Harden GitHub Actions workflows - #83
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- suppress cache-poisoning on release setup-ruby (ref-isolated cache) - suppress unpinned-uses on ruby/actions reusable workflow (@master needed for a current Ruby version matrix)
Deny-all at the workflow level and grant each job only what it needs: lint-actions and test get contents:read; ruby-versions (reusable workflow) and ci-pass need none.
Neither the test job nor the release job needs the persisted checkout token: rubygems/release-gem configures its own git credential cache for the tag push (its README documents persist-credentials: false).
The single push job already declares its own contents:write and
id-token:write, so the workflow-level block can be permissions: {}.
CI runs zizmor v1.23.1, which flags the direct ${{ needs.test.result }}
expansion in the ci-pass run block as template-injection (newer zizmor no
longer does). Move the expression into an env var so the shell reads a plain
variable instead.
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This hardens the GitHub Actions workflows against the vulnerability classes that zizmor audits. It handles the cache-poisoning concern differently from #76, see thread in that PR.
Changes
lint-actionsjob inci.ymlruns actionlint and zizmor on every push and pull request, so workflow regressions surface in CI.github-actionsentries independabot.ymlgain a seven-day cooldown, which matches the minimum age used when pinning.pinact. Theruby/actionsruby_versions.ymlreusable workflow stays on@masterso that the Ruby version matrix remains current, and an inline comment records why that reference is not pinned.GITHUB_TOKENpermissions are scoped per job. Both workflows deny all permissions at the top level and grant each job only the permissions it needs.persist-credentials: false. The release job remains correct becauserubygems/release-gemconfigures its own git credential cache for the tag push.Cache poisoning in the release workflow
I kept
bundler-cache: trueinpush_gem.ymland suppressed the zizmorcache-poisoningfinding rather than disabling the cache. GitHub Actions caches are isolated by git ref. A cache created by a pull request lives in therefs/pull/<n>/mergescope and can only be restored by re-runs of that pull request, so nothing a fork or pull request does can reach the cache that this tag-push release build restores. The inline suppression comment records this reasoning.Verification
zizmor reports no findings under both the default and pedantic personas, and actionlint is clean.