Bringing local client.py closer to upstream.

This is so that a simple diff is possible.

gcloud_bigtable/_non_upstream_helpers.py

@@ -0,0 +1,215 @@
+# Copyright 2015 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.
+
+"""Helpers needed that are already present in gcloud-python.
+
+They are only needed here, but not needed for merging this upstream.
+"""
+
+
+import os
+import socket
+
+import six
+
+from oauth2client.client import GoogleCredentials
+from oauth2client.client import SignedJwtAssertionCredentials
+from oauth2client.client import _get_application_default_credential_from_file
+
+try:
+    from google.appengine.api import app_identity
+except ImportError:
+    app_identity = None
+
+
+PROJECT_ENV_VAR = 'GCLOUD_PROJECT'
+"""Environment variable used to provide an implicit project ID."""
+
+
+def _project_from_environment():
+    """Attempts to get the project ID from an environment variable.
+
+    :rtype: :class:`str` or :data:`NoneType <types.NoneType>`
+    :returns: The project ID provided or :data:`None`
+    """
+    return os.getenv(PROJECT_ENV_VAR)
+
+
+def _project_from_app_engine():
+    """Gets the App Engine application ID if it can be inferred.
+
+    :rtype: :class:`str` or :data:`NoneType <types.NoneType>`
+    :returns: App Engine application ID if running in App Engine,
+              else :data:`None`.
+    """
+    if app_identity is None:
+        return None
+
+    return app_identity.get_application_id()
+
+
+def _project_from_compute_engine():
+    """Gets the Compute Engine project ID if it can be inferred.
+
+    Uses 169.254.169.254 for the metadata server to avoid request
+    latency from DNS lookup.
+
+    See https://cloud.google.com/compute/docs/metadata#metadataserver
+    for information about this IP address. (This IP is also used for
+    Amazon EC2 instances, so the metadata flavor is crucial.)
+
+    See https://github.com/google/oauth2client/issues/93 for context about
+    DNS latency.
+
+    :rtype: :class:`str` or :data:`NoneType <types.NoneType>`
+    :returns: Compute Engine project ID if the metadata service is available,
+              else :data:`None`.
+    """
+    host = '169.254.169.254'
+    uri_path = '/computeMetadata/v1/project/project-id'
+    headers = {'Metadata-Flavor': 'Google'}
+    connection = six.moves.http_client.HTTPConnection(host, timeout=0.1)
+
+    try:
+        connection.request('GET', uri_path, headers=headers)
+        response = connection.getresponse()
+        if response.status == 200:
+            return response.read()
+    except socket.error:  # socket.timeout or socket.error(64, 'Host is down')
+        pass
+    finally:
+        connection.close()
+
+
+def _determine_project(project=None):
+    """Determine the project ID from the input or environment.
+
+    When checking the environment, the following precedence is observed:
+
+    * GCLOUD_PROJECT environment variable
+    * Google App Engine application ID
+    * Google Compute Engine project ID (from metadata server)
+
+    :type project: str
+    :param project: (Optional) The ID of the project which owns the
+                    clusters, tables and data. If not provided, will attempt
+                    to determine from the environment.
+
+    :rtype: str
+    :returns: The project ID provided or inferred from the environment.
+    :raises: :class:`EnvironmentError` if the project ID was not
+             passed in and can't be inferred from the environment.
+    """
+    if project is None:
+        project = _project_from_environment()
+
+    if project is None:
+        project = _project_from_app_engine()
+
+    if project is None:
+        project = _project_from_compute_engine()
+
+    if project is None:
+        raise EnvironmentError('Project ID was not provided and could not '
+                               'be determined from environment.')
+
+    return project
+
+
+def _get_contents(filename):
+    """Get the contents of a file.
+
+    This is just implemented so we can stub out while testing.
+
+    :type filename: :class:`str` or :func:`unicode <unicode>`
+    :param filename: The name of a file to open.
+
+    :rtype: bytes
+    :returns: The bytes loaded from the file.
+    """
+    with open(filename, 'rb') as file_obj:
+        return file_obj.read()
+
+
+def get_credentials():
+    """Get default credentials."""
+    return GoogleCredentials.get_application_default()
+
+
+class _FactoryMixin(object):
+    """Mixin for factories to get credentials."""
+
+    def __init__(self, project=None, credentials=None):
+        self.project = _determine_project(project)
+        self._credentials = credentials
+
+    @classmethod
+    def from_service_account_json(cls, json_credentials_path, *args, **kwargs):
+        """Factory to retrieve JSON credentials while creating client object.
+
+        :type json_credentials_path: str
+        :param json_credentials_path: The path to a private key file (this file
+                                      was given to you when you created the
+                                      service account). This file must contain
+                                      a JSON object with a private key and
+                                      other credentials information (downloaded
+                                      from the Google APIs console).
+
+        :type args: tuple
+        :param args: Positional arguments.
+
+        :type kwargs: dict
+        :param kwargs: Keyword arguments.
+
+        :rtype: :class:`_FactoryMixin`
+        :returns: The client created with the retrieved JSON credentials.
+        """
+        credentials = _get_application_default_credential_from_file(
+            json_credentials_path)
+        kwargs['credentials'] = credentials
+        return cls(*args, **kwargs)
+
+    @classmethod
+    def from_service_account_p12(cls, client_email, private_key_path,
+                                 *args, **kwargs):
+        """Factory to retrieve P12 credentials while creating client object.
+
+        .. note::
+
+            Unless you have an explicit reason to use a PKCS12 key for your
+            service account, we recommend using a JSON key.
+
+        :type client_email: str
+        :param client_email: The e-mail attached to the service account.
+
+        :type private_key_path: str
+        :param private_key_path: The path to a private key file (this file was
+                                 given to you when you created the service
+                                 account). This file must be in P12 format.
+
+        :type args: tuple
+        :param args: Positional arguments.
+
+        :type kwargs: dict
+        :param kwargs: Keyword arguments.
+
+        :rtype: :class:`_FactoryMixin`
+        :returns: The client created with the retrieved P12 credentials.
+        """
+        credentials = SignedJwtAssertionCredentials(
+            service_account_name=client_email,
+            private_key=_get_contents(private_key_path),
+            scope=None)
+        kwargs['credentials'] = credentials
+        return cls(*args, **kwargs)