided maintainer4 and some attributes cannot be modified, requiring to manually delete and recreate the updated object.5 However, this module should automate 95% of your needs.
  1. Other IRRs exist without being attached to a RIR. The most notable one is RADb.
  2. ARIN is phasing out this method in favor of IRR-online. RIPE has an API available, but email updates are still supported and not planned to be deprecated. APNIC plans to expose an API.
  3. For ARIN, we cannot query key-cert and mntner objects and therefore we cannot detect changes in them. It is also not possible to detect changes to the auth mechanisms of a mntner object.
  4. APNIC do not assign top-level objects to the maintainer associated with the owner.
  5. Changing the status of an inetnum object requires deleting and recreating the object.

27 September 2020

Enrico Zini: Coup d' tat in recent Italian history

Italy during the cold war has always been in too strategic a position, and with too strong a left wing movement, not to get the CIA involved. Here are a few stories of coup d' tat and other kinds of efforts to manipulate Italian politics:

Joachim Breitner: Learn Haskell on CodeWorld writing Sokoban

Two years ago, I held the CIS194 minicourse on Haskell at the University of Pennsylvania. In that installment of the course, I changed the first four weeks to teach the basics of Haskell using the online Haskell environment CodeWorld, and lead the students towards implementing the game Sokoban. As it is customary for CIS194, I put my lecture notes and exercises online, and this has been used as a learning resources by people from all over the world. But since I have left the University of Pennsylvania, I lost the ability to update the text, and as the CodeWorld API has evolved, some of the examples and exercises no longer work. Some recent complains about that, in bug reports against CodeWorld and in unrealistically flattering tweets ( Shame, this was the best Haskell course ever!!! ) motivated me to extract that material and turn it into an updated stand-alone tutorial that I can host myself. So if you feel like learning Haskell without worrying about local installation, and while creating a reasonably fun game, head over to https://haskell-via-sokoban.nomeata.de/ and get started! Improvements can now also be contributed at https://github.com/nomeata/haskell-via-sokoban. Credits go to Brent Yorgey, Richard Eisenberg and Noam Zilberstein, who held the previous installments of the course, and Chris Smith for creating the CodeWorld environment.

26 September 2020

Dirk Eddelbuettel: #30: Easy, Reliable, Fast and Portable Linux and macOS Continuous Integration

Welcome to the 30th post in the rarified R recommendation resources series or R4 for short. The last post introduced BSPM. In the four weeks since, we have worked some more on BSPM to bring it to the point where it is ready for use with continuous integration. Building on this, it is now used inside the run.sh script that driven our CI use for many years (via the r-travis repo). Which we actually use right now on three different platforms: All three use the exact same script facilitating this, and run a matrix over Linux and macOS. You read this right: one CI setup that is portable and which you can take to your CI provider of choice. No lock-in or tie-in. Use what works, change at will. Or run on all three if you like burning extra cycles. This is already used by handful of my repos as well as by at least two repos of friends also deploying r-travis. How does it work? In a nutshell we are There are several customizations that are possible via environment variables We find this setup compelling. The scheme is simple: there really is just one shell script behind it which can also be downloaded and altered. The scheme is also portable as we can (as shown) rotate between CI provides. The scheme is also more flexible: in case of debugging needs one can simply run the script on a local Docker or VM instance. Lastly, the scheme moves away from single points of failure or breakage. Currently the script uses only BSPM as I had the hunch that it would a) work and b) be compelling. Adding support for RSPM would be equally easy, but I have no immediate need to do so. Adding BioConductor installation may be next. That is easy when BioConductor uses r-release; it may be little more challenging under r-devel to but it should work too. Stay tuned. In the meantime, if the above sounds compelling, give run.sh from r-travis a go! If you like this or other open-source work I do, you can now sponsor me at GitHub. For the first year, GitHub will match your contributions.

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

25 September 2020

Colin Watson: Porting Launchpad to Python 3: progress report

Launchpad still requires Python 2, which in 2020 is a bit of a problem. Unlike a lot of the rest of 2020, though, there s good reason to be optimistic about progress. I ve been porting Python 2 code to Python 3 on and off for a long time, from back when I was on the Ubuntu Foundations team and maintaining things like the Ubiquity installer. When I moved to Launchpad in 2015 it was certainly on my mind that this was a large body of code still stuck on Python 2. One option would have been to just accept that and leave it as it is, maybe doing more backporting work over time as support for Python 2 fades away. I ve long been of the opinion that this would doom Launchpad to being unmaintainable in the long run, and since I genuinely love working on Launchpad - I find it an incredibly rewarding project - this wasn t something I was willing to accept. We re already seeing some of our important dependencies dropping support for Python 2, which is perfectly reasonable on their terms but which is starting to become a genuine obstacle to delivering important features when we need new features from newer versions of those dependencies. It also looks as though it may be difficult for us to run on Ubuntu 20.04 LTS (we re currently on 16.04, with an upgrade to 18.04 in progress) as long as we still require Python 2, since we have some system dependencies that 20.04 no longer provides. And then there are exciting new features like type hints and async/await that we d like to be able to use. However, until last year there were so many blockers that even considering a port was barely conceivable. What changed in 2019 was sorting out a trifecta of core dependencies. We ported our database layer, Storm. We upgraded to modern versions of our Zope Toolkit dependencies (after contributing various fixes upstream, including some substantial changes to Zope s test runner that we d carried as local patches for some years). And we ported our Bazaar code hosting infrastructure to Breezy. With all that in place, a port seemed more of a realistic possibility. Still, even with this, it was never going to be a matter of just following some standard porting advice and calling it good. Launchpad has almost a million lines of Python code in its main git tree, and around 250 dependencies of which a number are quite Launchpad-specific. In a project that size, not only is following standard porting advice an extremely time-consuming task in its own right, but just about every strange corner case is going to show up somewhere. (Did you know that StringIO.StringIO(None) and io.StringIO(None) do different things even after you account for the native string vs. Unicode text difference? How about the behaviour of .union() on a subclass of frozenset?) Launchpad s test suite is fortunately extremely thorough, but even just starting up the test suite involves importing most of the data model code, so before you can start taking advantage of it you have to make a large fraction of the codebase be at least syntactically-correct Python 3 code and use only modules that exist in Python 3 while still working in Python 2; in a project this size that turns out to be a large effort on its own, and can be quite risky in places. Canonical s product engineering teams work on a six-month cycle, but it just isn t possible to cram this sort of thing into six months unless you do literally nothing else, and please can we put all feature development on hold while we run to stand still is a pretty tough sell to even the most understanding management. Fortunately, we ve been able to grow the Launchpad team in the last year or so, and so it s been possible to put Python 3 on our roadmap on the understanding that we aren t going to get all the way there in one cycle, while still being able to do other substantial feature development work as well. So, with all that preamble, what have we done this cycle? We ve taken a two-pronged approach. From one end, we identified 147 classes that needed to be ported away from some compatibility code in our database layer that was substantially less friendly to Python 3: we ve ported 38 of those, so there s clearly a fair bit more to do, but we were able to distribute this work out among the team quite effectively. From the other end, it was clear that it would be very inefficient to do general porting work when any attempt to even run the test suite would run straight into the same crashes in the same order, so I set myself a target of getting the test suite to start up, and started hacking on an enormous git branch that I never expected to try to land directly: instead, I felt free to commit just about anything that looked reasonable and moved things forward even if it was very rough, and every so often went back to tidy things up and cherry-pick individual commits into a form that included some kind of explanation and passed existing tests so that I could propose them for review. This strategy has been dramatically more successful than anything I ve tried before at this scale. So far this cycle, considering only Launchpad s main git tree, we ve landed 137 Python-3-relevant merge proposals for a total of 39552 lines of git diff output, keeping our existing tests passing along the way and deploying incrementally to production. We have about 27000 more lines of patch at varying degrees of quality to tidy up and merge. Our main development branch is only perhaps 10 or 20 more patches away from the test suite being able to start up, at which point we ll be able to get a buildbot running so that multiple developers can work on this much more easily and see the effect of their work. With the full unlanded patch stack, about 75% of the test suite passes on Python 3! This still leaves a long tail of several thousand tests to figure out and fix, but it s a much more incrementally-tractable kind of problem than where we started. Finally: the funniest (to me) bug I ve encountered in this effort was the one I encountered in the test runner and fixed in zopefoundation/zope.testrunner#106: IDs of failing tests were written to a pipe, so if you have a test suite that s large enough and broken enough then eventually that pipe would reach its capacity and your test runner would just give up and hang. Pretty annoying when it meant an overnight test run didn t give useful results, but also eloquent commentary of sorts.

