I was able to get it running with the docker compose CA app and minimal changes to the official docker-compose file (docs). I'm running swag in front of the lemmy proxy with no issues with federation. Ibracorp's tutorial can help with the compose plugin

You'll need to make sure the volume locations and ports are appropriate for your unraid install. You'll also have to update your domain in the compose file. I'm running swag so I needed to make a new reverse proxy configuration per the official docs.

My compose file is below:

version: "3.7"

x-logging: &default-logging
  driver: "json-file"
  options:
    max-size: "50m"
    max-file: 4

networks:
  # communication to web and clients
  lemmyexternalproxy:
    name: proxynet
    external: true
  # communication between lemmy services
  lemmyinternal:
    driver: bridge
    internal: true

services:
  proxy:
    image: nginx:1-alpine
    networks:
      - lemmyinternal
      - lemmyexternalproxy
    ports:
      # actual and only port facing any connection from outside
      # Note, change the left number if port 1236 is already in use on your system
      # You could use port 80 if you won't use a reverse proxy
      - "8536:8536"
    volumes:
      #- nginx.conf:/etc/nginx/nginx.conf:ro,Z
      - /mnt/user/appdata/lemmy-nginx/nginx.conf:/etc/nginx/nginx.conf:ro
    restart: always
    depends_on:
      - pictrs
      - lemmy-ui
    logging: *default-logging

  lemmy:
    image: dessalines/lemmy:0.18.0
    #image: dessalines/lemmy:dev
    # use this to build your local lemmy server image for development
    # run docker compose up --build
    # build:
    #  context: ../
    #  dockerfile: docker/Dockerfile
      # args:
      #   RUST_RELEASE_MODE: release
    # this hostname is used in nginx reverse proxy and also for lemmy ui to connect to the backend, do not change
    hostname: lemmy
    networks:
      - lemmyinternal
      - lemmyexternalproxy
    restart: always
    environment:
      - RUST_LOG="warn,lemmy_server=debug,lemmy_api=debug,lemmy_api_common=debug,lemmy_api_crud=debug,lemmy_apub=debug,lemmy_db_schema=debug,lemmy_db_views=debug,lemmy_db_views_actor=debug,lemmy_db_views_moderator=debug,lemmy_routes=debug,lemmy_utils=debug,lemmy_websocket=debug"
      - RUST_BACKTRACE=full
      - LEMMY_CORS_ORIGIN=
    volumes:
      - /mnt/user/appdata/lemmy/lemmy.hjson:/config/config.hjson
    depends_on:
      - postgres
      - pictrs
    logging: *default-logging

  lemmy-ui:
    #image: dessalines/lemmy-ui:latest
    image: dessalines/lemmy-ui:0.18.0
    # use this to build your local lemmy ui image for development
    # run docker compose up --build
    # assuming lemmy-ui is cloned besides lemmy directory
    # build:
    #   context: ../../lemmy-ui
    #   dockerfile: dev.dockerfile
    networks:
      - lemmyinternal
    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_UI_LEMMY_EXTERNAL_HOST=
      - LEMMY_HTTPS=false
      - LEMMY_UI_DEBUG=true
    depends_on:
      - lemmy
    restart: always
    logging: *default-logging
    init: true

  pictrs:
    image: asonix/pictrs:0.4.0-rc.7
    # 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:
      - lemmyinternal
    environment:
      - PICTRS_OPENTELEMETRY_URL=http://otel:4137
      - PICTRS__API_KEY=API_KEY
      - RUST_LOG=debug
      - RUST_BACKTRACE=full
      - PICTRS__MEDIA__VIDEO_CODEC=vp9
      - PICTRS__MEDIA__GIF__MAX_WIDTH=256
      - PICTRS__MEDIA__GIF__MAX_HEIGHT=256
      - PICTRS__MEDIA__GIF__MAX_AREA=65536
      - PICTRS__MEDIA__GIF__MAX_FRAME_COUNT=400
    user: 991:991
    volumes:
      - /mnt/user/appdata/lemmy-pictrs:/mnt
    restart: always
    logging: *default-logging

  postgres:
    image: postgres:15-alpine
    # this needs to match the database host in lemmy.hson
    # Tune your settings via
    # https://pgtune.leopard.in.ua/#/
    # You can use this technique to add them here
    # https://stackoverflow.com/a/30850095/1655478
    hostname: postgres
    command:
      [
        "postgres",
        "-c",
        "session_preload_libraries=auto_explain",
        "-c",
        "auto_explain.log_min_duration=5ms",
        "-c",
        "auto_explain.log_analyze=true",
        "-c",
        "track_activity_query_size=1048576",
      ]
    networks:
      - lemmyinternal
      # adding the external facing network to allow direct db access for devs
      - lemmyexternalproxy
    ports:
      # use a different port so it doesnt conflict with potential postgres db running on the host
      - "5433:5432"
    environment:
      - POSTGRES_USER=
      - POSTGRES_PASSWORD=
      - POSTGRES_DB=lemmy
    volumes:
      - /mnt/user/appdata/lemmy-postgres:/var/lib/postgresql/data
    restart: always
    logging: *default-logging