BigQuery: user credentials to run a query. (#925)

* BigQuery: user credentials to run a query.

* BigQuery user creds sample: add tests.

Mocks out user credentials using the Application Default Credentials,
but uses the same scopes.

Author: tswast

bigquery/cloud-client/requirements.txt

@@ -1,2 +1,3 @@
 google-cloud-bigquery==0.24.0
+google-auth-oauthlib==0.0.1
 pytz==2017.2

bigquery/cloud-client/user_credentials.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python
+
+# Copyright 2017 Google Inc.
+#
+# 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.
+
+"""Command-line application to run a query using user credentials.
+
+You must supply a client secrets file, which would normally be bundled with
+your application.
+"""
+
+import argparse
+import time
+import uuid
+
+from google.cloud import bigquery
+from google_auth_oauthlib import flow
+
+
+def wait_for_job(job):
+    while True:
+        job.reload()  # Refreshes the state via a GET request.
+        if job.state == 'DONE':
+            if job.error_result:
+                raise RuntimeError(job.errors)
+            return
+        time.sleep(1)
+
+
+def run_query(credentials, project, query):
+    client = bigquery.Client(project=project, credentials=credentials)
+    query_job = client.run_async_query(str(uuid.uuid4()), query)
+    query_job.use_legacy_sql = False
+    query_job.begin()
+
+    wait_for_job(query_job)
+
+    # Drain the query results by requesting a page at a time.
+    query_results = query_job.results()
+    page_token = None
+
+    while True:
+        rows, total_rows, page_token = query_results.fetch_data(
+            max_results=10,
+            page_token=page_token)
+
+        for row in rows:
+            print(row)
+
+        if not page_token:
+            break
+
+
+def authenticate_and_query(project, query, launch_browser=True):
+    appflow = flow.InstalledAppFlow.from_client_secrets_file(
+        'client_secrets.json',
+        scopes=['https://www.googleapis.com/auth/bigquery'])
+
+    if launch_browser:
+        appflow.run_local_server()
+    else:
+        appflow.run_console()
+
+    run_query(appflow.credentials, project, query)
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(
+        description=__doc__,
+        formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument(
+        '--launch-browser',
+        help='Use a local server flow to authenticate. ',
+        action='store_true')
+    parser.add_argument('project', help='Project to use for BigQuery billing.')
+    parser.add_argument('query', help='BigQuery SQL Query.')
+
+    args = parser.parse_args()
+
+    authenticate_and_query(
+        args.project, args.query, launch_browser=args.launch_browser)

bigquery/cloud-client/user_credentials_test.py

@@ -0,0 +1,41 @@
+# Copyright 2017 Google Inc.
+#
+# 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.
+
+import os
+
+import google.auth
+import mock
+import pytest
+
+from user_credentials import authenticate_and_query
+
+
+PROJECT = os.environ['GCLOUD_PROJECT']
+
+
+@pytest.fixture
+def mock_flow():
+    flow_patch = mock.patch(
+        'google_auth_oauthlib.flow.InstalledAppFlow', autospec=True)
+
+    with flow_patch as flow_mock:
+        flow_mock.from_client_secrets_file.return_value = flow_mock
+        flow_mock.credentials = google.auth.default()[0]
+        yield flow_mock
+
+
+def test_auth_query_console(mock_flow, capsys):
+    authenticate_and_query(PROJECT, 'SELECT 1+1;', launch_browser=False)
+    out, _ = capsys.readouterr()
+    assert '2' in out