How to automatically remove docker images that are not associated to a container daily

Note: This will not only remove docker images without a tag but all docker images not associated to a running or stopped container. See our previous post How to automatically cleanup (prune) docker images daily in case this is not the desired behaviour. docker image prune provides an easy way to remove “unused” docker images from a system and hence fixes or significantly delays docker eating up all your disk space on e.g. automated disk space.

I created a systemd-timer based daily image removal routine using TechOverflow’s Simple systemd timer generator.

Quick install using

wget -qO- https://techoverflow.net/scripts/install-cleanup-docker-all.sh | sudo bash

This is the script which automatically creates & installs both systemd config files.

#!/bin/sh
# This script installs automated docker cleanup.
# onto systemd-based systems.
# See https://techoverflow.net/2020/02/04/how-to-remove-all-docker-images-that-are-not-associated-to-a-container/
# for details on what images are removed.
# It requires that docker is installed properly

cat >/etc/systemd/system/PruneDockerAll.service <<EOF
[Unit]
Description=PruneDockerAll

[Service]
Type=oneshot
ExecStart=/bin/bash -c "docker image ls --format '{{.ID}}' | xargs docker image rm ; true"
WorkingDirectory=/tmp
EOF

cat >/etc/systemd/system/PruneDockerAll.timer <<EOF
[Unit]
Description=PruneDockerAll

[Timer]
OnCalendar=daily
Persistent=true

[Install]
WantedBy=timers.target
EOF

# Enable and start service
systemctl enable PruneDockerAll.timer && sudo systemctl start PruneDockerAll.timer

To view the logs, use

journalctl -xfu PruneDockerAll.service

To view the status, use

sudo systemctl status PruneDockerAll.timer

To immediately cleanup your docker images, use

sudo systemctl start PruneDockerAll.service