23 September 2020

Vincent Fourmond: Tutorial: analyze Km data of CODHs

This is the first post of a series in which we will provide the readers with simple tutorial approaches to reproduce the data analysis of some of our published papers. All our data analysis is performed using QSoas. Today, we will show you how to analyze the experiments we used to characterize the behaviour of an enzyme, the Nickel-Iron CO dehydrogenase IV from Carboxytothermus hydrogenoformans. The experiments we analyze here are described in much more details in the original publication, Domnik et al, Angewandte Chemie, 2017. The only things you need to know for now are the following: This means that we expect a response of the type: $$i(t) = \frac i_m 1 + \frac K_m [\mathrm CO ](t) $$ in which $$[\mathrm CO ](t) = \begin cases 0, & \text for t < t_0 \\ C_0 \exp \frac t_0 - t \tau , & \text for t\geq t_0 %> \end cases $$ To begin this tutorial, first download the files from the github repository (direct links: data, parameter file and ruby script). Start QSoas, go to the directory where you saved the files, load the data file, and remove spikes in the data using the following commands: 
QSoas> cd
QSoas> l Km-CODH-IV.dat
QSoas> R
First fitThen, to fit the above equation to the data, the simplest is to take advantage of the time-dependent parameters features of QSoas. Run simply: 
QSoas> fit-arb im/(1+km/s) /with=s:1,exp
This simply launches the fit interface to fit the exact equations above. The im/(1+km/s) is simply the translation of the Michaelis-Menten equation above, and the /with=s:1,exp specifies that s is the result of the sum of 1 exponential like for the definition of above. Then, load the Km-CODH-IV.params parameter files (using the "Parameters.../Load from file" action at the bottom, or the Ctrl+L keyboard shortcut). Your window should now look like this:
To fit the data, just hit the "Fit" button ! (or Ctrl+F). Including an offset The fit is not bad, but not perfect. In particular, it is easy to see why: the current predicted by the fit goes to 0 at large times, but the actual current is below 0. We need therefore to include an offset to take this into consideration. Close the fit window, and re-run a fit, but now with this command: 
QSoas> fit-arb im/(1+km/s)+io /with=s:1,exp
Notice the +io bit that corresponds to the addition of an offset current. Load again the base parameters, run the fit again... Your fit window show now look like:
See how the offset current is now much better taken into account. Let's talk a bit more about the parameters: Taking into account mass-transport limitations However, the fit is still unsatisfactory: the predicted curve fails to reproduce the curvature at the beginning and at the end of the decrease. This is due to issues linked to mass-transport limitations, which are discussed in details in Merrouch et al, Electrochimica Acta, 2017. In short, what you need to do is to close the fit window again, load the transport.rb Ruby file that contains the definition of the itrpt function, and re-launch the fit window using: 
QSoas> ruby-run transport.rb
QSoas> fit-arb itrprt(s,km,nFAm,nFAmu)+io /with=s:1,exp
Load again the parameter file... but this time you'll have to play a bit more with the starting parameters for QSoas to find the right values when you fit. Here are some tips: A successful fit should look like this:
Here you are ! I hope you enjoyed analyzing our data, and that it will help you analyze yours ! Feel free to comment and ask for clarifications.

About QSoasQSoas is a powerful open source data analysis program that focuses on flexibility and powerful fitting capacities. It is released under the GNU General Public License. It is described in Fourmond, Anal. Chem., 2016, 88 (10), pp 5050 5052. Current version is 2.2. You can download its source code or buy precompiled versions for MacOS and Windows there.

22 September 2020

Russ Allbery: Review: Unconquerable Sun

Review: Unconquerable Sun, by Kate Elliott
Series: Sun Chronicles #1
Publisher: Tor
Copyright: 2020
ISBN: 1-250-19725-2
Format: Kindle
Pages: 526
Sun is the daughter and heir of the mercurial Queen-Marshal Eirene, ruler of the Republic of Chaonia. Chaonia, thanks to Eirene and her ancestors, has carved out a fiercely independent position between the Yele League and the Phene Empire. Sun's father, Prince Jo o, is one of Eirene's three consorts, all chosen for political alliances to shore up that fragile position. Jo o is Gatoi, a civilization of feared fighters and supposed barbarians from outside Chaonia who normally ally with the Phene, which complicates Sun's position as heir. Sun attempts to compensate for that by winning battles for the Republic, following in the martial footsteps of her mother. The publisher's summary of this book is not great (I'm a huge fan of Princess Leia, but that is... not the analogy that comes to mind), so let me try to help. This is gender-swapped Alexander the Great in space. However, it is gender-swapped Alexander the Great in space with her Companions, which means the DNA of this novel is half space opera and half heist story (without, to be clear, an actual heist, although there are some heist-like maneuvers). It's also worth mentioning that Sun, like Alexander, is not heterosexual. The other critical thing to know before reading, mostly because it will get you through the rather painful start, is that the most interesting viewpoint character in this book is not Sun, the Alexander analogue. It's Persephone, who isn't introduced until chapter seven. Significant disclaimer up front: I got a reasonably typical US grade school history of Alexander the Great, which means I was taught that he succeeded his father, conquered a whole swath of the middle of the Eurasian land mass at a very young age, and then died and left his empire to his four generals who promptly divided it into four uninteresting empires that no one's ever heard of, and that's why Rome is more important than Greece. (I put in that last bit to troll one specific person.) I am therefore not the person to judge the parallels between this story and known history, or to notice any damage done to Greek pride, or to pick up on elements that might cause someone with a better grasp of that history to break out in hives. I did enough research to know that one scene in this book is lifted directly out of Alexander's life, but I'm not sure how closely the other parallels track. Yele is probably southern Greece and Phene is probably Persia, but I'm not certain even of that, and some of the details don't line up. If I had to hazard a guess, I'd say that Elliott has probably mangled history sufficiently to make it clear that this isn't intended to be a retelling, but if the historical parallels are likely to bother you, you may want to do more research before reading. What I can say is that the space opera setup, while a bit stock, has all the necessary elements to make me happy. Unconquerable Sun is firmly in the "lost Earth" tradition: The Argosy fleet fled the now-mythical Celestial Empire and founded a new starfaring civilization without any contact with their original home. Eventually, they invented (or discovered; the characters don't know) the beacons, which allow for instantaneous travel between specific systems without the long (but still faster-than-light) journeys of the knnu drive. More recently, the beacon network has partly collapsed, cutting off the characters' known world from the civilization that was responsible for the beacons and guarded their secrets. It's a fun space opera history with lots of lost knowledge to reference and possibly discover, and with plot-enabling military choke points at the surviving beacons that link multiple worlds. This is all background to the story, which is the ongoing war between Chaonia and the Phene Empire mixed with cutthroat political maneuvering between the great houses of the Chaonian Republic. This is where the heist aspects come in. Each house sends one representative to join the household of the Queen-Marshal and (more to the point for this story) another to join her heir. Sun has encouraged the individual and divergent talents of her Companions and their cee-cees (an unfortunate term that I suspect is short for Companion's Companion) and forged them into a good working team. A team that's about to be disrupted by the maneuverings of a rival house and the introduction of a new team member whom no one wants. A problem with writing tactical geniuses is that they often aren't good viewpoint characters. Sun's tight third-person chapters, which is a little less than half the book, advance the plot and provide analysis of the interpersonal dynamics of the characters, but aren't the strength of the story. That lies with the interwoven first-person sections that follow Persephone, an altogether more interesting character. Persephone is the scion of the house that is Sun's chief rival, but she has no interest in being part of that house or its maneuverings. When the story opens, she's a cadet in a military academy for recruits from the commoners, having run away from home, hidden her identity, and won a position through the open entrance exams. She of course doesn't stay there; her past catches up with her and she gets assigned to Sun, to a great deal of mutual suspicion. She also is assigned an impeccably dressed and stunningly beautiful cee-cee, Tiana, who has her own secrets and who was my favorite character in the book. Somewhat unusually for the space opera tradition, this is a book that knows that common people exist and have interesting lives. It's primarily focused on the ruling houses, but that focus is not exclusive and the rulers do not have a monopoly on competence. Elliott also avoids narrowing the political field too far; the Gatoi are separate from the three rival powers, and there are other groups with traditions older than the Chaonian Republic and their own agendas. Sun and her Companions are following a couple of political threads, but there is clearly more going on in this world than that single plot. This is exactly the kind of story I think of when I think space opera. It's not doing anything that original or groundbreaking, and it's not going to make any of my lists of great literature, but it's a fun romp with satisfyingly layered bits of lore, a large-scale setting with lots of plot potential, and (once we get through the confusing and somewhat tedious process of introducing rather too many characters in short succession) some great interpersonal dynamics. It's the kind of book in which the characters are in the middle of decisive military action in an interstellar war and are also near-teenagers competing for ratings in an ad hoc reality TV show, primarily as an excuse to create tactical distractions for Sun's latest scheme. The writing is okay but not great, and the first few chapters have some serious infodumping problems, but I thoroughly enjoyed the whole book and will pre-order the sequel. One Amazon review complained that Unconquerable Sun is not a space opera like Hyperion or Use of Weapons. That is entirely true, but if that's your standard for space opera, the world may be a disappointing place. This is a solid entry in a subgenre I love, with some great characters, sarcasm, competence porn, plenty of pages to keep turning, a few twists, and the promise of more to come. Recommended. Followed by the not-yet-published Furious Heaven. Rating: 7 out of 10

