Deploy SQL schema from Cloud Build (#350)

Defined Docker image for schema deployment.

Included schema deploymer docker in the Cloud Build release process.

Defined Cloud Build config for schema deployment.

TESTED=Used cloud-build-local to test deployment flow
TESTED=Used docker to test schema deployer image in more ways

release/cloudbuild-release.yaml

@@ -98,6 +98,37 @@ steps:
       sed s/'$${_ENV}'/${environment}/g release/cloudbuild-deploy.yaml \
         > release/cloudbuild-deploy-${environment}.yaml
     done
+# Build the schema_deployer image and upload it to GCR.
+- name: 'gcr.io/cloud-builders/docker'
+  entrypoint: /bin/bash
+  args:
+  - -c
+  - |
+    set -e
+    docker build -t gcr.io/${PROJECT_ID}/schema_deployer:${TAG_NAME} .
+    docker tag gcr.io/${PROJECT_ID}/schema_deployer:${TAG_NAME} \
+      gcr.io/${PROJECT_ID}/schema_deployer:latest
+    docker push gcr.io/${PROJECT_ID}/schema_deployer:latest
+    docker push gcr.io/${PROJECT_ID}/schema_deployer:${TAG_NAME}
+  dir: 'release/schema-deployer/'
+# Do text replacement in the schema-deploy config, hardcoding image digests.
+- name: 'gcr.io/cloud-builders/gcloud'
+  entrypoint: /bin/bash
+  args:
+  - -c
+  - |
+    set -e
+    builder_digest=$( \
+      gcloud container images list-tags gcr.io/${PROJECT_ID}/builder \
+      --format='get(digest)' --filter='tags = ${TAG_NAME}')
+    schema_deployer_digest=$( \
+      gcloud container images list-tags gcr.io/${PROJECT_ID}/schema_deployer \
+      --format='get(digest)' --filter='tags = ${TAG_NAME}')
+    sed -i s/builder:latest/builder@$builder_digest/g \
+      release/cloudbuild-schema-deploy.yaml
+    sed -i s/schema_deployer:latest/schema_deployer@$schema_deployer_digest/g \
+      release/cloudbuild-schema-deploy.yaml
+    sed -i s/'$${TAG_NAME}'/${TAG_NAME}/g release/cloudbuild-schema-deploy.yaml
 # Upload the gradle binary to GCS if it does not exist and point URL in gradle wrapper to it.
 - name: 'gcr.io/cloud-builders/gsutil'
   entrypoint: /bin/bash