docker+machine executor: IPv6 support
Description
gitlab-runner doesn't allow to enable IPv6 support in the docker runners following suggestions of the docker documentation (link).
Proposal
Add in [[runners.docker]]
options corresponding to the Docker documentation:
ipv6= true
fixed-cidr-v6= "2001:db8:1::/64"
experimental= true
ip6tables = true
which would be propagated to the Docker daemon's configuration on the provisioned machines.
The container running on such Docker daemon would have the IPv6 addresses assigned, be part of the dedicated IPv6 isolated subnet (specified by 'fixed-cidr-v6') and have routing to the Internet.