@andreottica@twtxt.net You must set a few configuration options (I do this via environment variables) like so:

services:
  yarn:
    image: prologic/yarnd:dev
    command: yarnd -d /data -s bitcask:///data/yarn.db
    environment:
      - BASE_URL=https://twtxt.net
      - OPEN_PROFILES=true
      - OPEN_REGISTRATIONS=true
      - ADMIN_USER=prologic
      - API_SIGNING_KEY=xxx
      - COOKIE_SECRET=xxx
      - MAGICLINK_SECRET=xxx
    volumes:
      - yarn:/data
...