Add cloudbuild.yaml file (#336)

Author: mkumatag

cloudbuild.yaml

@@ -0,0 +1,18 @@
+# See https://cloud.google.com/cloud-build/docs/build-config
+timeout: 3000s
+options:
+  substitution_option: ALLOW_LOOSE
+steps:
+  - name: 'gcr.io/k8s-testimages/gcb-docker-gcloud:v20210722-085d930'
+    entrypoint: make
+    env:
+      - DOCKER_CLI_EXPERIMENTAL=enabled
+      - TAG=$_GIT_TAG
+      - PULL_BASE_REF=$_PULL_BASE_REF
+    args:
+      - release-staging
+substitutions:
+  # _GIT_TAG will be filled with a git-based tag for the image, of the form vYYYYMMDD-hash, and
+  # can be used as a substitution
+  _GIT_TAG: '12345'
+  _PULL_BASE_REF: 'dev'