docker-regclient

A small utility for listing and deleting images in a Docker registry. Can be invoked from cron to periodically cleanup images from a Docker registry.

Usage

NAME:
   docker-regclient - A small utility for listing and deleting images from a Docker registry

USAGE:
   docker-regclient [global options] command [command options] [arguments...]

VERSION:
   1.0.2

COMMANDS:
     repos    Display a list of repositories in the registry
     images   Display images (and possibly delete) from specified repositories
     delete   Reads lines containing repository:tag from STDIN and deletes the respective images from the Registry
     help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS:
   --url value, -u value  The URL of your Docker Registry
   --verify-tls, -k       Verify the TLS cetificate of the registry
   --help, -h             show help
   --version, -v          print the version

Example

Imagine that you have a Docker registry containing images in two repositories

webserver:devbuild-5
webserver:devbuild-4
webserver:rc3
webserver:devbuild-3
webserver:devbuild-2
webserver:devbuild-1
webserver:rc2
.....

backend-server:dev-56
backend-server:dev-55
backend-server:dev-54
backend-server:dev-53
.....

You could use the following command line to delete all but the latest three images from the webserver and backend-server repositories that have a tag containing the string dev.

docker-regclient -url https://my.docker.registry \
    images \
    --repo webserver \
    --repo backend-server \
    --exclude-latest 3 \
    --tag-contains dev \
    --delete \
    --yes

This is useful when you have some CI system that automatically builds and pushes new Docker images into your registry and you only want to keep the latest n images.

Reclaiming space

This utility only works against the API of a Docker registry and marks the images to be deleted. In order to actually claim the storage space under the deleted images, you will have to force the registry to garbage collect. In case you use the official registry image:

docker exec -ti registry-container /bin/registry garbage-collect /etc/docker/registry/config.yml

Building locally

• Install Go
• go get github.com/loginoff/docker-regclient

Disclaimer

Use at your own peril. In case you manage to somehow destroy all data in your registry using this code, the author can in no way be held responsible.