Install umoci with Homebrew, apk, apt, dnf, Nix, pacman, zypper

Project links

• Homepage
• Repository
• Upstream docs
• Package manager page

Commands and aliases

• umoci

Project history

The official documentation gives umoci a clear origin story: it was originally developed in 2016 by Aleksa Sarai as part of the openSUSE project. Its name expands to 'Umoci Modifies Open Containers' Images', and the project describes itself as a small, unopinionated reference implementation of the OCI image specification.

In mid-2020, umoci was donated to the Open Container Initiative as a reference implementation of the OCI image specification. The 0.4.6 changelog records the adoption and the corresponding import-path/module move from github.com/openSUSE/umoci to github.com/opencontainers/umoci.

The project retained its role as infrastructure rather than an end-user container runtime. The README and docs emphasize that umoci is meant to be a foundation for larger systems, while its Go API is useful but historically treated cautiously because it was not promised as stable.

Adoption history

The OCI adoption made umoci part of the official container-image standards ecosystem. The project documentation explicitly says the adoption solidified it as useful 'boring container infrastructure' for larger systems.

The Homebrew input shows broad downstream packaging across apk, Homebrew, Debian/Ubuntu source packages, dnf, Nix, pacman, and zypper. That distribution pattern matches the tool's role: a specialized container-image utility useful to build systems, distro packaging, rootless-container workflows, and OCI conformance work.

How it is used

umoci is used from a subcommand-based CLI for OCI image operations such as getting an image, unpacking, modifying, repacking, garbage collection, rootless workflows, and reference operations documented in generated man pages.

For package-focused users, the appeal is that umoci manipulates OCI image layouts directly without requiring a full Docker-style daemon. That makes it useful in scripts, package build pipelines, distro tooling, and low-level debugging of container-image contents.

Why package nerds care

umoci is significant in the package-nerd niche because it sits at the boundary between package building and container image building: it is small enough to install as a CLI, official enough to be under the Open Containers organization, and low-level enough for reproducible or rootless image workflows.

Its 2020 move from openSUSE to Open Containers is especially important for provenance: package maintainers had to track the import-path change, while users gained an OCI-hosted reference implementation.

Timeline

• 2016: umoci originally developed by Aleksa Sarai as part of openSUSE.
• 2020-06-24: umoci 0.4.6 changelog announces adoption by the Open Container Initiative and import-path move to github.com/opencontainers/umoci.
• 2021-04-05: umoci 0.4.7 fixes CVE-2021-29136 in unpack/raw unpack behavior.
• 2025: Release notes for 0.6.0 describe support for OCI image-spec v1.1.1 reading features and OCI runtime-spec v1.2.1 config generation.

Related projects

• Related standards and projects include the OCI image specification, OCI runtime specification, openSUSE, Open Container Initiative governance, and larger systems built on top of OCI image layouts.

Sources

• https://github.com/opencontainers/umoci
• https://github.com/opencontainers/umoci/releases
• https://umo.ci/
• https://umo.ci/meta/changelog/
• source_facts.package-manager