docker-compose networking

default network

docker compose creates a bridge network by default.

services:
  web:
    image: nginx
  db:
    image: postgres

services can communicate using service names as hostnames.

custom bridge network

create a custom bridge network with specific configurations:

networks:
  custom_net:
    driver: bridge
    driver_opts:
      com.docker.network.bridge.name: my-bridge0
    ipam:
      driver: default
      config:
        - subnet: 172.28.0.0/16
          ip_range: 172.28.5.0/24
          gateway: 172.28.5.254

services:
  web:
    image: nginx
    networks:
      - custom_net

key properties:

driver: network driver (bridge, overlay, host, macvlan)
driver_opts: driver-specific options
ipam: ip address management settings

host network

use the host’s network stack:

services:
  web:
    image: nginx
    network_mode: host

port exposure

expose ports to the host:

services:
  web:
    image: nginx
    ports:
      - "8080:80"
    expose:
      - "8000"

ports: publish container ports to host
expose: expose ports without publishing to host

external networks

join an existing network:

networks:
  existing_net:
    external: true
    name: actual_network_name

services:
  web:
    image: nginx
    networks:
      - existing_net

network aliases

create service aliases:

services:
  db:
    image: postgres
    networks:
      backend:
        aliases:
          - database

networks:
  backend:
    driver: bridge

default network configuration

configure the default network:

networks:
  default:
    driver: bridge
    driver_opts:
      com.docker.network.driver.mtu: 1400
    ipam:
      driver: default
      config:
        - subnet: 172.28.0.0/16

disable networking

isolate a service:

services:
  isolated:
    image: alpine
    network_mode: none

custom dns

specify custom dns servers:

networks:
  custom_dns:
    driver: bridge
    dns:
      - 8.8.8.8
      - 8.8.4.4