Clean Up Docker: Free Disk Space Safely

Docker quietly fills your disk with old images, stopped containers and build cache. The prune commands clean this up without shell tricks like docker rm $(docker ps -aq).

1. See what's using space

docker system df

Add -v for a breakdown per image, container and volume.

2. Clean up step by step

# Stopped containers
docker container prune

# Dangling images (untagged layers left over from builds)
docker image prune

# All images not used by any container – more aggressive
docker image prune -a

# Build cache (often the biggest item on build machines)
docker builder prune

# Unused volumes
docker volume prune

Note on volumes: since Docker Engine 23, docker volume prune only removes anonymous volumes. Add --all to include named volumes – and double-check first, because volumes contain data such as databases.

3. Everything at once

# Stopped containers, unused networks, dangling images, build cache
docker system prune

# Additionally: all unused images and anonymous volumes
docker system prune -a --volumes

Keep recent items

On CI runners or dev machines it's useful to only remove older data:

docker image prune -a --filter "until=168h"   # older than 7 days
docker builder prune --filter "until=24h"

Safety notes

• All prune commands ask for confirmation. -f skips it – use that only in scripts you trust.
• Removing images means they have to be pulled or built again next time.
• Never prune volumes on a server without knowing what's in them.