Add proxy config option to google backup driver

Enable users to specify a proxy URL for connecting the cinder
backup service to GCS.

DocImpact: New config option for google backup driver.
Change-Id: I46d2b5d202644269ed44abded3fab8dcc230e3da
Closes-Bug: #1592730
Co-Authored-By: Ollie Leahy <oliver.leahy@hp.com>

cinder/backup/drivers/google.py

@@ -91,6 +91,10 @@ gcsbackup_service_opts = [
                      'progress notifications to Ceilometer when backing '
                      'up the volume to the GCS backend storage. The '
                      'default value is True to enable the timer.'),
+    cfg.URIOpt('backup_gcs_proxy_url',
+               help='URL for http proxy access.',
+               secret=True),
+
 ]
 
 CONF = cfg.CONF
@@ -134,14 +138,21 @@ class GoogleBackupDriver(chunkeddriver.ChunkedBackupDriver):
         self.bucket_location = CONF.backup_gcs_bucket_location
         self.storage_class = CONF.backup_gcs_storage_class
         self.num_retries = CONF.backup_gcs_num_retries
-        http_user_agent = http.set_user_agent(httplib2.Http(),
-                                              CONF.backup_gcs_user_agent)
+        http_user_agent = http.set_user_agent(
+            httplib2.Http(proxy_info=self.get_gcs_proxy_info()),
+            CONF.backup_gcs_user_agent)
         self.conn = discovery.build('storage',
                                     'v1',
                                     http=http_user_agent,
                                     credentials=credentials)
         self.resumable = self.writer_chunk_size != -1
 
+    def get_gcs_proxy_info(self):
+        if CONF.backup_gcs_proxy_url:
+            return httplib2.proxy_info_from_url(CONF.backup_gcs_proxy_url)
+        else:
+            return httplib2.proxy_info_from_environment()
+
     def check_gcs_options(self):
         required_options = ('backup_gcs_bucket', 'backup_gcs_credential_file',
                             'backup_gcs_project_id')

cinder/tests/unit/backup/drivers/test_backup_google.py

@@ -204,6 +204,20 @@ class GoogleBackupDriverTestCase(test.TestCase):
         service.backup(backup, self.volume_file)
         self.assertEqual('gcscinderbucket', backup.container)
 
+    @gcs_client
+    @mock.patch('httplib2.proxy_info_from_url')
+    def test_backup_proxy_configured(self, mock_proxy_info):
+        google_dr.CONF.set_override("backup_gcs_proxy_url",
+                                    "http://myproxy.example.com")
+        google_dr.GoogleBackupDriver(self.ctxt)
+        mock_proxy_info.assert_called_with("http://myproxy.example.com")
+
+    @gcs_client
+    @mock.patch('httplib2.proxy_info_from_environment')
+    def test_backup_proxy_environment(self, mock_proxy_env):
+        google_dr.GoogleBackupDriver(self.ctxt)
+        mock_proxy_env.assert_called_once_with()
+
     @gcs_client
     @mock.patch('cinder.backup.drivers.google.GoogleBackupDriver.'
                 '_send_progress_end')