[KavanPrice]

Summary

Release builds never used the Docker layer cache. It was kept in the GitHub Actions cache, which a release can't read back because each release runs on its own tag, so every image was built from scratch. In v6.13.1 only 1 of 46 image builds had a cache hit.

• Build caches now live in GHCR next to each image, as <image>:buildcache (or buildcache-<arch>).
• krb-keys-operator copies only lib/py-python-kadmv, so changes elsewhere in lib/ no longer rerun its 3-5 minute pip compile, the slowest step of every release.
• ARG revision/tag is declared just above the step that writes the version, so npm install can come from cache. This also fixes the empty GIT_VERSION in acs-cmdesc, acs-auth and acs-data-access.
• Cached layers no longer pick up new Alpine packages or unpinned pip versions on every release. They refresh when their inputs or base image change.

[AlexGodbehere]

🔥

[KavanPrice]

Build time test

I published two pre-releases from this branch, both on the same commit (4acd86bf). v6.14.0-dev.1 started with no registry cache and filled it. v6.14.0-dev.2 then ran against that cache.

	Wall time	Runner time	Slowest job	Build steps from cache
v6.13.1	388s	3,844s	krb-keys-operator 317s	–
v6.14.0-rc.1	379s	3,970s	krb-keys-operator 278s	4/406
v6.14.0-dev.1 (cold cache)	419s	3,467s	krb-keys-operator 312s	0/406
v6.14.0-dev.2 (warm cache)	254s	2,472s	acs-admin 89s	300/406

• A release with a warm cache takes about a third less time, and runner time drops by about 37%.
• krb-keys-operator went from about 300s to 36s. Its pip compile of krb5/gssapi now comes from the cache.
• All 46 builds wrote their cache to GHCR. The only errors in dev.1 were the expected "not found" when importing a cache that didn't exist yet.
• Even the cold run used less runner time than before, because pushing the cache to GHCR is cheaper than uploading it to the Actions cache.
• dev.2 is the best case, because nothing changed between the two runs. In a real release, each service whose code changed also rebuilds from COPY . . onwards.