Minimal Private OCI Image Registry

A very simple registry yaml representing K8s objects, with additional following features:

• Multi-user auth support: read-only users, administrators
• Image deletion support & automatic garbage collection on image startup

Useful if you don't want to use external projects to manage your private registry, but supports minimal features for sharing with others.

Abstract Structure

Usage

Getting Started

• podman

  podman kube play mreg.yml

• k8s

  kubectl apply -f mreg.yml

Manage Users

By default, there is no user exist.
You should add users (and toggle some of them to admin) to use registry.

• Basic usages

  • podman

    podman exec -it mreg-pod-auth manage-user [args...]

  • k8s

    kubectl exec -it deploy/mreg -n mreg -- manage-user [args...]

• Argument details
  (Run commands inside a AUTH container, as 'Basic usages' above)

  • List users

    manage-user ls

  • Add a user

    manage-user add <user-name>

  • Toggle a user between user <=> admin

    manage-user toggle <user-name>

  • Delete a user

    manage-user rm <user-name>

• Remarks

  • Normal users: GET HEAD are allowed
  • Administrators: GET HEAD POST PUT DELETE PATCH are allowed

Manage TLS

When cert/key files are added, the pod will serve as https.

• Basic usages

  • podman

    podman exec -it mreg-pod-auth manage-tls [arg]

  • k8s

    kubectl exec -it deploy/mreg -n mreg -- manage-tls [arg]

• Argument details
  (Run commands inside a AUTH container, as 'Basic usages' above)

  • Print current TLS info

    manage-tls print

  • Write or delete cert file (tls.crt)

    manage-tls cert

  • Write or delete key file (tls.key)

    manage-tls key

• Remarks

  • You can create your own cert/key files yourself, or with the script script/mreg-gen-tls.

    script/mreg-gen-tls <address-to-access-registry>

  • It is possible to redirect STDIN when writing cert/key files:

    • podman

      podman exec -i mreg-pod-auth manage-tls cert < your-tls-file.crt
      podman exec -i mreg-pod-auth manage-tls key < your-tls-file.key

    • k8s

      kubectl exec -i deploy/mreg -n mreg -- manage-tls cert < your-tls-file.crt
      kubectl exec -i deploy/mreg -n mreg -- manage-tls key < your-tls-file.key

Untag Image Manifest Remotely

• Important Notes
  • Guide below deletes not only specified tag, but also all img:tags referencing the same manifest!
    • (e.g. If you push the same image with both a:latest & a:v1.1, then delete a:v1.1, then a:latest is also removed)
  • If you want to delete only the specified tag, push a dummy image to the target image:tag, then delete according to the following.
  • Or you might use external utility such as regctl, etc.

(Check script/mreg-manage for one-shot untag)

1. Get a digest of target image tag manifest

   # first set required variables for commands below:
   # ADMIN_ID="<id>" REG_ADDR="<registry-addr-port>" IMG_NAME="<img>" IMG_TAG="<tag>"
   
   DIGEST="$(curl -u "${ADMIN_ID:?}" \
     -H "Accept: application/vnd.oci.image.manifest.v1+json" \
     -I "${REG_ADDR:?}"/v2/"${IMG_NAME:?}"/manifests/"${IMG_TAG:?}" \
     | grep "^Docker-Content-Digest" \
   )"

2. Delete manifest (untag)
   Warning: This DELETE request will untag & delete ALL TAGS REFERENCING THE SAME TARGET DIGEST!

   curl -u "${ADMIN_ID:?}" -X DELETE \
     "${REG_ADDR:?}"/v2/"${IMG_NAME:?}"/manifests/"${DIGEST:?}"

Automatic Image Garbage Collection

(Delete unused blob which is untagged above)

• When minimal-oci-registry image starts, unused files are removed before registry starts up.
• Consider scheduling image restart periodically (every 5 AM, etc.) to garbage collect storage!

Author

Kim Hwiwon <kim.hwiwon@outlook.com>