PRD 0018 chunk 3's atomicity fix used write-temp-then-rename to
update bind-mounted config files. POSIX rename atomically swaps
the inode at the host path — but Docker single-file bind mounts
on Linux pin the source inode at mount time, so post-rename the
container's mount points at the now-orphaned old inode and never
sees the new content. The egress sidecar's SIGHUP-driven reload
re-reads the same stale file → "egress route updates aren't
updatable via the supervisor anymore".
Switch egress_apply + pipelock_apply to write in place (same
inode, truncated + rewritten). Lose file-level POSIX atomicity,
but:
- egress: SIGHUP fires only AFTER the write returns; the
addon's `load_routes` raises `ValueError` on a partial read
and keeps the previous in-memory routes, so the in-process
race window (already narrow) is non-disruptive.
- pipelock: applies via `docker restart` rather than SIGHUP;
restart serializes after the host write completes, so the
container reads the fully-written file on next boot.
macOS Docker Desktop's file-sharing layer (virtiofs / osxfs)
silently re-resolves the path on rename, which is why this bug
didn't surface in dev tests on macOS. Linux native Docker is
the strict reading; the fix works on both.
didericis
3c2585cb98