21 September 2020

Kees Cook: security things in Linux v5.7

Previously: v5.6 Linux v5.7 was released at the end of May. Here s my summary of various security things that caught my attention: arm64 kernel pointer authentication
While the ARMv8.3 CPU Pointer Authentication (PAC) feature landed for userspace already, Kristina Martsenko has now landed PAC support in kernel mode. The current implementation uses PACIASP which protects the saved stack pointer, similar to the existing CONFIG_STACKPROTECTOR feature, only faster. This also paves the way to sign and check pointers stored in the heap, as a way to defeat function pointer overwrites in those memory regions too. Since the behavior is different from the traditional stack protector, Amit Daniel Kachhap added an LKDTM test for PAC as well. BPF LSM
The kernel s Linux Security Module (LSM) API provide a way to write security modules that have traditionally implemented various Mandatory Access Control (MAC) systems like SELinux, AppArmor, etc. The LSM hooks are numerous and no one LSM uses them all, as some hooks are much more specialized (like those used by IMA, Yama, LoadPin, etc). There was not, however, any way to externally attach to these hooks (not even through a regular loadable kernel module) nor build fully dynamic security policy, until KP Singh landed the API for building LSM policy using BPF. With this, it is possible (for a privileged process) to write kernel LSM hooks in BPF, allowing for totally custom security policy (and reporting). execve() deadlock refactoring
There have been a number of long-standing races in the kernel s process launching code where ptrace could deadlock. Fixing these has been attempted several times over the last many years, but Eric W. Biederman and Ernd Edlinger decided to dive in, and successfully landed the a series of refactorings, splitting up the problematic locking and refactoring their uses to remove the deadlocks. While he was at it, Eric also extended the exec_id counter to 64 bits to avoid the possibility of the counter wrapping and allowing an attacker to send arbitrary signals to processes they normally shouldn t be able to. slub freelist obfuscation improvements
After Silvio Cesare observed some weaknesses in the implementation of CONFIG_SLAB_FREELIST_HARDENED s freelist pointer content obfuscation, I improved their bit diffusion, which makes attacks require significantly more memory content exposures to defeat the obfuscation. As part of the conversation, Vitaly Nikolenko pointed out that the freelist pointer s location made it relatively easy to target too (for either disclosures or overwrites), so I moved it away from the edge of the slab, making it harder to reach through small-sized overflows (which usually target the freelist pointer). As it turns out, there were a few assumptions in the kernel about the location of the freelist pointer, which had to also get cleaned up. RISCV page table dumping
Following v5.6 s generic page table dumping work, Zong Li landed the RISCV page dumping code. This means it s much easier to examine the kernel s page table layout when running a debug kernel (built with PTDUMP_DEBUGFS), visible in /sys/kernel/debug/kernel_page_tables. array index bounds checking
This is a pretty large area of work that touches a lot of overlapping elements (and history) in the Linux kernel. The short version is: C is bad at noticing when it uses an array index beyond the bounds of the declared array, and we need to fix that. For example, don t do this: 
int foo[5];
...
foo[8] = bar;
The long version gets complicated by the evolution of flexible array structure members, so we ll pause for a moment and skim the surface of this topic. While things like CONFIG_FORTIFY_SOURCE try to catch these kinds of cases in the memcpy() and strcpy() family of functions, it doesn t catch it in open-coded array indexing, as seen in the code above. GCC has a warning (-Warray-bounds) for these cases, but it was disabled by Linus because of all the false positives seen due to fake flexible array members. Before flexible arrays were standardized, GNU C supported zero sized array members. And before that, C code would use a 1-element array. These were all designed so that some structure could be the header in front of some data blob that could be addressable through the last structure member: 
/* 1-element array */
struct foo  
    ...
    char contents[1];
 ;
/* GNU C extension: 0-element array */
struct foo  
    ...
    char contents[0];
 ;
/* C standard: flexible array */
struct foo  
    ...
    char contents[];
 ;
instance = kmalloc(sizeof(struct foo) + content_size);
Converting all the zero- and one-element array members to flexible arrays is one of Gustavo A. R. Silva s goals, and hundreds of these changes started landing. Once fixed, -Warray-bounds can be re-enabled. Much more detail can be found in the kernel s deprecation docs. However, that will only catch the visible at compile time cases. For runtime checking, the Undefined Behavior Sanitizer has an option for adding runtime array bounds checking for catching things like this where the compiler cannot perform a static analysis of the index values: 
int foo[5];
...
for (i = 0; i < some_argument; i++)  
    ...
    foo[i] = bar;
    ...
It was, however, not separate (via kernel Kconfig) until Elena Petrova and I split it out into CONFIG_UBSAN_BOUNDS, which is fast enough for production kernel use. With this enabled, it's now possible to instrument the kernel to catch these conditions, which seem to come up with some regularity in Wi-Fi and Bluetooth drivers for some reason. Since UBSAN (and the other Sanitizers) only WARN() by default, system owners need to set panic_on_warn=1 too if they want to defend against attacks targeting these kinds of flaws. Because of this, and to avoid bloating the kernel image with all the warning messages, I introduced CONFIG_UBSAN_TRAP which effectively turns these conditions into a BUG() without needing additional sysctl settings. Fixing "additive" snprintf() usage
A common idiom in C for building up strings is to use sprintf()'s return value to increment a pointer into a string, and build a string with more sprintf() calls: 
/* safe if strlen(foo) + 1 < sizeof(string) */
wrote  = sprintf(string, "Foo: %s\n", foo);
/* overflows if strlen(foo) + strlen(bar) > sizeof(string) */
wrote += sprintf(string + wrote, "Bar: %s\n", bar);
/* writing way beyond the end of "string" now ... */
wrote += sprintf(string + wrote, "Baz: %s\n", baz);
The risk is that if these calls eventually walk off the end of the string buffer, it will start writing into other memory and create some bad situations. Switching these to snprintf() does not, however, make anything safer, since snprintf() returns how much it would have written: 
/* safe, assuming available <= sizeof(string), and for this example
 * assume strlen(foo) < sizeof(string) */
wrote  = snprintf(string, available, "Foo: %s\n", foo);
/* if (strlen(bar) > available - wrote), this is still safe since the
 * write into "string" will be truncated, but now "wrote" has been
 * incremented by how much snprintf() *would* have written, so "wrote"
 * is now larger than "available". */
wrote += snprintf(string + wrote, available - wrote, "Bar: %s\n", bar);
/* string + wrote is beyond the end of string, and availabe - wrote wraps
 * around to a giant positive value, making the write effectively 
 * unbounded. */
wrote += snprintf(string + wrote, available - wrote, "Baz: %s\n", baz);
So while the first overflowing call would be safe, the next one would be targeting beyond the end of the array and the size calculation will have wrapped around to a giant limit. Replacing this idiom with scnprintf() solves the issue because it only reports what was actually written. To this end, Takashi Iwai has been landing a bunch scnprintf() fixes. That's it for now! Let me know if there is anything else you think I should mention here. Next up: Linux v5.8.

2020, Kees Cook. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 License.
CC BY-SA 4.0

