docker system prune Command Reference

Remove unused Docker data to reclaim disk.

docker system prune removes stopped containers, unused networks, dangling images, and dangling build cache. With -a it also removes all unused (not just dangling) images, and --volumes adds anonymous volumes. It is the go-to fix for "no space left on device".

Common flags

-a, --all - remove all unused images, not only dangling ones
-f, --force - do not prompt for confirmation
--volumes - also remove unused anonymous volumes
--filter - limit by condition, e.g. until=24h

Example

shell

docker system prune -af
docker system prune -af --volumes --filter "until=24h"

In CI

Run docker system prune -af when a build fails with "no space left on device" on a long-lived runner, or proactively at job start. Be careful with -a: it removes images not used by a running container, including ones you may rely on for the next step. Ephemeral runners rarely need this since the disk is discarded after the job.

Key takeaways

-af force-removes all unused images plus stopped containers, networks, and dangling cache.
--volumes additionally clears anonymous volumes.
It is the standard remedy for "no space left on device" on persistent runners.