NDB GAE App on Localhost
Test Google Cloud NDB apps locally with Firestore emulator. Complete Flask setup with Makefile and Datastore mode configuration. Deploy to Cloud Run with confidence.
If you want to test a Google Cloud NDB app locally before pushing it to Cloud Run, you can wire it up with the Firestore emulator (in Datastore mode). Here’s a minimal setup.
Project Layout
app/
main.py
models.py
templates/index.html
requirements.txt
MakefileRequirements
# requirements.txt
Flask==3.0.3
google-cloud-ndb==2.2.2Models
# models.py
from google.cloud import ndb
class Counter(ndb.Model):
value = ndb.IntegerProperty(default=0)App
# main.py
import os
from flask import Flask, render_template
from google.cloud import ndb
from models import Counter
app = Flask(__name__)
# NDB client setup
def get_client():
project_id = os.getenv("DATASTORE_PROJECT_ID", "demo-project")
return ndb.Client(project=project_id)
@app.route("/")
def index():
client = get_client()
with client.context():
counter = Counter.get_by_id("main")
if not counter:
counter = Counter(id="main", value=0)
counter.value += 1
counter.put()
return render_template("index.html", count=counter.value)
if __name__ == "__main__":
app.run(host="0.0.0.0", port=8081, debug=True)
HTML Template
<!-- templates/index.html -->
<!doctype html>
<html>
<body>
<h1>Counter Value: {{ count }}</h1>
</body>
</html>Makefile
PROJECT_ID=demo-project
DATASTORE_EMULATOR_HOST_PORT=localhost:8082
PYTHON3=.venv/bin/python3
run_emulator:
gcloud beta emulators firestore start \
--host-port=$(DATASTORE_EMULATOR_HOST_PORT) \
--project=$(PROJECT_ID) \
--database-mode=datastore-mode
run_app:
DATASTORE_PROJECT_ID=$(PROJECT_ID) \
DATASTORE_EMULATOR_HOST=$(DATASTORE_EMULATOR_HOST_PORT) \
FLASK_ENV=development \
$(PYTHON3) main.py
install:
python3 -m venv .venv
.venv/bin/pip install -r requirements.txtRunning the App
- Start the emulator:
make run_emulator- In another terminal, run the app:
make run_app- Visit http://localhost:8081. Each refresh increments the counter.
That’s it: a tiny Flask + NDB app, backed by the Firestore emulator in Datastore mode. Ready to push to Cloud Run later.
End Result