Jonathan McDowell: Mainline Linux on the MikroTik RB3011

I upgraded my home internet connection to fibre (FTTP) last October. I m still on an 80M/20M service, so it s no faster than my old VDSL FTTC connection was, and as a result for a long time I continued to use my HomeHub 5A running OpenWRT. However the FTTP ONT meant I was using up an additional ethernet port on the router, and I was already short, so I ended up with a GigE switch in use as well. Also my wifi is handled by a UniFi, which takes its power via Power-over-Ethernet. That mean I had a router, a switch and a PoE injector all in close proximity. I wanted to reduce the number of devices, and ideally upgrade to something that could scale once I decide to upgrade my FTTP service speed. Looking around I found the MikroTik RB3011UiAS-RM, which is a rack mountable device with 10 GigE ports (plus an SFP slot) and a dual core Qualcomm IPQ8064 ARM powering it. There s 1G RAM and 128MB NAND flash, as well as a USB3 port. It also has PoE support. On paper it seemed like an ideal device. I wasn t particularly interested in running RouterOS on it (the provided software), but that s based on Linux and there was some work going on within OpenWRT to add support, so it seemed like a worthwhile platform to experiment with (what, you expected this to be about me buying an off the shelf device and using it with only the supplied software?). As an added bonus a friend said he had one he wasn t using, and was happy to sell it to me for a bargain price. RB3011 router in use I did try out RouterOS to start with, but I didn t find it particularly compelling. I m comfortable configuring firewalling and routing at a Linux command line, and I run some additional services on the router like my MQTT broker, and mqtt-arp, my wifi device presence monitor. I could move things around such that they ran on the house server, but I consider them core services and as a result am happier with them on the router. The first step was to get something booting on the router. Luckily it has an RJ45 serial console port on the back, and a reasonably featured bootloader that can manage to boot via tftp over the network. It wants an ELF binary rather than a plain kernel, but Sergey Sergeev had done the hard work of getting u-boot working for the IPQ8064, which mean I could just build normal u-boot images to try out. Linux upstream already had basic support for a lot of the pieces I was interested in. There s a slight fudge around AUTO_ZRELADDR because the network coprocessors want a chunk of memory at the start of RAM, but there s ongoing discussions about how to handle this cleanly that I m hopeful will eventually mean I can drop that hack. Serial, ethernet, the QCA8337 switches (2 sets of 5 ports, tied to different GigE devices on the processor) and the internal NOR all had drivers, so it was a matter of crafting an appropriate DTB to get them working. That left niggles. First, the second switch is hooked up via SGMII. It turned out the IPQ806x stmmac driver didn t initialise the clocks in this mode correctly, and neither did the qca8k switch driver. So I need to fix up both of those (Sergey had handled the stmmac driver, so I just had to clean up and submit his patch). Next it turned out the driver for talking to the Qualcomm firmware (SCM) had been updated in a way that broke the old method needed on the IPQ8064. Some git archaeology figured that one out and provided a solution. Ansuel Smith helpfully provided the DWC3 PHY driver for the USB port. That got me to the point I could put a Debian armhf image onto a USB stick and mount that as root, which made debugging much easier. At this point I started to play with configuring up the device to actually act as a router. I make use of a number of VLANs on my home network, so I wanted to make sure I could support those. Turned out the stmmac driver wasn t happy reconfiguring its MTU because the IPQ8064 driver doesn t configure the FIFO sizes. I found what seem to be the correct values and plumbed them in. Then the qca8k driver only supported port bridging. I wanted the ability to have a trunk port to connect to the upstairs switch, while also having ports that only had a single VLAN for local devices. And I wanted the switch to handle this rather than requiring the CPU to bridge the traffic. Thankfully it s easy to find a copy of the QCA8337 datasheet and the kernel Distributed Switch Architecture is pretty flexible, so I was able to implement the necessary support. I stuck with Debian on the USB stick for actually putting the device into production. It makes it easier to fix things up if necessary, and the USB stick allows for a full Debian install which would be tricky on the 128M of internal NAND. That means I can use things like nftables for my firewalling, and use the standard Debian packages for things like collectd and mosquitto. Plus for debug I can fire up things like tcpdump or tshark. Which ended up being useful because when I put the device into production I started having weird IPv6 issues that turned out to be a lack of proper Ethernet multicast filter support in the IPQ806x ethernet device. The driver would try and setup the multicast filter for the IPv6 NDP related packets, but it wouldn t actually work. The fix was to fall back to just receiving all multicast packets - this is what the vendor driver does. Most of this work will be present once the 5.9 kernel is released - the basics are already in 5.8. Currently not queued up that I can think of are the following: Overall I consider the device a success, and it s been entertaining getting it working properly. I m running a mostly mainline kernel, it s handling my house traffic without breaking a sweat, and the fact it s running Debian makes it nice and easy to throw more things on it as I desire. However it turned out the RB3011 isn t as perfect device as I d hoped. The PoE support is passive, and the UniFi wants 802.1af. So I was going to end up with 2 devices. As it happened I picked up a cheap D-Link DGS-1210-10P switch, which provides the PoE support as well as some additional switch ports. Plus it runs Linux, so more on that later

Russ Allbery: Review: Lower Ed

Review: Lower Ed, by Tressie McMillan Cottom
Publisher: The New Press
Copyright: 2017
Printing: 2018
ISBN: 1-62097-472-X
Format: Kindle
Pages: 217
Lower Ed (subtitled The Troubling Rise of For-Profit Colleges in the New Economy) is the first book by sociologist Tressie McMillan Cottom. (I previously reviewed her second book, the excellent essay collection Thick.) It is a deep look at the sociology of for-profit higher education in the United States based on interviews with students and executives, analysis of Wall Street filings, tests of the admissions process, and her own personal experiences working for two of the schools. One of the questions that McMillan Cottom tries to answer is why students choose to enroll in these institutions, particularly the newer type of institution funded by federal student loans and notorious for being more expensive and less valuable than non-profit colleges and universities. I was hesitant to read this book because I find for-profit schools depressing. I grew up with the ubiquitous commercials, watched the backlash develop, and have a strongly negative impression of the industry, partly influenced by having worked in traditional non-profit higher education for two decades. The prevailing opinion in my social group is that they're a con job. I was half-expecting a reinforcement of that opinion by example, and I don't like reading infuriating stories about people being defrauded. I need not have worried. This is not that sort of book (nor, in retrospect, do I think McMillan Cottom would approach a topic from that angle). Sociology is broader than reporting. Lower Ed positions for-profit colleges within a larger social structure of education, credentialing, and changes in workplace expectations; takes a deep look at why they are attractive to their students; and humanizes and complicates the motives and incentives of everyone involved, including administrators and employees of for-profit colleges as well as the students. McMillan Cottom does of course talk about the profit motive and the deceptions surrounding that, but the context is less that of fraud that people are unable to see through and more a balancing of the drawbacks of a set of poor choices embedded in institutional failures. One of my metrics for a good non-fiction book is whether it introduces me to a new idea that changes how I analyze the world. Lower Ed does that twice. The first idea is the view of higher education through the lens of risk shifting. It used to be common for employers to hire people without prior job-specific training and do the training in-house, possibly through an apprenticeship structure. More notably, once one was employed by a particular company, the company routinely arranged or provided ongoing training. This went hand-in-hand with a workplace culture of long tenure, internal promotion, attempts to avoid layoffs, and some degree of mutual loyalty. Companies expected to invest significantly in an employee over their career and thus also had an incentive to retain that employee rather than train someone for a competitor. However, from a purely financial perspective, this is a risk and an inefficiency, similar to the risk of carrying a large inventory of parts and components. Companies have responded to investor-driven focus on profits and efficiency by reducing overhead and shifting risk. This leads to the lean supply chain, where no one pays for parts to sit around in warehouses and companies aren't caught with large stockpiles of now-useless components, but which is more sensitive to any disruption (such as from a global pandemic). And, for employment, it leads to a desire to hire pre-trained workers, retain only enough workers to do the current amount of work, and replace them with new workers who already have appropriate training rather than retrain them. The effect of the corporate decision to only hire pre-trained employees is to shift the risk and expense of training from the company to the prospective employee. The individual has to seek out training at their own expense in the hope (not guarantee) that at the conclusion of that training they will get or retain a job. People therefore turn to higher education to both provide that training and to help them decide what type of training will eventually be valuable. This has a long history with certain professional fields (doctors and lawyers, for example), but the requirements for completing training in those fields are relatively clear (a professional license to practice) and the compensation reflects the risk. What's new is the shift of training risk to the individual in more mundane jobs, without any corresponding increase in compensation. This, McMillan Cottom explains, is the background for the growth in demand for higher education in general and the the type of education offered by for-profit colleges in particular. Workers who in previous eras would be trained by their employers are now responsible for their own training. That training is no longer judged by the standards of a specific workplace, but is instead evaluated by a hiring process that expects constant job-shifting. This leads to increased demand by both workers and employers for credentials: some simple-to-check certificate of completion of training that says that this person has the skills to immediately start doing some job. It also leads to a demand for more flexible class hours, since the student is now often someone older with a job and a family to balance. Their ongoing training used to be considered a cost of business and happen during their work hours; now it is something they have to fit around the contours of their life because their employer has shifted that risk to them. The risk-shifting frame makes sense of the "investment" language so common in for-profit education. In this job economy, education as investment is not a weird metaphor for the classic benefits of a liberal arts education: broadened perspective, deeper grounding in philosophy and ethics, or heightened aesthetic appreciation. It's an investment in the literal financial sense; it is money that you spend now in order to get a financial benefit (a job) in the future. People have to invest in their own training because employers are no longer doing so, but still require the outcome of that investment. And, worse, it's primarily a station-keeping investment. Rather than an optional expenditure that could reap greater benefits later, it's a mandatory expenditure to prevent, at best, stagnation in a job paying poverty wages, and at worst the disaster of unemployment. This explains renewed demand for higher education, but why for-profit colleges? We know they cost more and have a worse reputation (and therefore their credentials have less value) than traditional non-profit colleges. Flexible hours and class scheduling explains some of this but not all of it. That leads to the second perspective-shifting idea I got from Lower Ed: for-profit colleges are very good at what they focus time and resources on, and they focus on enrolling students. It is hard to enroll in a university! More precisely, enrolling in a university requires bureaucracy navigation skills, and those skills are class-coded. The people who need them the most are the least likely to have them. Universities do not reach out to you, nor do they guide you through the process. You have to go to them and discover how to apply, something that is often made harder by the confusing state of many university web sites. The language and process is opaque unless other people in your family have experience with universities and can explain it. There might be someone you can reach on the phone to ask questions, but they're highly unlikely to proactively guide you through the remaining steps. It's your responsibility to understand deadlines, timing, and sequence of operations, and if you miss any of the steps (due to, for example, the overscheduled life of someone in need of better education for better job prospects), the penalty in time and sometimes money can be substantial. And admission is just the start; navigating financial aid, which most students will need, is an order of magnitude more daunting. Community colleges are somewhat easier (and certainly cheaper) than universities, but still have similar obstacles (and often even worse web sites). It's easy for people like me, who have long professional expertise with bureaucracies, family experience with higher education, and a support network of people to nag me about deadlines, to underestimate this. But the application experience at a for-profit college is entirely different in ways far more profound than I had realized. McMillan Cottom documents this in detail from her own experience working for two different for-profit colleges and from an experiment where she indicated interest in multiple for-profit colleges and then stopped responding before signing admission paperwork. A for-profit college is fully invested in helping a student both apply and get financial aid, devotes someone to helping them through that process, does not expect them to understand how to navigate bureaucracies or decipher forms on their own, does not punish unexpected delays or missed appointments, and goes to considerable lengths to try to keep anyone from falling out of the process before they are enrolled. They do not expect their students to already have the skills that one learns from working in white-collar jobs or from being surrounded by people who do. They provide the kind of support that an educational institution should provide to people who, by definition, don't understand something and need to learn. Reading about this was infuriating. Obviously, this effort to help people enroll is largely for predatory reasons. For-profit schools make their money off federal loans and they don't get that money unless they can get someone to enroll and fill out financial paperwork (and to some extent keep them enrolled), so admissions is their cash cow and they act accordingly. But that's not why I found it infuriating; that's just predictable capitalism. What I think is inexcusable is that nothing they do is that difficult. We could being doing the same thing for prospective community college students but have made the societal choice not to. We believe that education is valuable, we constantly advocate that people get more job training and higher education, and yet we demand prospective students navigate an unnecessarily baroque and confusing application process with very little help, and then stereotype and blame them for failing to do so. This admission support is not a question of resources. For-profit colleges are funded almost entirely by federally-guaranteed student loans. We are paying them to help people apply. It is, in McMillan Cottom's term, a negative social insurance program. Rather than buffering people against the negative effects of risk-shifting of employers by helping them into the least-expensive and most-effective training programs (non-profit community colleges and universities), we are spending tax dollars to enrich the shareholders of for-profit colleges while underfunding the alternatives. We are choosing to create a gap that routes government support to the institution that provides worse training at higher cost but is very good at helping people apply. It's as if the unemployment system required one to use payday lenders to get one's unemployment check. There is more in this book I want to talk about, but this review is already long enough. Suffice it to say that McMillan Cottom's analysis does not stop with market forces and the admission process, and the parts of her analysis that touch on my own personal experience as someone with a somewhat unusual college path ring very true. Speaking as a former community college student, the discussion of class credit transfer policies and the way that institutional prestige gatekeeping and the desire to push back against low-quality instruction becomes a trap that keeps students in the for-profit system deserves another review this length. So do the implications of risk-shifting and credentialism on the morality of "cheating" on schoolwork. As one would expect from the author of the essay "Thick" about bringing context to sociology, Lower Ed is personal and grounded. McMillan Cottom doesn't shy away from including her own experiences and being explicit about her sources and research. This is backed up by one of the best methodological notes sections I've seen in a book. One of the things I love about McMillan Cottom's writing is that it's solidly academic, not in the sense of being opaque or full of jargon (the text can be a bit dense, but I rarely found it hard to follow), but in the sense of being clear about the sources of knowledge and her methods of extrapolation and analysis. She brings her receipts in a refreshingly concrete way. I do have a few caveats. First, I had trouble following a structure and line of reasoning through the whole book. Each individual point is meticulously argued and supported, but they are not always organized into a clear progression or framework. That made Lower Ed feel at times like a collection of high-quality but somewhat unrelated observations about credentials, higher education, for-profit colleges, their student populations, their business models, and their relationships with non-profit schools. Second, there are some related topics that McMillan Cottom touches on but doesn't expand sufficiently for me to be certain I understood them. One of the big ones is credentialism. This is apparently a hot topic in sociology and is obviously important to this book, but it's referenced somewhat glancingly and was not satisfyingly defined (at least for me). There are a few similar places where I almost but didn't quite follow a line of reasoning because the book structure didn't lay enough foundation. Caveats aside, though, this was meaty, thought-provoking, and eye-opening, and I'm very glad that I read it. This is a topic that I care more about than most people, but if you have watched for-profit colleges with distaste but without deep understanding, I highly recommend Lower Ed. Rating: 8 out of 10

