Compose Network Configurations

The top-level networks key lets you specify networks to be created. Here are some of the important docker compose network configurations.

driver

Specify which driver should be used for this network.

The default driver depends on how the Docker Engine you’re using is configured, but in most instances, it will be bridge on a single host and overlay on a Swarm.

The Docker Engine will return an error if the driver is not available.

driver: overlay

driver_opts

Specify a list of options as key-value pairs to pass to the driver for this network. Those options are driver-dependent - consult the driver’s documentation for more information. Optional.

 driver_opts:
    foo: "bar"
    baz: 1

ipam

Specify custom IPAM config. This is an object with several properties, each of which is optional:

• driver: Custom IPAM driver, instead of the default.
• config: A list with zero or more config blocks, each containing any of the following keys:
  • subnet: Subnet in CIDR format that represents a network segment
  • ip_range: Range of IPs from which to allocate container IPs
  • gateway: IPv4 or IPv6 gateway for the master subnet
  • aux_addresses: Auxiliary IPv4 or IPv6 addresses are used by the Network driver, as a mapping from hostname to IP

A full example:

ipam:
  driver: default
  config:
    - subnet: 172.28.0.0/16
      ip_range: 172.28.5.0/24
      gateway: 172.28.5.254
      aux_addresses:
        host1: 172.28.1.5
        host2: 172.28.1.6
        host3: 172.28.1.7

external

If set to true, specifies that this network has been created outside of Compose. docker-compose up will not attempt to create it, and will raise an error if it doesn’t exist.

external cannot be used in conjunction with other network configuration keys (driver, driver_opts, ipam).

In the example below, proxy is the gateway to the outside world. Instead of attempting to create a network called [projectname]_outside, Compose will look for an existing network simply called outside and connect the proxy service’s containers to it.

version: '2'

services:
  proxy:
    build: ./proxy
    networks:
      - outside
      - default
  app:
    build: ./app
    networks:
      - default

networks:
  outside:
    external: true

You can also specify the name of the network separately from the name used to refer to it within the Compose file:

networks:
  outside:
    external:
      name: actual-name-of-network