oc-mirror

packaged by Chainguard

Chainguard Container for oc-mirror

Minimal image with oc-mirror, the OpenShift tool for mirroring container content to disconnected (air-gapped) environments.

Chainguard Containers are regularly-updated, secure-by-default container images.

Download this Container Image

For those with access, this container image is available on cgr.dev:

docker pull cgr.dev/ORGANIZATION/oc-mirror:latest

Be sure to replace the ORGANIZATION placeholder with the name used for your organization's private repository within the Chainguard Registry.

Compatibility Notes

Chainguard's oc-mirror image is comparable to Red Hat's oc-mirror-plugin-rhel9 image (registry.redhat.io/openshift4/oc-mirror-plugin-rhel9). Like Red Hat's image, it is published per OpenShift release, each built from that release's release-X.Y branch, and its entrypoint is /usr/bin/oc-mirror. The differences:

• The image runs as the nonroot user (UID 65532) instead of root.
• The working directory is /home/nonroot, so relative workspace and archive paths are writable.
• Only /usr/bin/oc-mirror is shipped. Red Hat's RHEL 8 and RHEL 9 binary copies are not included.
• The image has no shell, so sh -c wrappers do not work. Use the -dev variant if you need one.

In both images, the second engine is embedded in the binary and extracted to the system temp directory when used, so that directory must be writable and not mounted noexec; set TMPDIR to use another one. In 4.21 and later, every command except version needs --v2 or --v1; in 4.20, the v1 engine is the default and v2 runs with --v2.

Getting Started

oc-mirror reads an ImageSetConfiguration file. The examples use --v2, which works on every stream. Mount a directory for the configuration, the workspace, and the archive:

mkdir -p oc-mirror && chmod 0777 oc-mirror
cat > oc-mirror/isc.yaml <<'EOF'
kind: ImageSetConfiguration
apiVersion: mirror.openshift.io/v2alpha1
mirror:
  additionalImages:
    - name: cgr.dev/chainguard/static:latest
EOF

Mirror to disk. This writes mirror_000001.tar and the working directory to /work/archive:

docker run --rm -v "$PWD/oc-mirror:/work" cgr.dev/ORGANIZATION/oc-mirror:latest \
  --v2 -c /work/isc.yaml file:///work/archive

Then, from inside the disconnected environment, push the archive to a registry:

docker run --rm -v "$PWD/oc-mirror:/work" cgr.dev/ORGANIZATION/oc-mirror:latest \
  --v2 -c /work/isc.yaml --from file:///work/archive docker://registry.example.internal:5000

To copy directly from one registry to another, combine a workspace with a docker:// destination:

docker run --rm -v "$PWD/oc-mirror:/work" cgr.dev/ORGANIZATION/oc-mirror:latest \
  --v2 -c /work/isc.yaml --workspace file:///work/workspace docker://registry.example.internal:5000

Configuration

Registry credentials are read from the file passed with --authfile, or from REGISTRY_AUTH_FILE. Without either, oc-mirror uses ${XDG_RUNTIME_DIR}/containers/auth.json and falls back to the Docker config. Mount your pull secret and point oc-mirror at it:

docker run --rm -v "$PWD/oc-mirror:/work" -v "$HOME/pull-secret.json:/auth/pull-secret.json:ro" \
  cgr.dev/ORGANIZATION/oc-mirror:latest \
  --v2 -c /work/isc.yaml --authfile /auth/pull-secret.json file:///work/archive

Blobs are cached under $HOME/.oc-mirror/.cache (/home/nonroot/.oc-mirror/.cache in this image). Set OC_MIRROR_CACHE or --cache-dir to keep the cache on a mounted volume between runs.

Documentation and Resources

• oc-mirror on GitHub
• Image set configuration examples
• oc-mirror usage

What are Chainguard Containers?

Chainguard's free tier of Starter container images are built with Wolfi, our minimal Linux undistro.

All other Chainguard Containers are built with Chainguard OS, Chainguard's minimal Linux operating system designed to produce container images that meet the requirements of a more secure software supply chain.

The main features of Chainguard Containers include:

• Minimal design, without unnecessary software bloat
• Daily builds to ensure container images are up-to-date with available security patches
• High quality build-time SBOMs attesting to the provenance of all artifacts within the image
• Verifiable signatures provided by Sigstore
• Reproducible builds with Cosign and apko (read more about reproducibility)

For cases where you need container images with shells and package managers to build or debug, most Chainguard Containers come paired with a development, or -dev, variant.

In all other cases, including Chainguard Containers tagged as :latest or with a specific version number, the container images include only an open-source application and its runtime dependencies. These minimal container images typically do not contain a shell or package manager.

Although the -dev container image variants have similar security features as their more minimal versions, they include additional software that is typically not necessary in production environments. We recommend using multi-stage builds to copy artifacts from the -dev variant into a more minimal production image.

Need additional packages?

To improve security, Chainguard Containers include only essential dependencies. Need more packages? Chainguard customers can use Custom Assembly to add packages, either through the Console, chainctl, or API.

To use Custom Assembly in the Chainguard Console: navigate to the image you'd like to customize in your Organization's list of images, and click on the Customize image button at the top of the page.

Learn More

Refer to our Chainguard Containers documentation on Chainguard Academy. Chainguard also offers VMs and Libraries — contact us for access.

Trademarks

This software listing is packaged by Chainguard. The trademarks set forth in this offering are owned by their respective companies, and use of them does not imply any affiliation, sponsorship, or endorsement by such companies.