19 September 2020

Vincent Bernat: Keepalived and unicast over multiple interfaces

Keepalived is a Linux implementation of VRRP. The usual role of VRRP is to share a virtual IP across a set of routers. For each VRRP instance, a leader is elected and gets to serve the IP address, ensuring the high availability of the attached service. Keepalived can also be used for a generic leader election, thanks to its ability to use scripts for healthchecking and run commands on state change. A simple configuration looks like this: 
vrrp_instance gateway1  
  state BACKUP          #  
  interface eth0        #  
  virtual_router_id 12  #  
  priority 101          #  
  virtual_ipaddress  
    2001:db8:ff/64
The state keyword in instructs Keepalived to not take the leader role when starting. Otherwise, incoming nodes create a temporary disruption by taking over the IP address until the election settles. The interface keyword in defines the interface for sending and receiving VRRP packets. It is also the default interface to configure the virtual IP address. The virtual_router_id directive in is common to all nodes sharing the virtual IP. The priority keyword in helps choosing which router will be elected as leader. If you need more information around Keepalived, be sure to check the documentation. VRRP design is tied to Ethernet networks and requires a multicast-enabled network for communication between nodes. In some environments, notably public clouds, multicast is unavailable. In this case, Keepalived can send VRRP packets using unicast: 
vrrp_instance gateway1  
  state BACKUP
  interface eth0
  virtual_router_id 12
  priority 101
  unicast_peer  
    2001:db8::11
    2001:db8::12
   
  virtual_ipaddress  
    2001:db8:ff/64 dev lo
Another process, like a BGP daemon, should advertise the virtual IP address to the network . If needed, Keepalived can trigger whatever action is needed for this by using notify_* scripts. Until version 2.21 (not released yet), the interface directive is mandatory and Keepalived will transmit and receive VRRP packets on this interface only. If peers are reachable through several interfaces, like on a BGP on the host setup, you need a workaround. A simple one is to use a VXLAN interface: 
$ ip -6 link add keepalived6 type vxlan id 6 dstport 4789 local 2001:db8::10 nolearning
$ bridge fdb append 00:00:00:00:00:00 dev keepalived6 dst 2001:db8::11
$ bridge fdb append 00:00:00:00:00:00 dev keepalived6 dst 2001:db8::12
$ ip link set up dev keepalived6
Learning of MAC addresses is disabled and one generic entry for each peer is added in the forwarding database: transmitted packets are broadcasted to all peers, notably VRRP packets. Have a look at VXLAN & Linux for additional details. 
vrrp_instance gateway1  
  state BACKUP
  interface keepalived6
  mcast_src_ip 2001:db8::10
  virtual_router_id 12
  priority 101
  virtual_ipaddress  
    2001:db8:ff/64 dev lo
Starting from Keepalived 2.21, unicast_peer can be used without the interface directive. I think using VXLAN is still a neat trick applicable to other situations where communication using broadcast or multicast is needed, while the underlying network provide no support for this.

Vincent Bernat: Syncing NetBox with a custom Ansible module

The netbox.netbox collection from Ansible Galaxy provides several modules to update NetBox objects: 
- name: create a device in NetBox
  netbox_device:
    netbox_url: http://netbox.local
    netbox_token: s3cret
    data:
      name: to3-p14.sfo1.example.com
      device_type: QFX5110-48S
      device_role: Compute Switch
      site: SFO1
However, if NetBox is not your source of truth, you may want to ensure it stays in sync with your configuration management database1 by removing outdated devices or IP addresses. While it should be possible to glue together a playbook with a query, a loop and some filtering to delete unwanted elements, it feels clunky, inefficient and an abuse of YAML as a programming language. A specific Ansible module solves this issue and is likely more flexible.

Notice I recommend that you read Writing a custom Ansible module as an introduction, as well as Syncing MySQL tables for a first simpler example.

