Reproducible Builds in November 2023

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

Reproducible Builds Summit 2023

Between October 31st and November 2nd, we held our seventh Reproducible Builds Summit in Hamburg, Germany! Amazingly, the agenda and all notes from all sessions are all online — many thanks to everyone who wrote notes from the sessions.

As a followup on one idea, started at the summit, Alexander Couzens and Holger Levsen started work on a cache (or tailored front-end) for the service. The general idea is that, when rebuilding Debian, you do not actually need the whole ~140TB of data from; rather, only a very small subset of the packages are ever used for for building. It turns out, for amd64, arm64, armhf, i386, ppc64el, riscv64 and s390 for Debian trixie, unstable and experimental, this is only around 500GB — ie. less than 1%. Although the new service not yet ready for usage, it has already provided a promising outlook in this regard. More information is available on and we hope that this service becomes usable in the coming weeks.

The adjacent picture shows a sticky note authored by Jan-Benedict Glaw at the summit in Hamburg, confirming Holger Levsen’s theory that rebuilding all Debian packages needs a very small subset of packages, the text states that 69,200 packages (in Debian sid) list 24,850 packages in their .buildinfo files, in 8,0200 variations. This little piece of paper was the beginning of rebuilder-snapshot and is a direct outcome of the summit!

The Reproducible Builds team would like to thank our event sponsors who include Mullvad VPN, openSUSE, Debian, Software Freedom Conservancy, Allotropia and Aspiration Tech.

Beyond Trusting FOSS presentation at SeaGL

On November 4th, Vagrant Cascadian presented Beyond Trusting FOSS at SeaGL in Seattle, WA in the United States. Founded in 2013, SeaGL is a free, grassroots technical summit dedicated to spreading awareness and knowledge about free source software, hardware and culture. The summary of Vagrant’s talk mentions that it will:

[…] introduce the concepts of Reproducible Builds, including best practices for developing and releasing software, the tools available to help diagnose issues, and touch on progress towards solving decades-old deeply pervasive fundamental security issues… Learn how to verify and demonstrate trust, rather than simply hoping everything is OK!

Germane to the contents of the talk, the slides for Vagrant’s talk can be built reproducibly, resulting in a PDF with a SHA1 of cfde2f8a0b7e6ec9b85377eeac0661d728b70f34 when built on Debian bookworm and c21fab273232c550ce822c4b0d9988e6c49aa2c3 on Debian sid at the time of writing.

Human Factors in Software Supply Chain Security

Marcel Fourné, Dominik Wermke, Sascha Fahl and Yasemin Acar have published an article in a Special Issue of the IEEE’s Security & Privacy magazine. Entitled A Viewpoint on Human Factors in Software Supply Chain Security: A Research Agenda, the paper justifies the need for reproducible builds to reach developers and end-users specifically, and furthermore points out some under-researched topics that we have seen mentioned in interviews. An author pre-print of the article is available in PDF form.

Community updates

On our mailing list this month:

  • Julien Lepiller mentioned that they were interested in translating our website, and provided offered GNU Guix’s translation framework (Weblate) as a potential model to emulate.

  • Bernhard M. Wiedemann posted a positive “LibreOffice success story” documenting that, after some work:

    […] today I hold in my hands the first two bit-identical LibreOffice rpm packages. And this is the success I wanted to share with you all today [and] it makes me feel as if we can solve anything.

  • kpcyrd reported on their excellent results with making esp32c3 microcontroller firmware reproducible with Rust, repro-env and Arch Linux:

    I chose the esp32c3 [board] because it has good Rust support from the esp-rs project, and you can get a dev board for about 6-8€. To document my build environment I used repro-env together with Arch Linux because its archive is very reliable and contains all the different Rust development tools I needed.

  • Separate to their work on LibreOffice however, Bernhard M. Wiedemann also requested assistance with a number of packages that so far refuse to build reproducibly. He writes that “the common theme around them is that they use scheme or lisp to produce binaries with a dump command” and hopes that someone may be able to help.

  • Finally, Fay Stegerman regrettably reports that she will no longer be able to work on Android reproducible builds nor update the Reproducible Builds community with the status of reproducibility within F-Droid.

openSUSE updates

Bernhard M. Wiedemann has created a wiki page outlining an proposal to create a general-purpose Linux distribution which consists of 100% bit-reproducible packages… albeit minus the embedded signature within RPM files. It would be based on openSUSE Tumbleweed or, if available, its Slowroll-variant.

In addition, Bernhard posted another monthly update for his work elsewhere in openSUSE.

