Build an IPv6 Network with Docker Compose

#docker #linux

✍️ In a previous post, I explained how to enable IPv6 for docker and build a network using the command-line
💪 Here I detail how to do the same with docker compose.
👉 Firstly, I build the network via the command-line then docker compose to attach a container to this network.
🔥 Then, I build the network and container service, all in docker compose.
💻 This demo was uses Ubuntu 21.04 server.

Install docker compose

The docker compose installation notes are here. They worked for me without issue.

sudo curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose

Example 1: Use an existing network with docker compose

Manually create a network using the command-line. This is a user-defined bridge network. See my previous post for details about this type of network.
```
docker network create --ipv6 \
--subnet="2001:db8:1::/64" \
--gateway="2001:db8:1::1" \
mynetv6-1
```

Create a docker-compose.yaml file that utilises the existing mynetv6-1 network.

version: "3.9"
services:
alp1:
image: alpine:latest
command: ping6 -c 4 2001:db8:1::1
networks:
  - mynetv6-1
networks:
mynetv6-1:
external: true

Notes

This file uses version 3.9.
A service alp1 is created that uses the alpine:latest image. This will ping the network gateway to demonstrate successful network & container build.
There is a networks subcommand under services to assign the service to the mynetv6-1 network.
The dedicated networks section references the existing mynetv6-1, and indicates that this network is already live with the external:true attribute. Without this, docker compose will attempt to create a new network for the alp1 service.

Verify

joe@ub5:~/docker-test$ docker-compose up
Creating docker-test_alp1_1 ... done
Attaching to docker-test_alp1_1
alp1_1  | PING 2001:db8:1::1 (2001:db8:1::1): 56 data bytes
alp1_1  | 64 bytes from 2001:db8:1::1: seq=0 ttl=64 time=0.087 ms
alp1_1  | 64 bytes from 2001:db8:1::1: seq=1 ttl=64 time=0.141 ms
alp1_1  | 64 bytes from 2001:db8:1::1: seq=2 ttl=64 time=0.051 ms
alp1_1  | 64 bytes from 2001:db8:1::1: seq=3 ttl=64 time=0.140 ms
alp1_1  |
alp1_1  | --- 2001:db8:1::1 ping statistics ---
alp1_1  | 4 packets transmitted, 4 packets received, 0% packet loss
alp1_1  | round-trip min/avg/max = 0.051/0.104/0.141 ms
docker-test_alp1_1 exited with code 0

Example 2: Build a network and service with docker compose

This example simply requires a docker-compose.yml file.

version: "2.4"
services:
  alp2:
    image: alpine:latest
    command: ping6 -c 4 2001:db8:a::1
    networks:
      - net2
networks:
  net2:
    name: net2
    enable_ipv6: true
    ipam:
      config:
        - subnet: 2001:db8:a::/64
          gateway: 2001:db8:a::1

Notes

Note the version number, enable_ipv6 is not supported in version 3.
This creates a service, with the latest alpine image, attached to the net2 network, and pings the gateway.
The dedicated network section creates net2, enables IPv6, and addresses the subnet and gateway.

Verify

joe@ub5:~/docker-test$ docker-compose up --remove-orphans
Creating network "net2" with the default driver
Recreating docker-test_alp2_1 ... done
Attaching to docker-test_alp2_1
alp2_1  | PING 2001:db8:a::1 (2001:db8:a::1): 56 data bytes
alp2_1  | 64 bytes from 2001:db8:a::1: seq=0 ttl=64 time=2054.280 ms
alp2_1  | 64 bytes from 2001:db8:a::1: seq=1 ttl=64 time=1053.982 ms
alp2_1  | 64 bytes from 2001:db8:a::1: seq=2 ttl=64 time=53.688 ms
alp2_1  | 64 bytes from 2001:db8:a::1: seq=3 ttl=64 time=0.052 ms
alp2_1  |
alp2_1  | --- 2001:db8:a::1 ping statistics ---
alp2_1  | 4 packets transmitted, 4 packets received, 0% packet loss
alp2_1  | round-trip min/avg/max = 0.052/790.500/2054.280 ms
docker-test_alp2_1 exited with code 0