example docker-compose.yml for kong, postgres and konga

docker-compose.yml

version: "3"

networks:
 kong-net:
  driver: bridge

services:

  #######################################
  # Postgres: The database used by Kong
  #######################################
  kong-database:
    image: postgres:9.6
    restart: always
    networks:
      - kong-net
    environment:
      POSTGRES_USER: kong
      POSTGRES_DB: kong
    ports:
      - "5432:5432"
    healthcheck:
      test: ["CMD", "pg_isready", "-U", "kong"]
      interval: 5s
      timeout: 5s
      retries: 5

  #######################################
  # Kong database migration
  #######################################
  kong-migration:
    image: kong:latest
    command: "kong migrations bootstrap"
    networks:
      - kong-net
    restart: on-failure
    environment:
      KONG_PG_HOST: kong-database
    links:
      - kong-database
    depends_on:
      - kong-database

  #######################################
  # Kong: The API Gateway
  #######################################
  kong:
    image: kong:latest
    restart: always
    networks:
      - kong-net
    environment:
      KONG_PG_HOST: kong-database
      KONG_PROXY_LISTEN: 0.0.0.0:8000
      KONG_PROXY_LISTEN_SSL: 0.0.0.0:8443
      KONG_ADMIN_LISTEN: 0.0.0.0:8001
    depends_on:
      - kong-migration
      - kong-database
    healthcheck:
      test: ["CMD", "curl", "-f", "http://kong:8001"]
      interval: 5s
      timeout: 2s
      retries: 15
    ports:
      - "8001:8001"
      - "8000:8000"

  #######################################
  # Konga database prepare
  #######################################
  konga-prepare:
    image: pantsel/konga:next
    command: "-c prepare -a postgres -u postgresql://kong@kong-database:5432/konga_db"
    networks:
      - kong-net
    restart: on-failure
    links:
      - kong-database
    depends_on:
      - kong-database

  #######################################
  # Konga: Kong GUI
  #######################################
  konga:
    image: pantsel/konga:next
    restart: always
    networks:
        - kong-net
    environment:
      DB_ADAPTER: postgres
      DB_HOST: kong-database
      DB_USER: kong
      TOKEN_SECRET: km1GUr4RkcQD7DewhJPNXrCuZwcKmqjb
      DB_DATABASE: konga_db
      NODE_ENV: production
    depends_on:
      - kong-database
    ports:
      - "1337:1337"

Because postgres always require DB_PASSWORD

To get konga-prepare to work, I had to include the db password in the connection string in the format username:password -
command: "-c prepare -a postgres -u postgresql://kong:kong@kong-database:5432/konga_db"