Install GNU tar in the CI image so actions/cache works

actions/cache shells out to `tar --posix -P`. Alpine's busybox tar rejects both flags, so the cache step would fail in every job that runs inside these images — which is all of them once ci.yml switches over. coreutils does not cover this: tar is its own Alpine package. Add it, add zstd (which actions/cache prefers over gzip when present), and assert GNU tar in the image's smoke test so a future base-image change cannot quietly drop it again. Part of #187 Co-Authored-By: Claude Opus 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01D9acV1mHktGAb1uyvNmrR2
2026-08-24 22:15:40 -03:00
parent e097b7a0bf
commit 28f586d207
2 changed files with 14 additions and 4 deletions
@@ -30,8 +30,12 @@ inside the cluster replaces the whole thing (#187).
  (`actions/checkout`, `actions/cache`, `actions/upload-artifact`) *inside*
  the job container and shells `run:` steps through bash. Without these, the
  first step of every job fails.
- **`coreutils`, `gawk`, `grep`, `sed`** — GNU versions, because the workflow
-  scripts use `tac` and `grep --include`, which busybox does not provide.
+- **`coreutils`, `gawk`, `grep`, `sed`, `tar`** — GNU versions, because the
+  workflow scripts use `tac` and `grep --include`, which busybox does not
+  provide. GNU `tar` matters most: `actions/cache` shells out to
+  `tar --posix -P`, and busybox rejects those flags, so every cache step fails
+  without it. `zstd` is what `actions/cache` reaches for over gzip when it is
+  installed.
 - **`curl`, `jq`, `git`, `zip`, `unzip`** — used by `release.yml` and
  `bin/build-zip.sh`.
 - **`intl` and `zip` PHP extensions**, plus Composer 2. `mbstring` is already