Answer by Anas El Barkani for How make openvpn work with docker

You can also get docker-compose working if you define the subnet CIDR in your docker compose file:

networks:
  your-network:
   ipam:
      config:
      - subnet: 172.16.238.0/24
        gateway: 172.16.238.1

Another option: create first the network with the subnet CIDR and then specify in the docker compose file that you want to use this network:

docker network create your-network --subnet 172.24.24.0/24

In your docker compose file:

networks:
  your-network:
    external: true