Code The module has the following signature and it syncs NetBox with the content of the provided YAML file: 
netbox_sync:
  source: netbox.yaml
  api: https://netbox.example.com
  token: s3cret
The synchronized objects are:
  • sites,
  • manufacturers,
  • device types,
  • device roles,
  • devices, and
  • IP addresses.
In our environment, the YAML file is generated from our configuration management database and contains a set of devices and a list of IP addresses: 
devices:
  ad2-p6.sfo1.example.com:
     datacenter: sfo1
     manufacturer: Cisco
     model: Catalyst 2960G-48TC-L
     role: net_tor_oob_switch
  to1-p6.sfo1.example.com:
     datacenter: sfo1
     manufacturer: Juniper
     model: QFX5110-48S
     role: net_tor_gpu_switch
# [ ]
ips:
  - device: ad2-p6.example.com
    ip: 172.31.115.18/21
    interface: oob
  - device: to1-p6.example.com
    ip: 172.31.115.33/21
    interface: oob
  - device: to1-p6.example.com
    ip: 172.31.254.33/32
    interface: lo0.0
# [ ]
The network team is not the sole tenant in NetBox. While adding new objects or modifying existing ones should be relatively safe, deleting unwanted objects can be risky. The module only deletes objects it did create or modify. To identify them, it marks them with a specific tag, cmdb. Most objects in NetBox accept tags.

Module definition Starting from the skeleton described in the previous article, we define the module: 
module_args = dict(
    source=dict(type='path', required=True),
    api=dict(type='str', required=True),
    token=dict(type='str', required=True, no_log=True),
    max_workers=dict(type='int', required=False, default=10)
)
result = dict(
    changed=False
)
module = AnsibleModule(
    argument_spec=module_args,
    supports_check_mode=True
)
It contains an additional optional arguments defining the number of workers to talk to NetBox and query the existing objects in parallel to speedup the execution.

Abstracting synchronization We need to synchronize different object types, but once we have a list of objects we want in NetBox, the grunt work is always the same:
  • check if the objects already exist,
  • retrieve them and put them in a form suitable for comparison,
  • retrieve the extra objects we don t want anymore,
  • compare the two sets, and
  • add missing objects, update existing ones, delete extra ones.
We code these behaviours into a Synchronizer abstract class. For each kind of object, a concrete class is built with the appropriate class attributes to tune its behaviour and a wanted() method to provide the objects we want. I am not explaining the abstract class code here. Have a look at the source if you want.

Synchronizing tags and tenants As a starter, here is how we define the class synchronizing the tags: 
class SyncTags(Synchronizer):
    app = "extras"
    table = "tags"
    key = "name"
    def wanted(self):
        return  "cmdb": dict(
            slug="cmdb",
            color="8bc34a",
            description="synced by network CMDB")
The app and table attributes defines the NetBox objects we want to manipulate. The key attribute is used to determine how to lookup for existing objects. In this example, we want to lookup tags using their names. The wanted() method is expected to return a dictionary mapping object keys to the list of wanted attributes. Here, the keys are tag names and we create only one tag, cmdb, with the provided slug, color and description. This is the tag we will use to mark the objects we create or modify. If the tag does not exist, it is created. If it exists, the provided attributes are updated. Other attributes are left untouched. We also want to create a specific tenant for objects accepting such an attribute (devices and IP addresses): 
class SyncTenants(Synchronizer):
    app = "tenancy"
    table = "tenants"
    key = "name"
    def wanted(self):
        return  "Network": dict(slug="network",
                                description="Network team")

Synchronizing sites We also need to synchronize the list of sites. This time, the wanted() method uses the information provided in the YAML file: it walks the devices and builds a set of datacenter names. 
class SyncSites(Synchronizer):
    app = "dcim"
    table = "sites"
    key = "name"
    only_on_create = ("status", "slug")
    def wanted(self):
        result = set(details["datacenter"]
                     for details in self.source['devices'].values()
                     if "datacenter" in details)
        return  k: dict(slug=k,
                        status="planned")
                for k in result
Thanks to the use of the only_on_create attribute, the specified attributes are not updated if they are different. The goal of this synchronizer is mostly to collect the references to the different sites for other objects. 
>>> pprint(SyncSites(**sync_args).wanted())
 'sfo1':  'slug': 'sfo1', 'status': 'planned' ,
 'chi1':  'slug': 'chi1', 'status': 'planned' ,
 'nyc1':  'slug': 'nyc1', 'status': 'planned'

Synchronizing manufacturers, device types and device roles The synchronization of manufacturers is pretty similar, except we do not use the only_on_create attribute: 
class SyncManufacturers(Synchronizer):
    app = "dcim"
    table = "manufacturers"
    key = "name"
    def wanted(self):
        result = set(details["manufacturer"]
                     for details in self.source['devices'].values()
                     if "manufacturer" in details)
        return  k:  "slug": slugify(k) 
                for k in result
Regarding the device types, we use the foreign attribute linking a NetBox attribute to the synchronizer handling it. 
class SyncDeviceTypes(Synchronizer):
    app = "dcim"
    table = "device_types"
    key = "model"
    foreign =  "manufacturer": SyncManufacturers 
    def wanted(self):
        result = set((details["manufacturer"], details["model"])
                     for details in self.source['devices'].values()
                     if "model" in details)
        return  k[1]: dict(manufacturer=k[0],
                           slug=slugify(k[1]))
                for k in result
The wanted() method refers to the manufacturer using its key attribute. In this case, this is the manufacturer name. 
>>> pprint(SyncManufacturers(**sync_args).wanted())
 'Cisco':  'slug': 'cisco' ,
 'Dell':  'slug': 'dell' ,
 'Juniper':  'slug': 'juniper' 
>>> pprint(SyncDeviceTypes(**sync_args).wanted())
 'ASR 9001':  'manufacturer': 'Cisco', 'slug': 'asr-9001' ,
 'Catalyst 2960G-48TC-L':  'manufacturer': 'Cisco',
                           'slug': 'catalyst-2960g-48tc-l' ,
 'MX10003':  'manufacturer': 'Juniper', 'slug': 'mx10003' ,
 'QFX10002-36Q':  'manufacturer': 'Juniper', 'slug': 'qfx10002-36q' ,
 'QFX10002-72Q':  'manufacturer': 'Juniper', 'slug': 'qfx10002-72q' ,
 'QFX5110-32Q':  'manufacturer': 'Juniper', 'slug': 'qfx5110-32q' ,
 'QFX5110-48S':  'manufacturer': 'Juniper', 'slug': 'qfx5110-48s' ,
 'QFX5200-32C':  'manufacturer': 'Juniper', 'slug': 'qfx5200-32c' ,
 'S4048-ON':  'manufacturer': 'Dell', 'slug': 's4048-on' ,
 'S6010-ON':  'manufacturer': 'Dell', 'slug': 's6010-on'
The device roles are defined like this: 
class SyncDeviceRoles(Synchronizer):
    app = "dcim"
    table = "device_roles"
    key = "name"
    def wanted(self):
        result = set(details["role"]
                     for details in self.source['devices'].values()
                     if "role" in details)
        return  k: dict(slug=slugify(k),
                        color="8bc34a")
                for k in result

Synchronizing devices A device is mostly a name with references to a role, a model, a datacenter and a tenant. These references are declared as foreign keys using the synchronizers defined previously. 
class SyncDevices(Synchronizer):
    app = "dcim"
    table = "devices"
    key = "name"
    foreign =  "device_role": SyncDeviceRoles,
               "device_type": SyncDeviceTypes,
               "site": SyncSites,
               "tenant": SyncTenants 
    remove_unused = 10
    def wanted(self):
        return  name: dict(device_role=details["role"],
                           device_type=details["model"],
                           site=details["datacenter"],
                           tenant="Network")
                for name, details in self.source['devices'].items()
                if  "datacenter", "model", "role"  <= set(details.keys())
The remove_unused attribute is a safety implemented to fail if we have to delete more than 10 devices: this may be the indication there is a bug somewhere, unless one of your datacenter suddenly caught fire. 
>>> pprint(SyncDevices(**sync_args).wanted())
 'ad2-p6.sfo1.example.com':  'device_role': 'net_tor_oob_switch',
                             'device_type': 'Catalyst 2960G-48TC-L',
                             'site': 'sfo1',
                             'tenant': 'Network' ,
 'to1-p6.sfo1.example.com':  'device_role': 'net_tor_gpu_switch',
                             'device_type': 'QFX5110-48S',
                             'site': 'sfo1',
                             'tenant': 'Network' ,
[ ]

Synchronizing IP addresses The last step is to synchronize IP addresses. We do not attach them to a device.2 Instead, we specify the device names in the description of the IP address: 
class SyncIPs(Synchronizer):
    app = "ipam"
    table = "ip-addresses"
    key = "address"
    foreign =  "tenant": SyncTenants 
    remove_unused = 1000
    def wanted(self):
        wanted =  
        for details in self.source['ips']:
            if details['ip'] in wanted:
                wanted[details['ip']]['description'] = \
                    f" details['device']  (and others)"
            else:
                wanted[details['ip']] = dict(
                    tenant="Network",
                    status="active",
                    dns_name="",        # information is present in DNS
                    description=f" details['device'] :  details['interface'] ",
                    role=None,
                    vrf=None)
        return wanted
There is a slight difficulty: NetBox allows duplicate IP addresses, so a simple lookup is not enough. In case of multiple matches, we choose the best by preferring those tagged with cmdb, then those already attached to an interface: 
def get(self, key):
    """Grab IP address from NetBox."""
    # There may be duplicate. We need to grab the "best".
    results = super(Synchronizer, self).get(key)
    if len(results) == 0:
        return None
    if len(results) == 1:
        return results[0]
    scores = [0]*len(results)
    for idx, result in enumerate(results):
        if "cmdb" in result.tags:
            scores[idx] += 10
        if result.interface is not None:
            scores[idx] += 5
    return sorted(zip(scores, results),
                  reverse=True, key=lambda k: k[0])[0][1]

