Google Cloud Source Repositories now GA and free for five users and 50GB storage
cloudplatform.googleblog.com
cloudplatform.googleblog.com
I'm working on an open source[1] PaaS platform which makes integrating managed services a breeze and more accessible on GCP[2].
'are excited to announce that it's leaving beta and is now generally available' - OP
If you need more powerful CI/CD system on gcp, checkout www.datacol.io ( I am the author, so little biased )
E.g., we keep our main private repo at gihub, but when we want to auto-build a Docker image, push to the Google remote. Google's build trigger has been r/o granted access to the repo, clones the code, builds and publishes a private image.