regview

View the contents of a Docker Registry v2

Docker image available at ghcr.io/ricardobranco777/regview:latest

Usage

regview [OPTIONS] REGISTRY[/REPOSITORY[:TAG|@DIGEST]]
  -a, --all                 Print information for all architecture
      --arch strings        Target architecture. May be specified multiple times
      --debug               Enable debug
      --delete              Delete images. USE WITH CAUTION
      --digests             Show digests
      --dry-run             Used with --delete: only show the images that would be deleted
  -f, --format string       Output format
      --insecure            Allow insecure server connections
      --no-trunc            Don't truncate output
      --os strings          Target OS. May be specified multiple times
  -p, --pass string         Password for authentication
      --raw                 Raw values for date and size
  -C, --tlscacert string    Trust certs signed only by this CA
  -c, --tlscert string      Path to TLS certificate file
  -k, --tlskey string       Path to TLS key file
  -P, --tlskeypass string   Passphrase for TLS key file
  -u, --user string         Username for authentication
  -v, --verbose             Show more information
      --version             Show version and exit
Valid options for --arch: 386 amd64 arm arm64 mips mips64 mips64le mipsle ppc64 ppc64le riscv64 s390x wasm
Valid options for --os: aix android darwin dragonfly freebsd illumos ios js linux netbsd openbsd plan9 solaris windows

Notes

• Shell pattern matching is supported in repositories and tags like busybo?/late* or debian:[7-9]

Supported authentication methods

• HTTP Basic Authentication
• Token Authentication

Supported registries

• Docker Distribution
• Amazon ECR (get credentials with aws ecr get-login and run docker login)
• Azure ACR (get credentials with az acr credential show -n $ and run docker login)
• Google GCR (run gcloud auth configure-docker and use [ZONE.]gcr.io/<PROJECT>/* to list the registry)

Deleting images

To delete tagged images you can use the --delete option. Use the --dry-run option is you want to view the images that would be deleted.

Steps:

1. Make sure that the registry container has the REGISTRY_STORAGE_DELETE_ENABLED environment variable (or the relevant entry in /etc/docker/registry/config.yml) set to true.
2. Run regview --delete ...
3. Either stop or restart the registry cointainer in maintenance mode by setting the REGISTRY_STORAGE_MAINTENANCE_READONLY environment variable to true (or editing the relevant entry in /etc/docker/registry/config.yml).
4. Run docker run --rm --volumes-from $CONTAINER registry:2 garbage-collect /etc/docker/registry/config.yml if the container was stopped. Otherwise docker exec $CONTAINER garbage-collect /etc/docker/registry/config.yml if the container is in maintenance mode.
5. Optionally run the same command from above appending --delete-untagged to delete untagged images.
6. Restart the registry container in production mode.

NOTES:

• The --delete-untagged option was added to Docker Registry 2.7.0
• The --delete-untagged option is BUGGY with multi-arch images. The only workaround is to push those images adding the os/arch name to the image name.
• USE AT YOUR OWN RISK!

BUGS / LIMITATIONS

• Listing a pull through cache Registry may pollute the cache with unwanted images as the cache proxies requests, ending up with TOOMANYREQUESTS error: "You have reached your pull rate limit. You may increase the limit by authenticating and upgrading: https://www.docker.com/increase-rate-limit".
• When developing this tool I was warned that I was DDOS'ing the production registry, so be careful when tweaking the code that uses goroutines.