Continuous Integration via Cloud Build

Cloud Build is configured to trigger on /gcbrun comment from maintainer in PR to the master branch.

Cloud Build triggers a set of build steps, configured in a cloudbuild.yaml config file. These steps are:

Create a presubmit Docker container with initialization actions code and necessary dependencies installed; this includes git, gcloud, fastunit and parametrized.
Push the presubmit Docker container to Container Registry
Run the presubmit Docker container on Kubernetes Engine cluster. It will execute presubmit.sh script that configures test environment, determines which tests that need to be run and runs them concurrently.
Delete the presubmit Docker container from Container Registry.

Main responsibilities of presubmit.sh script:

Configure gcloud to use encrypted SSH key (ssh-key.enc and ssh-key.pub.enc files) to SSH into Dataproc cluster VMs during tests execution. This prevents new SSH key generation for each test run.
Only run tests if their corresponding initialization action was modified.