postgres_host:
    image: postgres:9.6
    ports:
      - "5440:5432"
    environment:
      - POSTGRES_PASSWORD=dev
      - POSTGRES_USER=dev
      - POSTGRES_DB=monolith_db

dev-deployment_postgres_host_1   docker-entrypoint.sh postgres   Up      0.0.0.0:5440->5432/tcp

....
....
NetworkSettings": {
            "Bridge": "",
            "SandboxID": "177d7253627d0e7ce4383e9158eaa72b59b92049c9c7f4f0fe6ee064b27c4bbc",
            "HairpinMode": false,
            "LinkLocalIPv6Address": "",
            "LinkLocalIPv6PrefixLen": 0,
            "Ports": {
                "5432/tcp": [
                    {
                        "HostIp": "0.0.0.0",
                        "HostPort": "5440"
                    }
                ]
            }

$ psql -U dev -h 0.0.0.0 -p 5440 -d monolith_db
psql: server closed the connection unexpectedly
  This probably means the server terminated abnormally
  before or while processing the request.