Bookstack with traefik as reverse proxy

I'm trying to set up Bookstack with traefik as a reverse proxy. traefik is already set up and running fine with Nextcloud and other services.

I'm using the image provide by linuxserver and am modifying the docker-compose file as follows:

version: "2"
services:
  bookstack:
    image: lscr.io/linuxserver/bookstack
    container_name: bookstack
    environment:
      - PUID=1000
      - PGID=1000
      - APP_URL=my-sub.domain.com
      - DB_HOST=bookstack_db
      - DB_USER=dbusernamesetbyme
      - DB_PASS=thedbpasswordichose
      - DB_DATABASE=bookstackapp
    volumes:
      - /path/to/data:/config
    ports:
      - 6875:80
    restart: unless-stopped
    depends_on:
      - bookstack_db
  bookstack_db:
    image: lscr.io/linuxserver/mariadb
    container_name: bookstack_db
    environment:
      - PUID=1000
      - PGID=1000
      - MYSQL_ROOT_PASSWORD=modifiedpassword
      - TZ=Europe/Berlin
      - MYSQL_DATABASE=bookstackapp
      - MYSQL_USER=usernamesetbyme
      - MYSQL_PASSWORD=anotherpassword
    volumes:
      - /path/to/data:/config
    restart: unless-stopped
    labels:
      traefik.enable: "true" 
      traefik.http.routers.bookstack.entrypoints: "http" 
      traefik.http.routers.bookstack.rule: "Host(`my-sub.domain.de`)"
      traefik.http.middlewares.bookstack-https-redirect.redirectscheme.scheme: "https" 
      traefik.http.routers.bookstack.middlewares: "bookstack-https-redirect" 
      traefik.http.routers.bookstack-secure.entrypoints: "https" 
      traefik.http.routers.bookstack-secure.rule: "Host(`my-sub.domain.com`)"
      traefik.http.routers.bookstack-secure.tls: "true" 
      traefik.http.routers.bookstack-secure.tls.certresolver: "http" 
      traefik.http.routers.bookstack-secure.service: "bookstack" 
      traefik.http.services.bookstack.loadbalancer.server.port: "80" 
      traefik.docker.network: "nameofmyproxynetwork" 
   networks:
     - nameofmyproxynetwork

When I call my-sub.domain.com I get a Gateway Timeout. If I leave out the labels and the APP_URL, I can call bookstack via the host-ip and the port e. g. 101.101.101.101:6875 it works just fine.

Any ideas?

Best regards!

So, I've got some external help and got a .yml-file that worked:

version: "3.7"
services:
  bookstack:
    image: linuxserver/bookstack:latest
    container_name: bookstack
    environment:
      - APP_URL=https://my-sub.domain.com
      - TZ=Europe/Berlin
      # - PUID= # = stat ./bookstack/app --format "%u"
      # - PGID= # = stat ./bookstack/app --format "%g"
      - DB_HOST=bookstack_db
      - DB_DATABASE=bookstackdb
      - DB_USERNAME=<dbuser>
      - DB_PASSWORD=<dbpassword>
    volumes:
      - ./bookstack/app:/config
    ports:
      - 6875:80
    restart: unless-stopped
    depends_on:
      - bookstack_db
    labels:
      traefik.enable: "true"
      traefik.docker.network: "proxy"
      traefik.http.routers.bookstack.entrypoints: "http"
      traefik.http.routers.bookstack.rule: "Host(`my-sub.domain.com`)"
      traefik.http.middlewares.bookstack-https-redirect.redirectscheme.scheme: "https"
      traefik.http.routers.bookstack.middlewares: "bookstack-https-redirect"
      traefik.http.routers.bookstack-secure.entrypoints: "https"
      traefik.http.routers.bookstack-secure.rule: "Host(`my-sub.domain.com`)"
      traefik.http.routers.bookstack-secure.tls: "true"
      traefik.http.routers.bookstack-secure.tls.certresolver: "http"
      traefik.http.services.bookstack.loadbalancer.server.port: "80"
    networks:
     - default
     - proxy
  bookstack_db:
    image: lscr.io/linuxserver/mariadb
    container_name: bookstack_db
    environment:
      - TZ=Europe/Berlin
      - MYSQL_ROOT_PASSWORD=<dbrootpassword>
      - MYSQL_DATABASE=bookstackdb
      - MYSQL_USER=<dbuser>
      - MYSQL_PASSWORD=<dbpassword>
    volumes:
      - ./bookstack/db:/var/lib/mysql
    restart: unless-stopped
    networks:
     - default
networks:
  default:
    name: bookstack-default
  proxy:
    external: true

One issue of mine was, that I did not realize, that DB_USERNAME and MYSQL_USER, and DB_PASSWORD and MYSQL_PASSWORD had to contain the same variable.

Furthermore I'm going to provide my traefik.yml, as it shows that I did not use the typical labelnames.

api:
  dashboard: true
entryPoints:
  http:
    address: ":80"
  https:
    address: ":443"
providers:
  docker:
    endpoint: "unix:///var/run/docker.sock"
    exposedByDefault: false
  file:
    filename: "./dynamic_conf.yml"
certificatesResolvers:
  http:
    acme:
      email: username@domain.com
      storage: acme.json
      httpChallenge:
        entryPoint: http

Hope that helps somebody else!