I’m having the issue that Docker containers don’t get an IPv6 address assigned and therefore are unable to connect to IPv6-only hosts.

I was able to solve this issue for regular Docker containers (started with docker run) by adding a file /etc/docker/daemon.json with this contents:

{
    "ipv6": true,
    "fixed-cidr-v6": "fd00:ffff::/80",
    "ip6tables": true,
    "experimental": true
}

But apparently this isn’t enough for containers that are started by Docker Compose. I found that adding

networks:
  default:
    enable_ipv6: true
    ipam:
      config:
        - subnet: fd00:1:1:1:1::/80

to docker-compose.yml fixes the issue.

Unfortunately this requires me to edit docker-compose.yml for each service I’m running and often those are managed by the vendor through Git, so every time I update the software I have to make sure I keep the modification in docker-compose.yml.

Is there a way to configure Docker so that containers started by Docker Compose get an IPv6 address without modifying docker-compose.yml?