How to fix Caddy container generating docker volume with autosave.json

My docker-compose-based Caddy setup re-created the container and hence created a new docker volume with only the autosave.json whenever it was restarted. Since it was auto-restarted once a minute, this led do over 70000 volumes piling up in /var/lib/docker/volumes.

The Caddy log shows that Caddy is creating /config/caddy/autosave.json:

mycaddy_1 | {"level":"info","ts":1637877640.7375677,"msg":"autosaved config (load with --resume flag)","file":"/config/caddy/autosave.json"}

I fixed this by mapping /config/caddy to a local directory:

- ./caddy_data:/config/caddy/

Complete docker-compose.yml example:

services:
  mycaddy:
    image: 'caddy:2.4.6-alpine'
    volumes:
      - ./caddy_data:/config/caddy/
      - ./static:/usr/share/caddy
      - ./Caddyfile:/etc/caddy/Caddyfile
    ports:
      - 19815:80