An automated rollback tool for Nomulus (#847)

* An automated rollback tool for Nomulus

A tool that directs traffic between deployed versions. It handles the
conversion between Nomulus tags and AppEngine versions, executes schema
compatibility tests, ensures that steps are executed in the correct order,
and updates deployment records appropriately.

release/rollback/gcs_test.py

@@ -0,0 +1,152 @@
+# Copyright 2020 The Nomulus Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Unit tests for gcs."""
+import textwrap
+import unittest
+from unittest import mock
+
+import common
+import gcs
+
+
+def setup_gcs_client(env: str):
+    """Sets up a mocked GcsClient.
+
+    Args:
+        env:  Name of the Nomulus environment.
+
+    Returns:
+        A GcsClient instance and two mocked blobs representing the two schema
+        tag file and version map file on GCS.
+    """
+
+    schema_tag_blob = mock.MagicMock()
+    schema_tag_blob.download_as_text.return_value = 'tag\n'
+    version_map_blob = mock.MagicMock()
+    blobs_by_name = {
+        f'nomulus.{env}.versions': version_map_blob,
+        f'sql.{env}.tag': schema_tag_blob
+    }
+
+    bucket = mock.MagicMock()
+    bucket.get_blob.side_effect = lambda blob_name: blobs_by_name[blob_name]
+    google_client = mock.MagicMock()
+    google_client.get_bucket.return_value = bucket
+    gcs_client = gcs.GcsClient('project', google_client)
+
+    return (gcs_client, schema_tag_blob, version_map_blob)
+
+
+class GcsTestCase(unittest.TestCase):
+    """Unit tests for gcs."""
+    _ENV = 'crash'
+
+    def setUp(self) -> None:
+        self._client, self._schema_tag_blob, self._version_map_blob = \
+            setup_gcs_client(self._ENV)
+        self.addCleanup(mock.patch.stopall)
+
+    def test_get_schema_tag(self):
+        self.assertEqual(self._client.get_schema_tag(self._ENV), 'tag')
+
+    def test_get_versions_by_release(self):
+        self._version_map_blob.download_as_text.return_value = \
+            'nomulus-20200925-RC02,backend,nomulus-backend-v008'
+        self.assertEqual(
+            self._client.get_versions_by_release(self._ENV,
+                                                 'nomulus-20200925-RC02'),
+            frozenset([common.VersionKey('backend', 'nomulus-backend-v008')]))
+
+    def test_get_versions_by_release_not_found(self):
+        self._version_map_blob.download_as_text.return_value = \
+            'nomulus-20200925-RC02,backend,nomulus-backend-v008'
+        self.assertEqual(
+            self._client.get_versions_by_release(self._ENV, 'no-such-tag'),
+            frozenset([]))
+
+    def test_get_versions_by_release_multiple_service(self):
+        self._version_map_blob.download_as_text.return_value = textwrap.dedent(
+            """\
+            nomulus-20200925-RC02,backend,nomulus-backend-v008
+            nomulus-20200925-RC02,default,nomulus-default-v008
+            """)
+        self.assertEqual(
+            self._client.get_versions_by_release(self._ENV,
+                                                 'nomulus-20200925-RC02'),
+            frozenset([
+                common.VersionKey('backend', 'nomulus-backend-v008'),
+                common.VersionKey('default', 'nomulus-default-v008')
+            ]))
+
+    def test_get_versions_by_release_multiple_deployment(self):
+        self._version_map_blob.download_as_text.return_value = textwrap.dedent(
+            """\
+            nomulus-20200925-RC02,backend,nomulus-backend-v008
+            nomulus-20200925-RC02,backend,nomulus-backend-v018
+            """)
+        self.assertEqual(
+            self._client.get_versions_by_release(self._ENV,
+                                                 'nomulus-20200925-RC02'),
+            frozenset([
+                common.VersionKey('backend', 'nomulus-backend-v008'),
+                common.VersionKey('backend', 'nomulus-backend-v018')
+            ]))
+
+    def test_get_releases_by_versions(self):
+        self._version_map_blob.download_as_text.return_value = textwrap.dedent(
+            """\
+            nomulus-20200925-RC02,backend,nomulus-backend-v008
+            nomulus-20200925-RC02,default,nomulus-default-v008
+            """)
+        self.assertEqual(
+            self._client.get_releases_by_versions(
+                self._ENV, {
+                    common.VersionKey('backend', 'nomulus-backend-v008'),
+                    common.VersionKey('default', 'nomulus-default-v008')
+                }), {
+                    common.VersionKey('backend', 'nomulus-backend-v008'):
+                    'nomulus-20200925-RC02',
+                    common.VersionKey('default', 'nomulus-default-v008'):
+                    'nomulus-20200925-RC02',
+                })
+
+    def test_get_recent_deployments(self):
+        file_content = textwrap.dedent("""\
+            nomulus-20200925-RC02,backend,nomulus-backend-v008
+            nomulus-20200925-RC02,default,nomulus-default-v008
+            """)
+        self._version_map_blob.download_as_text.return_value = file_content
+        self.assertEqual(
+            self._client.get_recent_deployments(self._ENV, 2), {
+                common.VersionKey('default', 'nomulus-default-v008'):
+                'nomulus-20200925-RC02',
+                common.VersionKey('backend', 'nomulus-backend-v008'):
+                'nomulus-20200925-RC02'
+            })
+
+    def test_get_recent_deployments_fewer_lines(self):
+        self._version_map_blob.download_as_text.return_value = textwrap.dedent(
+            """\
+            nomulus-20200925-RC02,backend,nomulus-backend-v008
+            nomulus-20200925-RC02,default,nomulus-default-v008
+            """)
+        self.assertEqual(
+            self._client.get_recent_deployments(self._ENV, 1), {
+                common.VersionKey('default', 'nomulus-default-v008'):
+                'nomulus-20200925-RC02'
+            })
+
+
+if __name__ == '__main__':
+    unittest.main()