Adds an opt-in goroutine that polls GHCR every 5 minutes for digest
changes on each workspace-template-*:latest tag and invokes the same
refresh logic /admin/workspace-images/refresh exposes. With this, the
chain from "merge runtime PR" to "containers running new code" is fully
hands-off — no operator step between auto-tag → publish-runtime →
cascade → template image rebuild → host pull + recreate.
Opt-in via IMAGE_AUTO_REFRESH=true. SaaS deploys whose pipeline already
pulls every release should leave it off (would be redundant work);
self-hosters get true zero-touch.
Why a refactor of admin_workspace_images.go is in this PR:
The HTTP handler held all the refresh logic inline. To share it with
the new watcher without HTTP loopback, extracted WorkspaceImageService
with a Refresh(ctx, runtimes, recreate) (RefreshResult, error) shape.
HTTP handler is now a thin wrapper; behavior is preserved (same JSON
response, same 500-on-list-failure, same per-runtime soft-fail).
Watcher design notes:
- Last-observed digest tracked in memory (not persisted). On boot the
first observation per runtime is seed-only — no spurious refresh
fires on every restart.
- On Refresh error, the seen digest rolls back so the next tick retries.
Without this rollback a transient Docker glitch would convince the
watcher the work was done.
- Per-runtime fetch errors don't block other runtimes (one template's
brief 500 doesn't pause the others).
- digestFetcher injection seam in tick() lets unit tests cover all
bookkeeping branches without standing up an httptest GHCR server.
Verified live: probed GHCR's /token + manifest HEAD against
workspace-template-claude-code; got HTTP 200 + a real
Docker-Content-Digest. Same calls the watcher makes.
Co-authored-by: Hongming Wang <hongmingwangalt@gmail.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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