Hi all! This is my first real post on the fediverse, coming to you live from my own Lemmy instance, which took me way too long to set up. Turns out, the provided docker-compose.yml file provided by the official Lemmy documentation does not allow outbound access to the internet, which prevents users from seeing other instances on yours. For SEO’s sake, I was receiving the following error message: error trying to connect: dns error: failed to lookup address information: Try again

Anywho, I updated the docker-compose.yml file to put all containers on one network, and allow that network outbound access while restricting inbound access to only ports 80 and 443, which worked a treat.

version: "3.3"

networks:
  lemmy:
    internal: false

services:
  proxy:
    image: nginx:1-alpine
    networks:
      - lemmy
    ports:
      # only ports facing any connection from outside
      - 80:80
      - 443:443
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf:ro
      # setup your certbot and letsencrypt config 
      - ./certbot:/var/www/certbot
      - ./letsencrypt:/etc/letsencrypt/live
    restart: always
    depends_on:
      - pictrs
      - lemmy-ui

  lemmy:
    image: dessalines/lemmy:0.17.4
    hostname: lemmy
    networks:
      - lemmy
    restart: always
    environment:
      - RUST_LOG="warn,lemmy_server=info,lemmy_api=info,lemmy_api_common=info,lemmy_api_crud=info,lemmy_apub=info,lemmy_db_schema=info,lemmy_db_views=info,lemmy_db_views_actor=info,lemmy_db_views_moderator=info,lemmy_routes=info,lemmy_utils=info,lemmy_websocket=info"
    volumes:
      - ./lemmy.hjson:/config/config.hjson
    depends_on:
      - postgres
      - pictrs

  lemmy-ui:
    image: dessalines/lemmy-ui:0.17.4
    networks:
      - lemmy
    environment:
      # this needs to match the hostname defined in the lemmy service
      - LEMMY_UI_LEMMY_INTERNAL_HOST=lemmy:8536
      # set the outside hostname here
      - LEMMY_UI_LEMMY_EXTERNAL_HOST=localhost:1236
      - LEMMY_HTTPS=true
    depends_on:
      - lemmy
    restart: always

  pictrs:
    image: asonix/pictrs:0.3.1
    # this needs to match the pictrs url in lemmy.hjson
    hostname: pictrs
    # we can set options to pictrs like this, here we set max. image size and forced format for conversion
    # entrypoint: /sbin/tini -- /usr/local/bin/pict-rs -p /mnt -m 4 --image-format webp
    networks:
      - lemmy
    environment:
      - PICTRS__API_KEY=API_KEY
    user: 991:991
    volumes:
      - ./volumes/pictrs:/mnt
    restart: always

  postgres:
    image: postgres:15-alpine
    # this needs to match the database host in lemmy.hson
    hostname: postgres
    networks:
      - lemmy
    environment:
      - POSTGRES_USER=lemmy
      - POSTGRES_PASSWORD=password
      - POSTGRES_DB=lemmy
    volumes:
      - ./volumes/postgres:/var/lib/postgresql/data
    restart: always