As recently reported in the most recent Debian Developer News, Paul Gevers has integrated a package’s reproducibility status into the way Debian ‘migrates’ packages into the next stable release. For the amd64, arm64, i386 and armhf architectures, data is collected from the Reproducible Builds testing framework is collected by this migration software even though, at the time of writing, it neither causes nor migration bonuses nor blocks migration. Indeed, the information only results are visible on Britney’s excuses as well as on individual packages’ pages on

Ubuntu Launchpad now supports .buildinfo files

Back in 2017, Steve Langasek filed a bug against Ubuntu’s Launchpad code hosting platform to report that .changes files (artifacts of building Ubuntu and Debian packages) reference .buildinfo files that aren’t actually exposed by Launchpad itself. This was causing issues when attempting to process .changes files with tools such as Lintian. However, it was noticed last month that, in early August of this year, Simon Quigley had resolved this issue, and .buildinfo files are now available from the Launchpad system.

PHP reproducibility updates

There have been two updates from the PHP programming language this month.

Firstly, the widely-deployed PHPUnit framework for the PHP programming language have recently released version 10.5.0, which introduces the inclusion of a composer.lock file, ensuring total reproducibility of the shipped binary file. Further details and the discussion that went into their particular implementation can be found on the associated GitHub pull request.

In addition, the presentation “Leveraging Nix in the PHP ecosystem” has been given in late October at the PHP International Conference in Munich by Pol Dellaiera. While the video replay is not yet available, the (reproducible) presentation slides and speaker notes are available.

diffoscope changes

diffoscope is our in-depth and content-aware diff utility that can locate and diagnose reproducibility issues. This month, Chris Lamb made a number of changes, including:

  • Improving DOS/MBR extraction by adding support for 7z. []
  • Adding a missing RequiredToolNotFound import. []
  • As a UI/UX improvement, try and avoid printing an extended traceback if diffoscope runs out of memory. []
  • Mark diffoscope as ‘stable’ on []
  • Uploading version 252 to Debian unstable. []

  • Vagrant Cascadian updated diffoscope in GNU Guix to version [252][].

Website updates

A huge number of notes were added to our website that were taken at our recent Reproducible Builds Summit held between October 31st and November 2nd in Hamburg, Germany. In particular, a big thanks to Arnout Engelen, Bernhard M. Wiedemann, Daan De Meyer, Evangelos Ribeiro Tzaras, Holger Levsen and Orhun Parmaksız.

In addition to this, a number of other changes were made, including:

Upstream patches

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

Reproducibility testing framework

The Reproducible Builds project operates a comprehensive testing framework (available at in order to check packages and other artifacts for reproducibility. In November, a number of changes were made by Holger Levsen:

  • Debian-related changes:

    • Track packages marked as Priority: important in a new package set. [][]
    • Stop scheduling packages that fail to build from source in bookworm [] and bullseye. [].
    • Add old releases dashboard link in web navigation. []
    • Permit re-run of the pool_buildinfos script to be re-run for a specific year. []
    • Grant jbglaw access to the osuosl4 node [][] along with lynxis [].
    • Increase RAM on the amd64 Ionos builders from 48 GiB to 64 GiB; thanks IONOS! []
    • Move buster to archived suites. [][]
    • Reduce the number of arm64 architecture workers from 24 to 16 in order to improve stability [], reduce the workers for amd64 from 32 to 28 and, for i386, reduce from 12 down to 8 [].
    • Show the entire build history of each Debian package. []
    • Stop scheduling already tested package/version combinations in Debian bookworm. []
  • Snapshot service for rebuilders

  • System-health:

    • Detect failures due to HTTP “503 Service Unavailable” errors. []
    • Detect failures to update package sets. []
    • Detect unmet dependencies. (This usually occurs with builds of Debian live-build.) []
  • Misc-related changes:

    • do install systemd-ommd on jenkins. []
    • fix harmless typo in squid.conf for codethink04. []
    • fixup: reproducible Debian: add gunicorn service to serve /api for rebuilder-snapshot.d.o. []
    • Increase codethink04’s Squid cache_dir size setting to 16 GiB. []
    • Don’t install systemd-oomd as it unfortunately kills sshd… []
    • Use debootstrap from backports when commisioning nodes. []
    • Add the live_build_debian_stretch_gnome, debsums-tests_buster and debsums-tests_buster jobs to the “zombie” list. [][]
    • Run jekyll build with the --watch argument when building the Reproducible Builds website. []
    • Misc node maintenance. [][][]

Other changes were made as well, however, including Mattia Rizzolo fixing rc.local’s Bash syntax so it can actually run [], commenting away some file cleanup code that is (potentially) deleting too much [] and fixing the html_brekages page for Debian package builds []. Finally, наб diagnosed and submitted a patch to add a AddEncoding gzip .gz line to the Apache configuration so that Gzip files aren’t re-compressed as Gzip which some clients can’t deal with (as well as being a waste of time). []

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

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