use docker configs to replace bind mount configuration files

[jeremyhayes]

When running a swarm service with configuration files, the bind mount expects the file to be available (and identical) on each node, otherwise it can only effectively run from the manager.

• https://docs.docker.com/engine/swarm/configs/
• https://docs.docker.com/compose/compose-file/compose-file-v3/#configs

Impacts:

• grafana
• prometheus
• traefik

[jeremyhayes]

• grafana: ef57166
• prometheus: 5af37aa

[jeremyhayes]

Traefik has a couple challenges:

• the acme.json is a bind-mount, but needs to be writable
• the dynamic routes are in a mounted directory; the single-file volume didn't seem to work