The hardcoded uid:gid in libreportal.backup.files labels was brittle: matched the
default PUID in the compose, but a PUID change (or new image version) would drift
silently and the next restore would chown to a stale owner. Make it impossible to
drift by letting the engine learn the uid at capture time.
backup_files.sh:
- After a successful tar capture, run `stat -c '%u:%g'` inside the container and
write the result to a <host_subdir>.lp-owner sidecar in staging. The sidecar
rides in the snapshot alongside the captured tree.
- Restore reads it back when the descriptor doesn't pin uid:gid; falls back to
0:0 with a clear notice if missing.
- The 5-field form (with explicit uid:gid) is still supported as an override; it
wins and skips the sidecar write entirely.
Update all 4 current labels to the new 3-field form
"<container>:<container_path>:<host_subdir>" (nextcloud, bookstack, gitea,
owncloud). Engine handles both formats during the transition.
Verified with stubs: 3-field capture writes the sidecar with the discovered
33:33; restore reads it back; 5-field override correctly skips the sidecar
write. backup_files.sh parses.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Signed-off-by: librelad <librelad@digitalangels.vip>
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