How to Create a Python App in Google Appengine

Step-by-Step Guide

1. 1

   Step 1: Set up your environment.

   Download and install Python
   2.7 for your platform, if you haven’t done so already (as of this writing, only
   2.5 and
   2.7 versions are supported) .
   
   Then, download and install the GAE API from here.
   
   MSI setups are available for windows platform.
   
   For Linux, you can just unzip into a local folder like ‘~/programs/’.
   
   The zip file will create a subdir called ‘google_appengine’.
   
   Practically, the only two Python scripts you are ever going to need to develop a GAE app are: dev_appserver.py and appcfg.py
2. 2

   Step 2: Register your app on appspot.com.

   Register your subdomain on GAE by visiting https://appengine.google.com.
   
   Once you register your app there, you will get a subdomain called http://your-app-id.appspot.com.
   
   There are also options for redirecting your custom domain such as www.mydomain.com to your app subdomain. , This is as simple as creating a folder on your machine such as ~/source/foo in linux or C:\source\foo in windows.
   
   Then just create a text file named app.yaml with below contents inside this folder. #application: your-app-id #version:1 #runtime: python27 #api_version: 1 #threadsafe: true #handlers: #- url: /.* #script: helloworld.application Note that your-app-id is the name that you just registered for yourself, make sure that it is typed correctly. version parameter refers to the version of your app, while api_version is the version of GAE SDK used to run this app.
   
   The line “script: helloworld.application” indicates that this wsgi handler will be invoked for your app. , This is as simple as creating a Python file named “helloworld.py” in the same folder as above, and add below contents to it. #import webapp2 #class MainPage(webapp2.RequestHandler): #def get(self): #self.response.headers= 'text/plain' #self.response.write('Hello, World!') #application =webapp2.WSGIApplication([ #('/'
   
   MainPage), ], debug=True) , To test your app, open up your terminal and change directory to your GAE installation folder (alternatively, add the GAE installation folder to your PATH/$PATH environment variable to avoid doing this each time), and then type the below command python dev_appserver.py ~/source/foo OR on Windows: python dev_appserver.py C:\source\foo , Want to host this app on GAE and check it out? Just fire up your terminal as described above and issue this command: python appcfg.py update ~/source/foo or on Windows: python appcfg.py update C:\source\foo Test your app:
   The above command should host your app on your appspot subdomain (it will ask for your Google username/password before doing so).
   
   Once the app is successfully hosted, you can check it out by visiting http://your-app-id.appspot.com. , Now that you have a working app, you can actually visit the official reference to read more about: webapp2:
   The Python web framework used to handle requests and generate responses.
   
   Datastore:
   The big data storage feature that GAE provides your app to store its data.
   
   Quotas and Limits:
   Learn about the various limits that google sets for your app to access resources (Don’t worry, they are enough to suffice a small to medium scale app).
   
   App caching:
   Learn how to take advantage of various caching mechanisms in GAE to speed up your app.
3. 3

   Step 3: Create your app on the local machine.

4. 4

   Step 4: Create the wsgi handler.

5. 5

   Step 5: Test your app.

6. 6

   Step 6: Deploy your app.

7. 7

   Step 7: Do some further reading.

Detailed Guide

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