The unit has NoNewPrivileges=true (security hardening for srcds), which
blocks sudo's setuid escalation. The previous sudo'd ExecStartPre failed
on every start with "sudo: the 'no new privileges' switch is set, which
prevents sudo from running as root" -> Restart=on-failure loop.
systemd's `+` prefix runs the Exec command as PID 1 (root, no sandbox),
bypassing User=/Group=/NoNewPrivileges=. Equivalent privilege scope to
the sudoers rule the web app already uses for the same helper, just
without the sudo middleman.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Before this change there were two callers of left4me-overlay mount:
the web app's start_instance (Python, in-process) and the unit's
ExecStartPre (shell, via sudo). The duplication invited divergence; the
helper's recently-added idempotency made both paths technically work
but at the cost of a "first wins" race and dead-code retry logic in
start_instance.
Drop the in-process _mounter.mount() call from start_instance. The web
app now only stages cfg files (which still must happen on the host
filesystem before mount, to avoid overlayfs copy-up changing ownership),
then asks systemd to enable+start the unit; the unit's ExecStartPre
does the mount.
Removed:
- os.path.ismount(merged) refusal in start_instance and its test
(test_start_refuses_to_double_mount). The race the check guarded
against is now handled by the helper's idempotency.
- _load_instance_env helper and the `os` import (both became dead).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
systemd applies WorkingDirectory= to every Exec line including ExecStartPre.
With the merged dir not yet existing at boot time (the volatile overlay
mount has been wiped), the chdir into runtime/%i/merged/left4dead2 fails
with status=200/CHDIR before ExecStartPre can run the mount helper.
The `-` prefix makes chdir failure non-fatal: ExecStartPre runs in the
unit's home (cwd doesn't matter for the mount helper); ExecStart re-applies
WorkingDirectory once the mount has landed and chdirs successfully.
Companion to commit 519567e (which added the ExecStartPre mount + helper
idempotency but didn't account for the WorkingDirectory ordering).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
The lifecycle change to systemctl enable --now (commit 8552c55) made
units auto-start at boot. But the kernel-overlayfs mount is volatile
(reboot kills it), and the web app's start_instance only re-mounts in
response to a UI click. Result: at boot, systemd starts the unit, finds
empty merged/, CHDIR fails, Restart=on-failure spins forever (counter
hit 65 on ckn before this fix landed).
Fix:
- Unit gets `ExecStartPre=/usr/bin/sudo -n .../left4me-overlay mount %i`
so the overlay is established before the main process starts.
- Helper is now idempotent: if merged is already a mount point, exit 0.
Required because Restart=on-failure re-runs ExecStartPre on each
cycle, and the web-app's start_instance also calls the helper, so
both paths would otherwise collide on "already mounted".
- StartLimitBurst=5 + StartLimitIntervalSec=60s caps the restart loop
instead of letting it spin indefinitely on a fundamental failure.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
