services:
  maindns:
    image: internetsystemsconsortium/bind9:9.18
    container_name: maindns
    command: -u root -g -d 9 -f -c /etc/bind/named.conf
    volumes:
      - maindns_etc_bind:/etc/bind
      - ./maindns_named.conf:/etc/bind/named.conf:ro
      - ./db.example.com:/etc/bind/db.example.com:ro
    tmpfs:
      - /var/cache/bind
      - /var/log
    depends_on:
      - subdns
    networks:
      dnsnet:
        ipv4_address: 172.20.0.10

  subdns:
    image: internetsystemsconsortium/bind9:9.18
    command: -u root -g -d 9 -f -c /etc/bind/named.conf
    container_name: subdns
    volumes:
      - subdns_etc_bind:/etc/bind
      - ./subdns_named.conf:/etc/bind/named.conf:ro
      - ./db.sub.example.com:/etc/bind/db.sub.example.com:ro
    tmpfs:
      - /var/cache/bind
      - /var/log
    networks:
      dnsnet:
        ipv4_address: 172.20.0.20

  client:
    build:
      dockerfile: client_Dockerfile
    container_name: client
    command: sleep infinity
    depends_on:
      - maindns
    dns:
      - 172.20.0.10
    networks:
      dnsnet:
        ipv4_address: 172.20.0.100

networks:
  dnsnet:
    driver: bridge
    ipam:
      config:
        - subnet: 172.20.0.0/24

volumes:
  maindns_etc_bind:
  subdns_etc_bind: