Application - Core Developer - Jonas Jelten

Community Ubuntu Developer Membership
1

I, Jonas Jelten, am applying for upload rights for Ubuntu core developer rights.

Name Jonas Jelten
Launchpad Page https://launchpad.net/~jj
GitHub Page https://github.com/TheJJ
Matrix @jj → :sft.lol

I am applying because:

  • I’d like to reduce sponsorship burden on my team ✓
  • I’d like to eliminate delays in getting my work sponsored ✓
  • I need the ability to restart failed builds independently to save others’ time ✓
  • I want to help sponsor and mentor other contributors, enabling more community work to land ✓
  • Increasing my direct involvement allows me to better assess and implement improvements for distribution tooling and infrastructure ✓ :smile:

Who I am

Hey! I am Jonas (jj), a software engineer within the Ubuntu Server team.
My primary focus is creating updates and bugfixes for various Ubuntu packages, as well as developing and maintaining project and team infrastructure.
Currently, I am actively improving and extending git-ubuntu, our daily triage tooling (startriage, which may be useful for your team!), and Ubuntu’s debuginfod.

Before joining Ubuntu, I worked at the IT Operations datacenter at the Technical University of Munich (TUM), I studied there before. Among many infrastructure improvements and new services (LXD, BBB, Ceph, …), I created ceph-balancer, an advanced optimization tool designed to increase available storage in Ceph clusters.

Outside of work, I collaborate with friends on projects I find interesting.
Some of these relate closely to Debian/Ubuntu, such as our vision for modernized .deb packaging with debmagic :magic_wand:.
My open game engine for Age of Empires has attracted over 14k stars on GitHub.
I drove the development of StuStaPay, an electronic NFC-based payment system for large-scale events (I co-organize StuStaCulum).
This system runs on the infrastructure of StuStaNet, a non-profit ISP organization where I remain an active contributor.
I’m driven by the infinity of available inventions and improvements in the (free) software world, so we can have more happy places of awesomeness!

My Ubuntu story

My journey began in 2008. After hearing about Ubuntu from a friend, I quickly discovered that the free software world was my true home.
While I experimented with Arch and Gentoo to curiously discover how a Linux distribution works internally and to customize it, I always kept Debian and Ubuntu as the standard for my servers.

During my studies, I worked for the StuStaNet ISP, which runs entirely on Debian.
Later, at the TUM ITO datacenter, nearly all of the thousands of machines powering the university and research infrastructure were running Ubuntu.
To take my free software contributions to the next level, I decided to work for Ubuntu full-time, and I am now proud to be part of the Ubuntu Server engineering team.

Examples of my work / Things I’m proud of

Quick links: Uploads on UDD, Launchpad Uploads

Below is a selection of my contributions since May 2025 until January 2026.

Ubuntu contributions

main inclusion requests

feature freeze exceptions

fixes and SRUs

merges and syncs

upstream contributions

Areas of work

Currently my involvement is:

  • Packages
    • openldap
    • multipath-tools
    • nginx
    • ipxe
    • sssd
    • dovecot
    • postfix
    • unbound
    • bacula
    • lftp
    • strace
    • and drive-by contributions and backports in various other packages
  • Infrastructure & tooling
    • git-ubuntu
    • startriage
    • ubuntu-debuginfod
    • debmagic

I work within the Ubuntu Server team, collaborating closely with my colleagues to ensure precise and reliable delivery.

Things I could do better

  • In reviews or design decisions details are important, but I can improve on focusing more on more the overall effects and bigger picture.
  • I should investigate more infrastructure bugs, and if possible propose fixes.
  • I’d like to focus more on meaningful contributions, to better priorize among the infinity of todos.

Plans for the future

General

I intend to encourage and unblock more contributions to Ubuntu by sponsoring community uploads and decreasing the workload on my team members by handling my uploads independently.

My long-term goal is to modernize distribution tooling.
I want to improve components in the current architecture and resolve pain points to enable better working with Ubuntu and Debian, there’s lots of opportunities. I’m working with Launchpad to get a better integration of git through git-ubuntu.

When I become a Core Dev, this allows me to drive improvements in the distro architecture and infrastructure so that everyone can benefit from a stronger foundation.

What I like least in Ubuntu

  • The packaging tooling and infrastructure could benefit a lot from vast improvements.
    For example the autopkgtests and proposed-migration, tracking package file names or debugging symbols should be integrated and made available in real-time in Launchpad.
    The code review UI could be modernized and more integrated and tailored towards Ubuntu development.
    Overall, the number of tools duct-taped onto the Launchpad API is really worrying.
  • The flow of testing package uploads by creating a PPA, creating a source pkg, uploading, running (and making sure to re-trigger) autopkgtest, waiting for results, creating merge proposals, approving should be more automated - I’m working with Launchpad to get improvements here :slight_smile:
  • Debian integration could also be better, like full-automatic update merges (a preview version of this I’ve created in git ubuntu deltarebase, salsa/dgit and git-ubuntu history sharing.
  • A lot of the packaging internals is crafted with rather legacy technologies (Perl and Bash codebases) where seemingly few people dare to touch it, and if, tools remain isolated and quite unmaintained.
    Thus, many tools have been stacked metre-high on top to improve weakenesses in the tool below, but that whole stack isn’t integrated well and each layer missing different features - I wish collaboration and integration of such tools would be increased.
  • I’d love to see more git-based packaging in general, since mixing (or even loosing) rich history due to a lacking upload standard is annoying. I think when the git tooling is good enough, we should completely switch away from tar-based uploads and use git exclusively.
    There’s some remaining problems and usability issues until we’re there, but we should work towards improving.

