Docker registry cleaner

Docker registry side-car container. Designed to be run alongside with Registry container and clean unneeded tags and layers in periodic manner.

Cleaner runs on file system shared with Registry service. It search for tags to delete and then runs registry garbage-collect to purge orphaned layers.

Environment variables

Variable	Default value	Description
DRY_RUN	"true"	You have to explictly set DRY_RUN=false to actually delete tags
VOLUME	/var/lib/registry	Registry path
CONFIG	/etc/docker/registry/config.yml	Registry config.yml path
CLEAN_SCHEDULE	"0 1 * * 6"	Clean schedule, crontab format. Default is to run every Saturday at 01:00AM
REPOS_CLEAN_NEVER	""	Space separated list of repositories we should never cleanup. Each repo name can be expr-type regular expression. Example: REPOS_CLEAN_NEVER="public/.*-dotnet importantrepo .*/.*test"
TAGS_CLEAN_NEVER	"latest .*-latest v[.0-9]*"	Space separated list of tags we should never cleanup. Each tag name can be expr-type regular expression. Example: TAGS_CLEAN_NEVER="latest .*-latest v[.0-9]*"
TAGS_KEEP_N	10	How much images we should keep. This setting applies after TAGS_CLEAN_NEVER screening
TAGS_KEEP_SEC	0	Never delete images created less than TAGS_KEEP_SEC seconds. This setting applies after TAGS_KEEP_N screening

Kubernetes usage example

Add registry cleaner as sidecar to existing deployment:

cat > patch-docker-registry.yaml << EOF
spec:
  template:
    spec:
      containers:
      - name: registry-cleaner
        image: ghcr.io/baznikin/docker-registry-cleaner
        volumeMounts:
        - mountPath: /var/lib/registry/
          name: data
        - mountPath: /etc/docker/registry
          name: registry-docker-registry-config
          readOnly: true
        env:
        - name: DRY_RUN
          value: "false"
        - name: CLEAN_SCHEDULE
          value: "*/5 * * * *"
        - name: REGISTRY_STORAGE_FILESYSTEM_ROOTDIRECTORY
          value: /var/lib/registry
EOF
kubectl patch deployments.apps registry-docker-registry -p "$(cat patch-docker-registry.yaml)"

Acknowlegement

Inspired by blog post Automate Docker Registry Cleanup by Al-Waleed Shihadeh, some bits of scripts and logic used as well.