I recently came across Flask, a nice tiny Python micro-web-framework.
I took the ‘hello world’ sample from the Flask website, which I wanted to host/run on Google App Engine (GAE).
Here are the necessary steps for the “Flask Hello World on App Engine”:
The python source File (pineapple.py in this example):
from flask import Flask app = Flask(__name__) @app.route('/') def hello_world(): return 'Hello World!'
An app.yaml for the Google App Engine:
This is straightforward, but I want to use jinja2 (a requirement for Flask) lib from GAE, so I added the libraries section
application: flaskpineapple version: 1 runtime: python27 api_version: 1 threadsafe: true libraries: - name: jinja2 version: "2.6" handlers: - url: /.* script: pineapple.app
Unfortunately there are no libs for Flask available in GAE (yet?), so I had to include them in the app (which is the GAE way to do that). The same is necessary for Flask’s dependencies “werkzeug” and “itsdangerous“. This is simply done by copying the Modules/Files into the application directory
λ ls -al drwxr-xr-x 17 Daniel Adm 4096 Jun 3 11:01 . drwxr-xr-x 1 Daniel Adm 0 Jun 3 10:49 .. -rw-r--r-- 1 Daniel Adm 194 Jun 3 10:44 app.yaml drwxr-xr-x 38 Daniel Adm 8192 Jun 3 10:43 flask -rw-r--r-- 1 Daniel Adm 31840 May 30 17:19 itsdangerous.py -rw-r--r-- 1 Daniel Adm 165 Jun 3 10:46 pineapple.py drwxr-xr-x 39 Daniel Adm 8192 Jun 3 10:44 werkzeug
That’s all! A simple “Hello World” with Flask and GAE.