local cache: add lazy option to skip eager extraction on import#6573
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jirimoravcik wants to merge 1 commit intomoby:masterfrom
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local cache: add lazy option to skip eager extraction on import#6573jirimoravcik wants to merge 1 commit intomoby:masterfrom
jirimoravcik wants to merge 1 commit intomoby:masterfrom
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Pull request overview
This PR introduces an opt-in lazy=true mode for --import-cache type=local to avoid eager “unlazying” (layer extraction) during cache import, improving rebuild performance for ephemeral/daemonless buildkitd setups.
Changes:
- Add
lazyattribute parsing to the local cache importer and use it to skipunlazyProviderwrapping. - Document the new
lazyoption in thebuildctlreference and repository README. - Update
getContentStoreto optionally return the raw session-backed content store when lazy mode is enabled.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| docs/reference/buildctl.md | Documents --import-cache type=local,...,lazy=true usage for buildctl. |
| cache/remotecache/local/local.go | Implements lazy attribute to bypass eager unlazying by skipping unlazyProvider. |
| README.md | Adds lazy=<true|false> to local cache import option docs. |
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Add a lazy=true option to the local cache importer (--import-cache type=local,src=...,lazy=true) that skips the unlazyProvider wrapping. In ephemeral/daemonless buildkitd setups, this avoids eagerly extracting all cached layers on every build. Signed-off-by: Jiří Moravčík <jiri.moravcik@gmail.com>
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When using
--import-cache type=localwith an ephemeral/daemonlessbuildkitd(one container per build), every build eagerly extracts all base image layers from the local cache — even when those layers are CACHED and don't need re-execution.With a large base image like
node:20(~350MB, 8 layers), this adds 5–10 seconds to what should be a near-instant rebuild. I've thoroughly described this in #6572.This PR fixes it by introducing
lazyparam to the local cache. If it'sfalse- default, the behavior remains unchanged. If you set it totrue, it will not perform "unlazying" on the layers, which improves the performance.Closes #6572