Current lemmy.hjson configuration file (with or without the closing bracket…both do not work):

{
  # the domain name of your instance (eg "lemmy.ml")
  hostname: "beehaw.org"
  # Settings related to activitypub federation
  federation: {
    # Whether to enable activitypub federation.
    enabled: true
    # Allows and blocks are described here:
    # https://join-lemmy.org/docs/en/federation/administration.html///instance-allowlist-and-blocklist
    #
    # list of instances with which federation is allowed
    allowed_instances: [
      lemmy.ca
      midwest.social
      /* ... */
    ]
    # Instances which we never federate anything with (but previously federated objects are unaffected)
    blocked_instances: [
      string
      /* ... */
    ]
    # If true, only federate with instances on the allowlist and block everything else. If false
    # use allowlist only for remote communities, and posts/comments in local communities
    # (meaning remote communities will show content from arbitrary instances).
    strict_allowlist: true
    }
}

Docker logs:

lemmy_1     | thread 'main' panicked at 'Error connecting to postgres://lemmy:password@localhost:5432/lemmy', src/main.rs:65:25
lemmy_1     | note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
lemmy_lemmy_1 exited with code 101
lemmy_1     | 2022-01-23T12:53:58.959887Z ERROR r2d2: could not connect to server: Connection refused
lemmy_1     | 	Is the server running on host "localhost" (127.0.0.1) and accepting
lemmy_1     | 	TCP/IP connections on port 5432?
lemmy_1     | could not connect to server: Address not available
lemmy_1     | 	Is the server running on host "localhost" (::1) and accepting
lemmy_1     | 	TCP/IP connections on port 5432?

Safari browser throws this error when attempting to reach https://beehaw.org

https://beehaw.org/404?err=FetchError:%20request%20to%20http://lemmy:8536/api/v3/site?%20failed,%20reason:%20connect%20ECONNREFUSED%20172.23.0.4:8536

So, my instance is connecting from a secured HTTPS and the lemmy connection is attempting to connect to an unsecured HTTP.

docker-compose.yml:

version: '2.2'

services:
  postgres:
    image: postgres:12-alpine
    environment:
      - POSTGRES_USER=lemmy
      - POSTGRES_PASSWORD=thr33n1n3
      - POSTGRES_DB=lemmy
    volumes:
      - ./volumes/postgres:/var/lib/postgresql/data
    restart: always

  lemmy:
    image: dessalines/lemmy:0.15.1
    ports:
      - "127.0.0.1:8536:8536"
    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_ac>
    volumes:
      - ./lemmy.hjson:/config/config.hjson
    depends_on:
      - postgres
      - pictrs

  lemmy-ui:
    image: beehaw/frontend-ui:latest
    ports:
      - "127.0.0.1:1235:1234"
    restart: always
    environment:
      - LEMMY_INTERNAL_HOST=lemmy:8536
      - LEMMY_EXTERNAL_HOST=beehaw.org
      - LEMMY_HTTPS=false
    depends_on:
      - lemmy

  pictrs:
    image: asonix/pictrs:v0.2.6-r2
    ports:
      - "127.0.0.1:8537:8080"
    user: 991:991
    volumes:
      - ./volumes/pictrs:/mnt
    restart: always