domain: docker · 7 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Run 'docker buildx du' on the currently selected builder to list every BuildKit cache record with its ID, reclaimable flag, size, and last-access time, plus a summary of shared/private/reclaimable/total space.
Scope to a specific builder with 'docker buildx du --builder <name>' when you run multiple builders.
Use --format=table to add column headers, --format=pretty (or --verbose) for per-record detail including parents/layers/usage counts and mutable/shared state, or --format=json for newline-delimited JSON you can pipe through jq for programmatic disk-usage analysis.
Target records with --filter, using the same selector keys as prune (until, id, parents, description, inuse, mutable, immutable, shared, private, type).
Adjust the status-loading timeout with --timeout (default 20s) for large/remote builders.
Read the summary lines (Shared/Private/Reclaimable/Total) to decide how much space a prune would actually reclaim before running one.
Official docs: https://docs.docker.com/reference/cli/docker/buildx/du/
Known gotchas
An asterisk next to a record ID means the record is mutable: its size may change or another build may take ownership/commit to it, so re-running du can show different numbers.
An asterisk next to the size means the record is shared (typically with an image); pruning it removes only build-cache metadata while the image keeps its actual storage layers.
Records flagged RECLAIMABLE=false are actively in use and will NOT be deleted even by 'buildx du prune --all'.
Buildx du shows the default builder's cache by default; remote/other builders must be selected with --builder.
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