cloudbuild.yaml: let Google Cloud Build run our CI script

This can be done with

  gcloud builds submit

or by hooking up a CI system.

Change-Id: I07b1967ffd239aab1ed8a7c7993739f3017be490
Reviewed-on: https://team-review.git.corp.google.com/c/golang/discovery/+/718641
CI-Result: Cloud Build <devtools-proctor-result-processor@system.gserviceaccount.com>
Reviewed-by: Julie Qiu <julieqiu@google.com>

cloudbuild.yaml

@@ -0,0 +1,28 @@
+# Copyright 2020 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+steps:
+
+# Run postgres in a docker container to host the test database.
+- name: 'gcr.io/cloud-builders/docker'
+  args: ['run', '--rm', '-d', '--name', 'pg',
+        # All Cloud Build containers are part of the cloudbuild docker
+        # network. This allows the container in the next step to refer
+        # to this container by its name.
+        '--network', 'cloudbuild',
+        # Create the test database with the same collation as prod (which has
+        # the settings LC_COLLATE=C and LC_CTYPE=C).
+        '-e', 'LANG=C',
+        'postgres:11.4']
+
+# Run the all.bash script in CI mode, using the standard golang docker
+# container. That container is built on a standard Debian image, so it
+# has bash and other common binaries in addition to the go toolchain.
+- name: 'golang:1.13'
+  env:
+  - GO111MODULE=on
+  - GOPROXY=https://proxy.golang.org
+  # Refer to the container started in the above step.
+  - GO_DISCOVERY_DATABASE_TEST_HOST=pg
+  args: ['./all.bash', 'ci']