docker system df: See Where Docker Disk Goes

See how much disk images, containers, volumes, and build cache use.

docker system df reports Docker disk usage by category and how much is reclaimable. This page covers the verbose breakdown that tells you what to prune in CI.

What it does

docker system df summarizes disk used by images, containers, local volumes, and build cache, with a RECLAIMABLE column. -v expands each category to per-object detail so you can see the biggest offenders.

Common usage

Terminal

docker system df
docker system df -v                     # per-image / per-volume detail

Common errors in CI

When a runner hits "no space left on device", docker system df shows whether images, volumes, or build cache dominate - then prune the right category instead of wiping everything. A common surprise is a huge "Build Cache" RECLAIMABLE figure from BuildKit; clear it with docker builder prune. df itself is read-only and does not error in normal use.

Related guides

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