fix: lazy init db connection for Cloud Function (GoogleCloudPlatform#10576)

jackwotherspoon · web-flow · commit ef240c52c462 · 2023-08-31T09:15:24.000-04:00
diff --git a/cloud-sql/mysql/sqlalchemy/main.py b/cloud-sql/mysql/sqlalchemy/main.py
@@ -20,10 +20,9 @@
 
 ############ TABS vs. SPACES App for Cloud Functions ############
 
-# initiate a connection pool to a Cloud SQL database
-db = init_connection_pool()
-# creates required 'votes' table in database (if it does not exist)
-migrate_db(db)
+# lazy global initialization
+# db connection must be established within request context
+db = None
 
 
 @functions_framework.http
@@ -36,6 +35,13 @@ def votes(request: Request) -> Response:
     Returns:
         Flask HTTP Response to the client.
     """
+    global db
+    # initialize db within request context
+    if not db:
+        # initiate a connection pool to a Cloud SQL database
+        db = init_connection_pool()
+        # creates required 'votes' table in database (if it does not exist)
+        migrate_db(db)
     if request.method == "GET":
         context = get_index_context(db)
         return render_template("index.html", **context)
diff --git a/cloud-sql/postgres/sqlalchemy/main.py b/cloud-sql/postgres/sqlalchemy/main.py
@@ -20,14 +20,20 @@
 
 ############ TABS vs. SPACES App for Cloud Functions ############
 
-# initiate a connection pool to a Cloud SQL database
-db = init_connection_pool()
-# creates required 'votes' table in database (if it does not exist)
-migrate_db(db)
+# lazy global initialization
+# db connection must be established within request context
+db = None
 
 
 @functions_framework.http
 def votes(request: Request) -> Response:
+    global db
+    # initialize db within request context
+    if not db:
+        # initiate a connection pool to a Cloud SQL database
+        db = init_connection_pool()
+        # creates required 'votes' table in database (if it does not exist)
+        migrate_db(db)
     if request.method == "GET":
         context = get_index_context(db)
         return render_template("index.html", **context)
diff --git a/cloud-sql/sql-server/sqlalchemy/main.py b/cloud-sql/sql-server/sqlalchemy/main.py
@@ -12,22 +12,28 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from flask import render_template, Response
+from flask import render_template, Request, Response
 
 import functions_framework
 
 from app import get_index_context, init_connection_pool, migrate_db, save_vote
 
 ############ TABS vs. SPACES App for Cloud Functions ############
 
-# initiate a connection pool to a Cloud SQL database
-db = init_connection_pool()
-# creates required 'votes' table in database (if it does not exist)
-migrate_db(db)
+# lazy global initialization
+# db connection must be established within request context
+db = None
 
 
 @functions_framework.http
-def votes(request):
+def votes(request: Request) -> Response:
+    global db
+    # initialize db within request context
+    if not db:
+        # initiate a connection pool to a Cloud SQL database
+        db = init_connection_pool()
+        # creates required 'votes' table in database (if it does not exist)
+        migrate_db(db)
     if request.method == "GET":
         context = get_index_context(db)
         return render_template("index.html", **context)
