Docker Cleanup

This image will periodically clean up exited containers and remove images and volumes that aren't in use by a running container. Based on tutumcloud/image-cleanup and chadoe/docker-cleanup-volumes with some small fixes.

Normally any Docker containers that exit are still kept on disk until docker rm -v is used to clean them up. Similarly any images that aren't used any more are kept around. For a cluster node that see lots of containers start and stop, large amounts of exited containers and old image versions can fill up the disk. A Jenkins build slave has the same issues, but can also suffer from SNAPSHOT images being continuously rebuilt and causing untagged images to be left around.

Environment Variables

The default parameters can be overridden by setting environment variables on the container using the docker run -e flag.

• CLEAN_PERIOD=1800 - Interval in seconds to sleep after completing a cleaning run. Defaults to 1800 seconds = 30 minutes.
• DELAY_TIME=1800 - Seconds to wait before removing exited containers and unused images. Defaults to 1800 seconds = 30 minutes.
• KEEP_IMAGES - List of images to avoid cleaning, e.g. "ubuntu:trusty, ubuntu:latest". Defaults to clean all unused images.
• KEEP_CONTAINERS - List of images for exited or dead containers to avoid cleaning, e.g. "ubuntu:trusty, ubuntu:latest".
• LOOP - Add the ability to do non-looped cleanups, run it once and exit. Options are true, false. Defaults to true to run it forever in loops.

Deployment

The image uses the Docker client to to list and remove containers and images. For this reason the Docker client and socket is mapped into the container.

If the /var/lib/docker directory is mapped into the container this script will also clean up orphaned Docker volumes.

Systemd and CoreOS/Fleet

Create a Systemd unit file in /etc/systemd/system/docker-cleanup.service with contents like below. Using CoreOS and Fleet then add the X-Fleet section to schedule the unit on all cluster nodes.

[Unit]
Description=Cleanup of exited containers and unused images/volumes
After=docker.service
Requires=docker.service

[Install]
WantedBy=multi-user.target

[Service]
Environment=IMAGE=meltwater/docker-cleanup:latest NAME=docker-cleanup

# Allow docker pull to take some time
TimeoutStartSec=600

# Restart on failures
KillMode=none
Restart=always
RestartSec=15

ExecStartPre=-/usr/bin/docker kill $NAME
ExecStartPre=-/usr/bin/docker rm $NAME
ExecStartPre=-/bin/sh -c 'if ! docker images | tr -s " " : | grep "^${IMAGE}:"; then docker pull "${IMAGE}"; fi'
ExecStart=/usr/bin/docker run \
    -v /var/run/docker.sock:/var/run/docker.sock:rw \
    -v /var/lib/docker:/var/lib/docker:rw \
    --name=${NAME} \
    $IMAGE

ExecStop=/usr/bin/docker stop $NAME

[X-Fleet]
Global=true

Puppet Hiera

Using the garethr-docker module

classes:
  - docker::run_instance

docker::run_instance:
  'cleanup':
    image: 'meltwater/docker-cleanup:latest'
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock:rw"
      - "/var/lib/docker:/var/lib/docker:rw"

Command Line

docker run \
  -v /var/run/docker.sock:/var/run/docker.sock:rw \
  -v /var/lib/docker:/var/lib/docker:rw \
  meltwater/docker-cleanup:latest

Development

A Makefile is included to help with repetitive commands during development.

make help