Awesome, if you're using Google Cloud you'll be happy to hear that we just merged Kubernetes support for Runner creation https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/merge_r... Giving you the option to use Google Container engine to spin up new Runners.
This is fantastic. Right now I use GCE autoscaling groups to spin up runners while I've got several kubernetes clusters running 24/7. It'll be nice to utilize those for builds (especially with how fast the scheduler is) going forward. Saves money, as well.