Flask On Google App Engine

Create a Google Cloud Project (Remember the Project ID).

Install Google Cloud SDK. You can also use SDK for App Engine (Choose Standard environment and Python).

Create a directory for your project.

mkdir flask-appcd flask-app

Install Flask libraries

For Google App Engine Standard Environment, it's recommended to use Pyhon2.7.

Create requirements.txt with the following content.

# Latest version: https://pypi.python.org/pypi/Flask
# Prevent ImportError: cannot import name SpooledTemporaryFile

It's recommended to create a virtualenv for the python libraries used in this project. Optionally, you could use virtualenvwrapper as well.

Install virtualenv and create a virtualenv named env.

sudo pip install virtualenvvirtualenv env 

Activate env.

source env/bin/activate

Install flask and dependencies into lib directory.

pip install -t lib -r requirements.txt

Deactivate env.


Create appengine_config.py. The following code will include the lib folder as vendor libraries.

from google.appengine.ext import vendorvendor.add('lib')

Create Flask application

Make a directory to create flask application.

mkdir appcd app

Create python file app/__init__.py.

from flask import Flask, render_template, requestapp = Flask(__name__)@app.route('/')def home():    return render_template('home.html')

Create directory app/templates.

mkdir templatescd templates

Create template file app/templates/home.html.

<html>  <head>    <title>My Flask App</title>    <link rel="stylesheet" type="text/css" href="/static/css/style.css">  </head>  <body>    <h1>Hello</h1>    <div>My Flask App</div>  </body></html>

Create a static directory at project directory for css styles and other static assets.

cd ..cd ..mkdir staticcd staticmkdir csscd css

Create static/css/style.css.

h1 {  color: red;}

Configure app.yaml

Create app.yaml.

runtime: python27api_version: 1threadsafe: truehandlers:- url: /static  static_dir: static- url: /.*  script: app.app

Project directory structure

├── app
│   ├── templates
│   │   └── home.html
│   └── __init__.py
├── env
├── lib
├── static
│   └── css
│       └── style.css
├── appengine_config.py
├── app.yaml
└── requirements.txt

Test the application

Use dev_appserver.py to test the application on localhost. You shall be promopted to download and install the component if it is not available.

dev_appserver.py app.yaml

By default it shall run on port 8080, you can change the port with --port parameter.

dev_appserver.py --port 8088 app.yaml

Note: if you bump into ImportError: cannot import name SpooledTemporaryFile, you need downgrade werkzeug to 0.12.2 by executing pip install --target lib --upgrade werkzeug==0.12.2. Reference.

ImportError: cannot import name SpooledTemporaryFile


Use gcloud app deploy for deployment, specifiying the project and version is recommended.

gcloud app deploy --project <PROJECT_ID> -v 1

If you bump into the following error, run gcloud app create to initialize App Engine application.

The current Google Cloud project PROJECT_ID does not contain an App Engine application. Use gcloud app create to initialize an App Engine application within the project., you need to run the following command.

gcloud app create --project <PROJECT_ID>

You can view your website at https://<PROJECT_ID>.appspot.com.


❤️ Is this article helpful?

Buy me a coffee ☕ or support my work via PayPal to keep this space 🖖 and ad-free.

Do send some 💖 to @d_luaz or share this article.

✨ By Desmond Lua

A dream boy who enjoys making apps, travelling and making youtube videos. Follow me on @d_luaz

👶 Apps I built

Travelopy - discover travel places in Malaysia, Singapore, Taiwan, Japan.