Getting the current and wanted states Each synchronizer is initialized with a reference to the Ansible module, a reference to a pynetbox s API object, the data contained in the provided YAML file and two empty dictionaries for the current and expected states: 
source = yaml.safe_load(open(module.params['source']))
netbox = pynetbox.api(module.params['api'],
                      token=module.params['token'])
sync_args = dict(
    module=module,
    netbox=netbox,
    source=source,
    before= ,
    after= 
)
synchronizers = [synchronizer(**sync_args) for synchronizer in [
    SyncTags,
    SyncTenants,
    SyncSites,
    SyncManufacturers,
    SyncDeviceTypes,
    SyncDeviceRoles,
    SyncDevices,
    SyncIPs
]]
Each synchronizer has a prepare() method whose goal is to compute the current and wanted states. It returns True in case of a difference: 
# Check what needs to be synchronized
try:
    for synchronizer in synchronizers:
        result['changed']  = synchronizer.prepare()
except AnsibleError as e:
    result['msg'] = e.message
    module.fail_json(**result)

Applying changes Back to the skeleton described in the previous article, the last step is to apply the changes if there is a difference between these states. Each synchronizer registers the current and wanted states in sync_args["before"][table] and sync_args["after"][table] where table is the name of the table for a given NetBox object type. The diff object is a bit elaborate as it is built table by table. This enables Ansible to display the name of each table before the diff representation: 
# Compute the diff
if module._diff and result['changed']:
    result['diff'] = [
        dict(
            before_header=table,
            after_header=table,
            before=yaml.safe_dump(sync_args["before"][table]),
            after=yaml.safe_dump(sync_args["after"][table]))
        for table in sync_args["after"]
        if sync_args["before"][table] != sync_args["after"][table]
    ]
# Stop here if check mode is enabled or if no change
if module.check_mode or not result['changed']:
    module.exit_json(**result)
Each synchronizer also exposes a synchronize() method to apply changes and a cleanup() method to delete unwanted objects. Order is important due to the relation between the objects. 
# Synchronize
for synchronizer in synchronizers:
    synchronizer.synchronize()
for synchronizer in synchronizers[::-1]:
    synchronizer.cleanup()
module.exit_json(**result)
The complete code is available on GitHub. Compared to using netbox.netbox collection, the logic is written in Python instead of trying to glue Ansible tasks together. I believe this is both more flexible and easier to read, notably when trying to delete outdated objects. While I did not test it, it should also be faster. An alternative would have been to reuse code from the netbox.netbox collection, as it contains similar primitives. Unfortunately, I didn t think of it until now.
  1. In my opinion, a good option for a source of truth is to use YAML files in a Git repository. You get versioning for free and people can get started with a text editor.
  2. This limitation is mostly due to laziness: we do not really care about this information. Our main motivation for putting IP addresses in NetBox is to keep track of the used IP addresses. However, if an IP address is already attached to an interface, we leave this association untouched.

Russell Coker: Burning Lithium Ion Batteries

I had an old Nexus 4 phone that was expanding and decided to test some of the theories about battery combustion. The first claim that often gets made is that if the plastic seal on the outside of the battery is broken then the battery will catch fire. I tested this by cutting the battery with a craft knife. With every cut the battery sparked a bit and then when I levered up layers of the battery (it seems to be multiple flat layers of copper and black stuff inside the battery) there were more sparks. The battery warmed up, it s plausible that in a confined environment that could get hot enough to set something on fire. But when the battery was resting on a brick in my backyard that wasn t going to happen. The next claim is that a Li-Ion battery fire will be increased with water. The first thing to note is that Li-Ion batteries don t contain Lithium metal (the Lithium high power non-rechargeable batteries do). Lithium metal will seriously go off it exposed to water. But lots of other Lithium compounds will also react vigorously with water (like Lithium oxide for example). After cutting through most of the center of the battery I dripped some water in it. The water boiled vigorously and the corners of the battery (which were furthest away from the area I cut) felt warmer than they did before adding water. It seems that significant amounts of energy are released when water reacts with whatever is inside the Li-Ion battery. The reaction was probably giving off hydrogen gas but didn t appear to generate enough heat to ignite hydrogen (which is when things would really get exciting). Presumably if a battery was cut in the presence of water while in an enclosed space that traps hydrogen then the sparks generated by the battery reacting with air could ignite hydrogen generated from the water and give an exciting result. It seems that a CO2 fire extinguisher would be best for a phone/tablet/laptop fire as that removes oxygen and cools it down. If that isn t available then a significant quantity of water will do the job, water won t stop the reaction (it can prolong it), but it can keep the reaction to below 100C which means it won t burn a hole in the floor and the range of toxic chemicals released will be reduced. The rumour that a phone fire on a plane could do a China syndrome type thing and melt through the Aluminium body of the plane seems utterly bogus. I gave it a good try and was unable to get a battery to burn through it s plastic and metal foil case. A spare battery for a laptop in checked luggage could be a major problem for a plane if it ignited. But a battery in the passenger area seems unlikely to be a big problem if plenty of water is dumped on it to prevent the plastic case from burning and polluting the air. I was not able to get a result that was even worthy of a photograph. I may do further tests with laptop batteries.
Related posts:
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  2. Hydrogen Powered Cars Will Never Work One of the most important issues for a commodity fuel...
  3. Base Load Solar Power A frequent criticism of solar power is that the sun...

18 September 2020

Daniel Lange: Fixing the Nextcloud menu to show more than eight application icons

I have been late to adopt an on-premise cloud solution as the security of Owncloud a few years ago wasn't so stellar (cf. my comment from 2013 in Encryption files ... for synchronization across the Internet). But the follow-up product Nextcloud has matured quite nicely and we use it for collaboration both in the company and in FLOSS related work at multiple nonprofit organizations. There is a very annoying "feature" in Nextcloud though that the designers think menu items for apps at the top need to be limited to eight or less to prevent information overload in the header. The whole item discussion is worth reading as it it an archetypical example of design prevalence vs. user choice. And of course designers think they are right. That's a feature of the trade.
And because they know better there is no user configurable option to extend that 8 items to may be 12 or so which would prevent the annoying overflow menu we are seeing with 10 applications in use: Screenshot of stock Nextcloud menu Luckily code can be changed and there are many comments floating around the Internet to change const minAppsDesktop = 8. In this case it is slightly complicated by the fact that the javascript code is distributed in compressed form (aka "minified") as core/js/dist/main.js and you probably don't want to build the whole beast locally to change one constant. Basically
const breakpoint_mobile_width = 1024;

const resizeMenu = () =>
const appList = $('#appmenu li')
const rightHeaderWidth = $('.header-right').outerWidth()
const headerWidth = $('header').outerWidth()
const usePercentualAppMenuLimit = 0.33
const minAppsDesktop = 8
let availableWidth = headerWidth - $('#nextcloud').outerWidth() - (rightHeaderWidth > 210 ? rightHeaderWidth : 210)
const isMobile = $(window).width() < breakpoint_mobile_width
if (!isMobile)
availableWidth = availableWidth * usePercentualAppMenuLimit

let appCount = Math.floor((availableWidth / $(appList).width()))
if (isMobile && appCount > minAppsDesktop)
appCount = minAppsDesktop

if (!isMobile && appCount < minAppsDesktop)
appCount = minAppsDesktop


// show at least 2 apps in the popover
if (appList.length - 1 - appCount >= 1)
appCount--


$('#more-apps a').removeClass('active')
let lastShownApp
for (let k = 0; k < appList.length - 1; k++)
const name = $(appList[k]).data('id')
if (k < appCount)
$(appList[k]).removeClass('hidden')
$('#apps li[data-id=' + name + ']').addClass('in-header')
lastShownApp = appList[k]
else
$(appList[k]).addClass('hidden')
$('#apps li[data-id=' + name + ']').removeClass('in-header')
// move active app to last position if it is active
if (appCount > 0 && $(appList[k]).children('a').hasClass('active'))
$(lastShownApp).addClass('hidden')
$('#apps li[data-id=' + $(lastShownApp).data('id') + ']').removeClass('in-header')
$(appList[k]).removeClass('hidden')
$('#apps li[data-id=' + name + ']').addClass('in-header')




