Docker

Choose Use path routing as the routing mode of the Docker repositories (see reverse proxy). The repository name is the first part of the image name:

docker login astrum.example.com
docker pull astrum.example.com/docker-group/library/nginx:1.27
docker tag app:1.0 astrum.example.com/docker-hosted/team/app:1.0
docker push astrum.example.com/docker-hosted/team/app:1.0

podman, buildah, skopeo, crane and containerd use the same names. For anonymous pulls activate the Docker Bearer Token Realm and allow anonymous access.

OCI artifacts

Docker repositories implement the OCI Distribution Specification 1.1 and store any OCI artifact, not only container images: Helm charts, signatures, SBOMs, attestations, Wasm modules, AI models. Add --plain-http to oras and helm when the server is reached over plain HTTP.

helm registry login astrum.example.com
helm push mychart-1.2.0.tgz oci://astrum.example.com/docker-hosted/charts
helm install mychart oci://astrum.example.com/docker-group/charts/mychart --version 1.2.0

oras push astrum.example.com/docker-hosted/team/model:q4 \
  --artifact-type application/vnd.cncf.model.manifest.v1+json weights.gguf:application/vnd.cncf.model.weight.v1.raw
oras attach --artifact-type application/spdx+json \
  astrum.example.com/docker-hosted/team/app:1.0 sbom.spdx.json:application/spdx+json
oras discover astrum.example.com/docker-group/team/app:1.0

cosign sign --key cosign.key astrum.example.com/docker-hosted/team/app@sha256:...
notation sign astrum.example.com/docker-hosted/team/app@sha256:...

Signatures, SBOMs and attestations attached through subject are listed by the referrers API (GET /v2/<name>/referrers/<digest>, filtered with ?artifactType=). A hosted repository also lists what a client kept under the tag of the referrers tag schema (sha256-<hex>). A proxy asks its remote, reads that tag when the remote has no referrers API, and keeps listing the referrers it has cached when the remote is down. A group lists the referrers of all its members. A mount from another Docker repository (from=<repository>/<name>) copies the blob when the user may read it there.

Search and the repository browser tell artifacts apart: docker.artifactKind is image, helm, signature, sbom, attestation, wasm, model or other.

What is attached to a manifest lives and dies with it. Deleting a manifest by its digest through the registry API deletes the manifests whose subject it is, recursively, the tags that point at it and the tags of the tag schema derived from its digest (sha256-<hex>, .sig, .att, .sbom). Deleting a tag deletes only the tag. Layers are not removed with the manifests; the task Docker - Delete unused manifests and images deletes the layers that no manifest refers to, and untagged manifests, once they are older than its deploy offset (24 hours by default).