Aleksa Sarai
Founding Engineer at Amutable
Australia
Summary
🤩
Rockstar🎓
Top SchoolAleksa Sarai is a founding engineer and seasoned systems developer with 13 years of experience designing secure, deterministic Linux systems and container infrastructure. Based in Australia, he has led container core work at SUSE and spearheaded umoci, which was adopted by the Open Container Initiative as the reference implementation of the image spec. His contributions span kernel features (openat2, pids cgroup), container runtimes (runc, containerd, cri-o) and tooling (buildkit, skopeo), blending low-level OS work with reliable build and image tooling. Aleksa is an active OCI Technical Oversight Board member and long-term openSUSE maintainer, with a track record of fixing security-critical issues and improving reproducible builds. He also contributes in Rust and Go ecosystems (cbindgen, printpdf, libpathrs) and has a curious cross-cultural side—studying Japanese and originally from Pančevo—reflecting a practical, global perspective.
13 years of coding experience
10 years of employment as a software developer
The University of Sydney
English, Serbian, Japanese
Stackoverflow
2,870reputation
193kreached
48answers
2questions
gcc
top-5%
optimization
top-1%
Github Skills (90)
epub10
json-schema10
ebook-reader10
builder-pattern10
testing10
plugin-development10
c1110
security10
c1710
lua10
j10
runc10
svg10
build-automation10
pdf-generation10
Programming languages (27)
Github contributions (5)
opencontainers/umoci
Oct 2016 - Sep 2022
umoci modifies Open Container images
Role in this project:
Back-end Developer
Back-end DeveloperContributions:20 releases, 138 reviews, 765 commits in 6 years
Contributions summary:Aleksa's commits primarily revolve around implementing and improving the `umoci` tool, with a focus on modifying and generating OCI image layers. They have been active in reimplementing unpacking functionality, addressing issues related to whiteouts and hardlinks, and enhancing the tool's user experience by adding features such as ID mapping and bundle metadata management. The user's contributions include implementing a new "raw" mode for specific image manipulation tasks and adding options for the `--[ug]id-map` and `--no-history` flags, indicating a focus on usability, correctness, and improved performance.
containersoci-imagedocker-imagerootless-containersdocker
opencontainers/runc
Jun 2015 - Nov 2022
CLI tool for spawning and running containers according to the OCI specification
Role in this project:Back-end Developer
Back-end DeveloperContributions:43 releases, 948 reviews, 438 commits in 7 years 5 months
Contributions summary:Aleksa primarily contributed to the core functionality and API of the runc container runtime. They made significant improvements to the user namespace handling, including correctly setting up ID mappings within the container's context. The user also made improvements to the devices cgroup including adding the support for per-device weight, refactored the code and also added support for handling the memory limits. The changes demonstrate a focus on improving the stability, security, and functionality of the runc runtime.
containersruncseccompspecificationpodman
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