Add google-endpoints to third_party/.

third_party/google-endpoints/google/api/config/service_config.py

+# Copyright 2016 Google Inc. 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.
+
+"""Provides a method for fetching Service Configuration from Google Service
+Management API."""
+
+
+import logging
+import json
+import os
+import urllib3
+
+from apitools.base.py import encoding
+import google.api.gen.servicecontrol_v1_messages as messages
+from oauth2client import client
+from urllib3.contrib import appengine
+
+
+logger = logging.getLogger(__name__)
+
+_GOOGLE_API_SCOPE = "https://www.googleapis.com/auth/cloud-platform"
+
+_SERVICE_MGMT_URL_TEMPLATE = ("https://servicemanagement.googleapis.com"
+                              "/v1/services/{}/configs/{}")
+
+_SERVICE_NAME_ENV_KEY = "ENDPOINTS_SERVICE_NAME"
+_SERVICE_VERSION_ENV_KEY = "ENDPOINTS_SERVICE_VERSION"
+
+
+def fetch_service_config(service_name=None, service_version=None):
+  """Fetches the service config from Google Serivce Management API.
+
+  Args:
+    service_name: the service name. When this argument is unspecified, this
+      method uses the value of the "SERVICE_NAME" environment variable as the
+      service name, and raises ValueError if the environment variable is unset.
+    service_version: the service version. When this argument is unspecified,
+      this method uses the value of the "SERVICE_VERSION" environment variable
+      as the service version, and raises ValueError if the environment variable
+      is unset.
+
+  Returns: the fetched service config JSON object.
+
+  Raises:
+    ValueError: when the service name/version is neither provided as an
+      argument or set as an environment variable; or when the fetched service
+      config fails validation.
+    Exception: when the Google Service Management API returns non-200 response.
+  """
+  if not service_name:
+    service_name = _get_env_var_or_raise(_SERVICE_NAME_ENV_KEY)
+  if not service_version:
+    service_version = _get_env_var_or_raise(_SERVICE_VERSION_ENV_KEY)
+
+  service_mgmt_url = _SERVICE_MGMT_URL_TEMPLATE.format(service_name,
+                                                       service_version)
+
+  access_token = _get_access_token()
+  headers = {"Authorization": "Bearer {}".format(access_token)}
+
+  http_client = _get_http_client()
+  response = http_client.request("GET", service_mgmt_url, headers=headers)
+
+  status_code = response.status
+  if status_code != 200:
+    message_template = "Fetching service config failed (status code {})"
+    _log_and_raise(Exception, message_template.format(status_code))
+
+  logger.debug('obtained service json from the management api:\n%s', response.data)
+  service = encoding.JsonToMessage(messages.Service, response.data)
+  _validate_service_config(service, service_name, service_version)
+  return service
+
+
+def _get_access_token():
+  credentials = client.GoogleCredentials.get_application_default()
+  if credentials.create_scoped_required():
+    credentials = credentials.create_scoped(_GOOGLE_API_SCOPE)
+  return credentials.get_access_token().access_token
+
+
+def _get_http_client():
+  if appengine.is_appengine_sandbox():
+    return appengine.AppEngineManager()
+  else:
+    return urllib3.PoolManager()
+
+
+def _get_env_var_or_raise(env_variable_name):
+  if env_variable_name not in os.environ:
+    message_template = 'The "{}" environment variable is not set'
+    _log_and_raise(ValueError, message_template.format(env_variable_name))
+  return os.environ[env_variable_name]
+
+
+def _validate_service_config(service, expected_service_name,
+                             expected_service_version):
+  service_name = service.name
+  if not service_name:
+    _log_and_raise(ValueError, "No service name in the service config")
+  if service_name != expected_service_name:
+    message_template = "Unexpected service name in service config: {}"
+    _log_and_raise(ValueError, message_template.format(service_name))
+
+  service_version = service.id
+  if not service_version:
+    _log_and_raise(ValueError, "No service version in the service config")
+  if service_version != expected_service_version:
+    message_template = "Unexpected service version in service config: {}"
+    _log_and_raise(ValueError, message_template.format(service_version))
+
+
+def _log_and_raise(exception_class, message):
+  logger.error(message)
+  raise exception_class(message)