Endorsements and Comments

If you’ve worked with me or can judge my contributions and their quality, I’d be glad about an endorsement reply to this post :smile:

Endorsement comment inspiration for you:

- Sponsoring feedback
  Please fill us in on your shared experience.
  - What did you sponsor? A list of sponsored packages can generated [via UDD here](https://udd.debian.org/cgi-bin/ubuntu-sponsorships.cgi)
  - How would you judge the quality and describe the improvements?
  - Do you trust the applicant?
- Specific experiences of working together
  - good examples of your work together, also cases that could have handled better.
- Areas of improvement and next steps
  - What is the journey you see ahead of the applicant, the next steps they should take, the next things they likely have to learn and the next mountains to climb?
5 Likes
2

I endorse Jonas for Ubuntu Core Developer. I’m confident he can be trusted with unsupervised upload rights to Ubuntu.

I think I only sponsored one upload for Jonas (cloud-initramfs-tools)). The work was clean, and followed our processes. But my endorsement does not rest on sponsorship volume. My confidence in Jonas comes mainly from repeated in-depth technical discussions on packaging, autopkgtest, Ubuntu processes, and distro development in general. Over many of these conversations Jonas showed strong technical knowledge, sound judgement, and a clear understanding of Ubuntu development practices.

I also reviewed the work he lists in his application. It is solid and confirmed the same picture. This further built my confidence in his abilities and trust that he can be given Core Dev status.

Other than ramping up sponsoring and Patch Pilot work once he has upload rights, I’d like to see Jonas increasing the scope in the tooling improvements he’s already driving.

2 Likes
3

General feedback

I have worked with Jonas from May 2025 to February 2026 as his Ubuntu mentor, while we were both part of the Ubuntu Server team. Due to his prior experience as an open-source contributor and Gentoo packager, he hit the ground running and quickly picked up the Debian/Ubuntu-specific tooling and approach to distro work. When walking through the different tools together, Jonas always went deep to understand the inner workings, spotting misconceptions and raising bugs/fixes several times. He showed a great learning ability too, as he got into the debuginfod and git-ubuntu projects quickly, adding new features, improving the infrastructure, and contributing plenty of ideas for future developments.

Jonas actively contributes to the Ubuntu Server team bug & documentation triage process, keeping the team’s bug work under control and fixing high-priority bugs, such as FTBFS (LP: #2125198). He is always attentive and curious about new things that he reads about in git history and does not hesitate to ask questions to the relevant people if anything is unclear.

I sponsored 7 packages for Jonas, which can be seen from the list below. This number is relatively low, because I always encouraged him to seek sponsorship from others first before falling back to me (the mentor). Jonas did that in most cases, gaining experience and insights from a multitude of core-devs and reviewers.

sponsored by slyon:

Jonas worked his way through proposed-migration, keeping the team packages in good shape and learning about all the relationships between packages, transitions, autopkgtest CI and the processes involved. He drove the bacula MIR (LP: #2112455) that was requested by the IS team at the time. I trust in his skills and decision-making in the best interest of the Ubuntu community.

I fully endorse his application for Ubuntu Core-Dev.

Specific Experiences of working together

Besides supporting Jonas’ distro work (as described above) and collaborating on the common Ubuntu Server team chores, I was (one of many) sparring partner for debmagic. His work on this new build tool clearly shows a deep understanding of the Debian build & test pipeline, integrating best practices from more modern approaches (Gentoo, Nix, ..) and his attention to details and edge cases.
This is pretty much the same statement I gave for his PPU application, because we didn’t collaborate a lot after I left the team shortly after he gained his Server team package-set upload rights. But Jonas was at a very strong level back then already, and I see he collected lots of upload under his belt since then and got deeper into distro tooling, such as git-ubuntu, debmagic and startriage, which shows his dedication and strong understanding of processes and the technical ecosystem.

Areas of Improvement

As stated in my previous PPU endorsement, I’d like to see Jonas participate in +1 Maintenance rotations, as I couldn’t find any public reports for the last couple of months. Also, I’d like to encourage him to be pragmatic at times; diving deep and questioning everything is great and powerful, but it can also lead to slowness in getting things done. Sometimes a shortcoming should be accepted for the sake of progress. It can then still be tackled at a later point in time.

1 Like
4

I’m also endorsing Jonas for his coredev applications. I’ve only directly sponsored a few uploads and syncs for him but I’ve worked with him more on the charming of Ubuntu services and had several opportunities to discuss Ubuntu bug and packaging.

I’ve confidence he has the technical knowledge and the Ubuntu experience required for coredev as his contributions list on this page is showing.

To share one example of non trivial package update I sponsored for him
https://launchpad.net/ubuntu/+source/strace/6.19+ds-0ubuntu1

That’s the update of strace to an new upstream version with the addition of distro patches to fixes the build in the new Ubuntu series + some improvements.

The work he did on that one was solid and it didn’t needed any change to be uploaded.

1 Like
5

My endorsement for JJ’s core-dev application is heavily based on my former endorsement for his server packageset application in Application - Server package set - Jonas Jelten - #5 by athos-ribeiro .

Sponsoring feedback

JJ always looks for the best solution for each single problem he decides to tackle. He is never afraid of pointing issues in less efficient processes, and always proposes better solutions or improvements for those. I hereby endorse his application for Ubuntu Core Developer.

Specific experiences of working together

JJ works with me in the Ubuntu server team. He is an experienced engineer with great knowledge on low-level stuff. His “automate everything” mentality is a strong point which benefits and will keep benefiting Ubuntu in the long run.

Areas of improvement

There is nothing specific to point here. It would be nice to see more volume on different areas of the distro (e.g., transitions). However, I also agree with Paride on letting JJ use his time to keep the great work on improving our tooling.

1 Like