When both services restart simultaneously (e.g. in all-at-once mode),
Traefik may momentarily truncate or reinitialize acme.json, causing
the certs dumper to read an empty file and panic. By adding
Requires/After on the Traefik service, the certs dumper only starts
after Traefik is fully ready and acme.json is stable.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>