Docker disk usage

Images, stopped containers, volumes and build cache pile up on the server's disk until something runs out of space. docker system df shows what takes room and how much can be reclaimed.

How it works

Every build leaves layers and cache, every docker run without --rm leaves a stopped container, every container log grows. When the disk is full, builds fail, databases stop writing and containers crash. The RECLAIMABLE column shows what nothing uses.

What breaks

Pruning volumes deletes every volume no container refers to at that moment: remove a database container, prune the volumes, and its data is gone for good. Clean in order: stopped containers, dangling images, build cache, and volumes only after checking what they hold.

In a terminal

docker system df
docker container prune -f
docker image prune -f
docker builder prune -f

See it break, then fix it

Write the Dockerfile or the compose file, type the docker commands, and watch a simulated server run them through reboots, upgrades and traffic. Free to start.

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