regclient

Client interface for the registry API. This includes regctl for a command line interface to manage registries.

regclient Features

• Provides a client interface to interacting with registries.
• Images may be inspected without pulling the layers, allowing quick access to the image manifest and configuration.
• Tags may be listed for a repository.
• Repositories may be listed from a registry (if supported).
• Copying an image only pulls layers when needed, allowing images to be quickly retagged or promoted across repositories.
• Multi-platform images are supported, allowing all platforms to be copied between registries.
• Digest tags used by projects like sigstore/cosign are supported, allowing signature, attestation, and SBOM metadata to be copied with the image.
• Digests may be queried for a tag without pulling the manifest.
• Rate limits may be queried from the registry without pulling an image (useful for Docker Hub).
• Images may be imported and exported to both OCI and Docker formatted tar files.
• OCI Layout is supported for copying images to and from a local directory.
• Delete APIs have been provided for tags, manifests, and blobs (the tag deletion will only delete a single tag even if multiple tags point to the same digest).
• Registry logins are imported from docker when available
• Self signed, insecure, and http-only registries are all supported.
• Requests will retry and fall back to chunked uploads when network issues are encountered.

regctl Features

regctl is a CLI interface to the regclient library. In addition to the features listed for regclient, regctl adds the following abilities:

• Formatting output with templates.
• Push and pull arbitrary artifacts.

regsync features

regsync is an image mirroring tool. It will copy images between two locations with the following additional features:

• Uses a yaml configuration.
• The regclient copy is used to only pull needed layers, supporting multi-platform, and additional metadata.
• Can use user's docker configuration for registry credentials.
• Ability to run on a cron schedule, one time synchronization, or only check for stale images.
• Ability to backup previous target image before overwriting.
• Ability to postpone mirror step when rate limit is below a threshold.
• Ability to mirror multiple images concurrently.

regbot features

regbot is a scripting tool on top of the regclient API with the following features:

• Runs user provided scripts based on a yaml configuration.
• Scripts are written in Lua and executed directly in Go.
• Can run on a cron schedule or a one time execution.
• Dry-run option can be used for testing.
• Built-in functions include:
  • Repository list
  • Tag list
  • Image manifest (either head or get, and optional resolving multi-platform reference)
  • Image config (this includes the creation time, labels, and other details shown in a docker image inspect)
  • Image ratelimit and a wait function to delay the script when ratelimit remaining is below a threshold
  • Image copy
  • Manifest delete
  • Tag delete

Development Status

This project is in active development. Various Go APIs may change, but efforts will be made to provide aliases and stubs for any removed API.

Building

git clone https://github.com/regclient/regclient.git
cd regclient
make

Downloading Binaries

Binaries are available on the releases page.

The latest release can be downloaded using curl (adjust "regctl" and "linux-amd64" for the desired command and your own platform):

curl -L https://github.com/regclient/regclient/releases/latest/download/regctl-linux-amd64 >regctl
chmod 755 regctl

Merges into the main branch also have binaries available as artifacts within GitHub Actions

Running as a Container

You can run regctl, regsync, and regbot in a container.

For regctl (include a -t for any commands that require a tty, e.g. registry login):

docker container run -i --rm --net host \
  -v regctl-conf:/home/appuser/.regctl/ \
  regclient/regctl:latest --help

For regsync:

docker container run -i --rm --net host \
  -v "$(pwd)/regsync.yml:/home/appuser/regsync.yml" \
  regclient/regsync:latest -c /home/appuser/regsync.yml check

For regbot:

docker container run -i --rm --net host \
  -v "$(pwd)/regbot.yml:/home/appuser/regbot.yml" \
  regclient/regbot:latest -c /home/appuser/regbot.yml once --dry-run

Or on Linux and Mac environments, you can run regctl as your own user and save configuration settings, use docker credentials, and use any docker certs:

docker container run -i --rm --net host \
  -u "$(id -u):$(id -g)" -e HOME -v $HOME:$HOME \
  -v /etc/docker/certs.d:/etc/docker/certs.d:ro \
  regclient/regctl:latest --help

And regctl can be packaged as a shell script with:

cat >regctl <<EOF
#!/bin/sh
opts=""
case "\$*" in
  "registry login"*) opts="-t";;
esac
docker container run \$opts -i --rm --net host \\
  -u "\$(id -u):\$(id -g)" -e HOME -v \$HOME:\$HOME \\
  -v /etc/docker/certs.d:/etc/docker/certs.d:ro \\
  regclient/regctl:latest "\$@"
EOF
chmod 755 regctl
./regctl --help

Images are also included with an alpine base, which are useful for CI pipelines that expect the container to include a /bin/sh. These alpine based images also include the ecr-login and gcr credential helpers.

Installing as a Docker CLI Plugin

To install regctl as a docker CLI plugin:

make plugin-user # install for the current user
make plugin-host # install for all users on the host (requires sudo)

Once installed as a plugin, you can access it from the docker CLI:

$ docker regctl --help
Utility for accessing docker registries
More details at https://github.com/regclient/regclient

Usage:
  regctl <cmd> [flags]
  regctl [command]

Available Commands:
  help        Help about any command
  image       manage images
  layer       manage image layers/blobs
  registry    manage registries
  tag         manage tags
...

Usage

See the project documentation.