Experience on migrating from VM CI runners to kubernetes hosted CI runners

Hello,

I plan to migrate 6 runners VM to kubernetes hosted runners.

I would like to make the migration as smooth as possible and not having to edit .gitlab-ci.yaml for every single projects.

From the first tests I have done, there are two problems which require to edit the gitlab-ci configuration file.

Adding following variable to make docker reachable

variables: 
  DOCKER_HOST: tcp://localhost:2375

Default build_dir which is /builds on the VMs but / with the kubernetes executor, it mess up artifacts path.

Do you have any experience on migrating to kubernetes execution with a large amount of projects ?