Update standard cloudsql sample to use env vars, cloudsql v2 (GoogleCloudPlatform#556)

Author: Jon Wayne Parrott

appengine/standard/cloudsql/README.md

@@ -8,6 +8,4 @@ Refer to the [App Engine Samples README](../README.md) for information on how to
 
 1. You will need to create a [Cloud SQL instance](https://cloud.google.com/sql/docs/create-instance).
 
-2. Edit the `CLOUDSQL_INSTANCE` and `CLOUDSQL_PROJECT` values in `main.py`.
-
-3. To run locally, you will need to be running a local instance of MySQL. You may need to update the connection code in `main.py` with the appropriate local username and password.
+2. Edit the update the `env_variables` section in `app.yaml` with your Cloud SQL configuration.

appengine/standard/cloudsql/app.yaml

@@ -9,3 +9,10 @@ handlers:
 libraries:
 - name: MySQLdb
   version: "latest"
+
+# [START env_variables]
+env_variables:
+    CLOUDSQL_CONNECTION_NAME: your-connection-name
+    CLOUDSQL_USER: root
+    CLOUDSQL_PASSWORD: your-cloudsql-user-password
+# [END env_variables]

appengine/standard/cloudsql/main.py

@@ -14,40 +14,57 @@
 
 """
 Sample App Engine application demonstrating how to connect to Google Cloud SQL
-using App Engine's native unix socket.
+using App Engine's native unix socket or using TCP when running locally.
 
 For more information, see the README.md.
 """
 
 # [START all]
-
 import os
 
 import MySQLdb
 import webapp2
 
 
-CLOUDSQL_PROJECT = ''
-CLOUDSQL_INSTANCE = ''
+# These environment variables are configured in app.yaml.
+CLOUDSQL_CONNECTION_NAME = os.environ.get('CLOUDSQL_CONNECTION_NAME')
+CLOUDSQL_USER = os.environ.get('CLOUDSQL_USER')
+CLOUDSQL_PASSWORD = os.environ.get('CLOUDSQL_PASSWORD')
+
+
+def connect_to_cloudsql():
+    # When deployed to App Engine, the `SERVER_SOFTWARE` environment variable
+    # will be set to 'Google App Engine/version'.
+    if os.getenv('SERVER_SOFTWARE', '').startswith('Google App Engine/'):
+        # Connect using the unix socket located at
+        # /cloudsql/cloudsql-connection-name.
+        cloudsql_unix_socket = os.path.join(
+            '/cloudsql', CLOUDSQL_CONNECTION_NAME)
+
+        db = MySQLdb.connect(
+            unix_socket=cloudsql_unix_socket,
+            user=CLOUDSQL_USER,
+            passwd=CLOUDSQL_PASSWORD)
+
+    # If the unix socket is unavailable, then try to connect using TCP. This
+    # will work if you're running a local MySQL server or using the Cloud SQL
+    # proxy, for example:
+    #
+    #   $ cloud_sql_proxy -instances=your-connection-name=tcp:3306
+    #
+    else:
+        db = MySQLdb.connect(
+            host='127.0.0.1', user=CLOUDSQL_USER, passwd=CLOUDSQL_PASSWORD)
+
+    return db
 
 
 class MainPage(webapp2.RequestHandler):
     def get(self):
+        """Simple request handler that shows all of the MySQL variables."""
         self.response.headers['Content-Type'] = 'text/plain'
 
-        # When running on Google App Engine, use the special unix socket
-        # to connect to Cloud SQL.
-        if os.getenv('SERVER_SOFTWARE', '').startswith('Google App Engine/'):
-            db = MySQLdb.connect(
-                unix_socket='/cloudsql/{}:{}'.format(
-                    CLOUDSQL_PROJECT,
-                    CLOUDSQL_INSTANCE),
-                user='root')
-        # When running locally, you can either connect to a local running
-        # MySQL instance, or connect to your Cloud SQL instance over TCP.
-        else:
-            db = MySQLdb.connect(host='localhost', user='root')
-
+        db = connect_to_cloudsql()
         cursor = db.cursor()
         cursor.execute('SHOW VARIABLES')
 

appengine/standard/cloudsql/main_test.py

@@ -18,13 +18,19 @@
 import pytest
 import webtest
 
-import main
+
+@pytest.fixture
+def main(monkeypatch):
+    monkeypatch.setenv('CLOUDSQL_USER', 'root')
+    monkeypatch.setenv('CLOUDSQL_PASSWORD', '')
+    import main
+    return main
 
 
 @pytest.mark.skipif(
     not os.path.exists('/var/run/mysqld/mysqld.sock'),
-    reason='MySQL server not available.')
-def test_app():
+    reason='Local MySQL server not available.')
+def test_app(main):
     app = webtest.TestApp(main.app)
     response = app.get('/')