// show/hide more apps icon
if ($('#apps li:not(.in-header)').length === 0)
$('#more-apps').hide()
$('#navigation').hide()
else
$('#more-apps').show()

gets compressed during build time to become part of one 15,000+ character line. The relevant portion reads:
var f=function() var e=s()("#appmenu li"),t=s()(".header-right").outerWidth(),n=s()("header").outerWidth()-s()("#nextcloud").outerWidth()-(t>210?t:210),i=s()(window).width()<1024;i (n*=.33);var r,o=Math.floor(n/s()(e).width());i&&o>8&&(o=8),!i&&o<8&&(o=8),e.length-1-o>=1&&o--,s()("#more-apps a").removeClass("active");for(var a=0;a<e.length-1;a++) var l=s()(e[a]).data("id");a<o?(s()(e[a]).removeClass("hidden"),s()("#apps li[data-id="+l+"]").addClass("in-header"),r=e[a]):(s()(e[a]).addClass("hidden"),s()("#apps li[data-id="+l+"]").removeClass("in-header"),o>0&&s()(e[a]).children("a").hasClass("active")&&(s()(r).addClass("hidden"),s()("#apps li[data-id="+s()(r).data("id")+"]").removeClass("in-header"),s()(e[a]).removeClass("hidden"),s()("#apps li[data-id="+l+"]").addClass("in-header"))) 0===s()("#apps li:not(.in-header)").length?(s()("#more-apps").hide(),s()("#navigation").hide()):s()("#more-apps").show()
Well, we can still patch that, can we? Continue reading "Fixing the Nextcloud menu to show more than eight application icons"

Sven Hoexter: Avoiding the GitHub WebUI

Now that GitHub released v1.0 of the gh cli tool, and this is all over HN, it might make sense to write a note about my clumsy aliases and shell functions I cobbled together in the past month. Background story is that my dayjob moved to GitHub coming from Bitbucket. From my point of view the WebUI for Bitbucket is mediocre, but the one at GitHub is just awful and painful to use, especially for PR processing. So I longed for the terminal and ended up with gh and wtfutil as a dashboard. The setup we have is painful on its own, with several orgs and repos which are more like monorepos covering several corners of infrastructure, and some which are very focused on a single component. All workflows are anti GitHub workflows, so you must have permission on the repo, create a branch in that repo as a feature branch, and open a PR for the merge back into master. gh functions and aliases 
# setup a token with perms to everything, dealing with SAML is a PITA
export GITHUB_TOKEN="c0ffee4711"
# I use a light theme on my terminal, so adjust the gh theme
export GLAMOUR_STYLE="light"
#simple aliases to poke at a PR
alias gha="gh pr review --approve"
alias ghv="gh pr view"
alias ghd="gh pr diff"
### github support functions, most invoked with a PR ID as $1
#primary function to review PRs
function ghs  
    gh pr view $ 1 
    gh pr checks $ 1 
    gh pr diff $ 1 
 
# very custom PR create function relying on ORG and TEAM settings hard coded
# main idea is to create the PR with my team directly assigned as reviewer
function ghc  
    if git status   grep -q 'Untracked'; then
        echo "ERROR: untracked files in branch"
        git status
        return 1
    fi
    git push --set-upstream origin HEAD
    gh pr create -f -r "$(git remote -v   grep push   grep -oE 'myorg-[a-z]+')/myteam"
 
# merge a PR and update master if we're not in a different branch
function ghm  
    gh pr merge -d -r $ 1 
    if [[ "$(git rev-parse --abbrev-ref HEAD)" == "master" ]]; then
        git pull
    fi
 
# get an overview over the files changed in a PR
function ghf  
    gh pr diff $ 1    diffstat -l
 
# generate a link to a commit in the WebUI to pass on to someone else
# input is a git commit hash
function ghlink  
    local repo="$(git remote -v   grep -E "github.+push"   cut -d':' -f 2   cut -d'.' -f 1)"
    echo "https://github.com/$ repo /commit/$ 1 "
wtfutil I have a terminal covering half my screensize with small dashboards listing PRs for the repos I care about. For other repos I reverted back to mail notifications which get sorted and processed from time to time. A sample dashboard config looks like this: 
github_admin:
  apiKey: "c0ffee4711"
  baseURL: ""
  customQueries:
    othersPRs:
      title: "Pull Requests"
      filter: "is:open is:pr -author:hoexter -label:dependencies"
  enabled: true
  enableStatus: true
  showOpenReviewRequests: false
  showStats: false
  position:
    top: 0
    left: 0
    height: 3
    width: 1
  refreshInterval: 30
  repositories:
    - "myorg/admin"
  uploadURL: ""
  username: "hoexter"
  type: github
The -label:dependencies is used here to filter out dependabot PRs in the dashboard. Workflow Look at a PR with ghv $ID, if it's ok ACK it with gha $ID. Create a PR from a feature branch with ghc and later on merge it with ghm $ID. The $ID is retrieved from looking at my wtfutil based dashboard. Security Considerations The world is full of bad jokes. For the WebUI access I've the full array of pain with SAML auth, which expires too often, and 2nd factor verification for my account backed by a Yubikey. But to work with the CLI you basically need an API token with full access, everything else drives you insane. So I gave in and generated exactly that. End result is that I now have an API token - which is basically a password - which has full power, and is stored in config files and environment variables. So the security features created around the login are all void now. Was that the aim of it after all?

17 September 2020

Dirk Eddelbuettel: RcppSpdlog 0.0.1: New and Exciting Logging Package

Very thrilled to announce a new package RcppSpdlog which is now on CRAN in its first release 0.0.1. We had tweeted once about the earliest version which had already caught the eyes of Gabi upstream. RcppSpdlog bundles spdlog, a wonderful header-only C++ logging library with all the bells and whistles you would want that was written by Gabi Melman, and also includes fmt by Victor Zverovic. I had meant to package this for a few years now but didn t find an (easy, elegant) way to completely lift stdout / stderr and related uses which R wants us to remove for smoother operations from R itself including synchronized input/output. It was only a few weeks ago that I realized I should subclass a logger (or, more concretely, a sink for a logger) which could then use R input/output. With the right idea the implementaton was easy, and [Gabi]((https://github.com/gabime) was most helpful in making sure R CMD check would not see one or two remaining C++ i/o operations (which we currently do by not activating a default logger, and substituing REprintf() in one call). So this is now clean and sween and a simple use is included in an example in the package we can show here too (in slightly shorter form minus the documentation header): 
// this portmanteau include also defines the r_sink we use below, and which
// diverts all logging to R via the Rcpp::Rcout replacement for std::cout
#include <RcppSpdlog>

// [[Rcpp::export]]
void exampleRsink()  

    std::string logname = "fromR";                          // fix a name for this logger
    auto sp = spdlog::get(logname);                         // retrieve existing one
    if (sp == nullptr) sp = spdlog::r_sink_mt(logname);     // or create new one if needed

    // change log pattern (changed from [%H:%M:%S %z] [%n] [%^---%L---%$] )
    sp->set_pattern("[%H:%M:%S.%f] [%n] [%^%L%$] [thread %t] %v");

    sp->info("Welcome to spdlog!");
    sp->error("Some error message with arg:  ", 1);

    sp->warn("Easy padding in numbers like  :08d ", 12);
    sp->critical("Support for int:  0:d ;  hex:  0:x ;  oct:  0:o ; bin:  0:b ", 42);
    sp->info("Support for floats  :03.2f ", 1.23456);
    sp->info("Positional args are  1   0 ..", "too", "supported");
    sp->info(" :<30 ", "left aligned");
The NEWS entry for the first release follows.

Changes in RcppSpdlog version 0.0.1 (2020-09-08)
  • Initial release with added R/Rcpp logging sink example

The only sour grapes, if any, are over the CRAN processing. This was originally uploaded three weeks ago. As a new package, it got extra attention and some truly idiosyncratic attention to two details that were already supplied in the first uploaded version. Yet it needed two rounds of going back and forth for really no great net gain, yet wasting a week each time. I am not all that impressed by this, and not particularly pleased either, but I presume is the tax we all pay in order to enjoy the unsurpassed richness of the CRAN repository system which continues to work just flawlessly. If you like this or other open-source work I do, you can now sponsor me at GitHub. For the first year, GitHub will match your contributions.

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

15 September 2020

Rapha&#235;l Hertzog: Freexian s report about Debian Long Term Support, August 2020

A Debian LTS logo Like each month, here comes a report about the work of paid contributors to Debian LTS. Individual reports In August, 237.25 work hours have been dispatched among 14 paid contributors. Their reports are available: Evolution of the situation August was a regular LTS month once again, even though it was only our 2nd month with Stretch LTS.
At the end of August some of us participated in DebConf 20 online where we held our monthly team meeting. A video is available.
As of now this video is also the only public resource about the LTS survey we held in July, though a written summary is expected to be released soon. The security tracker currently lists 56 packages with a known CVE and the dla-needed.txt file has 55 packages needing an update. Thanks to our sponsors Sponsors that recently joined are in bold.

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