ProtectHome=read-only made the whole home read-only and only RUNNER_DIR was
punched back through, so forgejo-runner could not create $HOME/.cache and
disabled its cache server on every install. actions/cache was silently off on
every rig-installed Forgejo runner, evidenced by one error line in the journal
while `status` reported a healthy runner.
Both halves are required, and the obvious one-line version is WORSE than the
bug: a ReadWritePaths entry naming a path that does not exist makes systemd
refuse to start the unit at all — "Failed to set up mount namespacing", three
restart attempts, service down. Measured on a live runner before writing this.
So the directory is created at install, owned by the runner user like
RUNNER_DIR beside it, and the unit lists it. ProtectHome stays read-only: the
runner supervises job containers on this box's docker socket, and the cache is
not a reason to widen that.
Verified live from scratch: directory removed, unit removed, converge, then
zero cache-server errors and the two cache listeners bound.
Closes#135
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
