ci: stop saving Go build cache outside of main#5345
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Co-authored-by: Isaac
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## Why `push.yml` saves many setup-go caches per run, but PR / merge_group / schedule saves are scoped to refs no other run can read. They still count against the 10 GB per-repo quota and evict main's caches via LRU, so most PRs miss the cache entirely. See the [GitHub Actions dependency-caching docs](https://docs.github.com/en/actions/reference/workflows-and-actions/dependency-caching) for the scope and eviction rules. ## What ### `setup-build-environment` composite The composite now manages the Go cache explicitly instead of relying on `setup-go`'s built-in caching. `setup-go` runs with `cache: false`. On `refs/heads/main` (push + the scheduled wipe-and-repopulate cron from #2092) the unified `actions/cache@v5.0.5` restores immediately and its post-step saves at the calling job's end — composite-action post-steps fire at the job's end, not the composite's, so this works inside the composite. On every other ref, `actions/cache/restore@v5.0.5` restores only. `restore-keys` provides prefix fallback so PR runs with a changed `go.sum` still restore main's most recent cache and rebuild only the delta. The `cache.txt` workaround is gone — `inputs.cache-key` goes directly into the cache key string. ### Drop `task cover` from CI `task cover` was a smoke check on main pushes. Cover-instrumented test binaries land in a different `GOCACHE` slot than the non-cover binaries PRs need, so a `go.sum` bump landing on a main push would leave the cache holding cover artifacts until the next 00:00 UTC wipe-and-repopulate fixed it (up to 24h of PRs missing the test-binary slot). Running `task test` on every event eliminates that hole; coverage stays in `Taskfile.yml` for local use and can come back to CI when there's a real consumer. ### Scheduled cache wipe: twice daily → once daily The cron from #2092 wiped the cache at 00:00 and 12:00 UTC. The noon wipe was harmless when every PR repopulated; now that only main runs repopulate, it creates an unnecessary cold-cache window during the workday. Trimmed to 00:00 UTC. ## Potential follow-ups - `check.yml` lint cache - Three standalone `setup-go` invocations in `push.yml` (`testmask`, `validate-generated-is-up-to-date`, `validate-python-codegen`) - `~/.cache/golangci-lint` analyzer cache This pull request and its description were written by Isaac.
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Why
push.ymlsaves many setup-go caches per run, but PR / merge_group / schedule saves are scoped to refs no other run can read. They still count against the 10 GB per-repo quota and evict main's caches via LRU, so most PRs miss the cache entirely.See the GitHub Actions dependency-caching docs for the scope and eviction rules.
What
setup-build-environmentcompositeThe composite now manages the Go cache explicitly instead of relying on
setup-go's built-in caching.setup-goruns withcache: false. Onrefs/heads/main(push + the scheduled wipe-and-repopulate cron from #2092) the unifiedactions/cache@v5.0.5restores immediately and its post-step saves at the calling job's end — composite-action post-steps fire at the job's end, not the composite's, so this works inside the composite. On every other ref,actions/cache/restore@v5.0.5restores only.restore-keysprovides prefix fallback so PR runs with a changedgo.sumstill restore main's most recent cache and rebuild only the delta. Thecache.txtworkaround is gone —inputs.cache-keygoes directly into the cache key string.Drop
task coverfrom CItask coverwas a smoke check on main pushes. Cover-instrumented test binaries land in a differentGOCACHEslot than the non-cover binaries PRs need, so ago.sumbump landing on a main push would leave the cache holding cover artifacts until the next 00:00 UTC wipe-and-repopulate fixed it (up to 24h of PRs missing the test-binary slot). Runningtask teston every event eliminates that hole; coverage stays inTaskfile.ymlfor local use and can come back to CI when there's a real consumer.Scheduled cache wipe: twice daily → once daily
The cron from #2092 wiped the cache at 00:00 and 12:00 UTC. The noon wipe was harmless when every PR repopulated; now that only main runs repopulate, it creates an unnecessary cold-cache window during the workday. Trimmed to 00:00 UTC.
Potential follow-ups
check.ymllint cachesetup-goinvocations inpush.yml(testmask,validate-generated-is-up-to-date,validate-python-codegen)~/.cache/golangci-lintanalyzer cacheThis pull request and its description were written by Isaac.