There are lot of resources available in the web and therefore it is not a necessary to write about it. So I'm directly writing down what are the things I learned today by exploring Google App Engine. First of all I downloaded the Google App Engine SDK from here. Since I'm using Linux, I downloaded the version for the Linux platform which comes as a Zipped archive.
After uncompressing the Zipped folder, we can see different Python based tools available on this source code. So, now I'm writing a simple program which prints some text on the web browser.
1) Create a new directory in some where in the file system. Say we created it in desktop naming as my-application.
mkdir my-application
2. Now create a file named as app.yaml inside that directory and add the following content to it. Please note that application name is given as my-application. You have to give a unique name for this application.
application: my-application
version: 1
runtime: python27
api_version: 1
threadsafe: yes
handlers:
- url: .*
script: helloworld.app
libraries:
- name: webapp2
version: "2.5.1"
3. Now create another file named as helloworld.py which will contain the codes of our application. Add the following content to that file.
#!/usr/bin/env python
import cgi
import datetime
import webapp2
class MainPage(webapp2.RequestHandler):
def get(self):
self.response.out.write('<html><body><h4>My First Google App Engine Application</h4>')
self.response.out.write('</body></html>')
app = webapp2.WSGIApplication([
('/', MainPage)
], debug=True)
4. Now our source codes are ready. We have to test this app. Google App Engine SDK comes with a server which can be used to test our application before actually deploying the application on Google cloud. To use this server, go into the uncompressed Google App Engine SDK source folder. There's a tool named as dev_appserver.py. Run this python script giving the path to our new application as follows.
python dev_appserver.py /path/to/my-application
Then this server will start. Now open a web browser and go to the following URL.
http://localhost:8080/
The text "My First Google App Engine Application" will be printed on the browser. That means our application is ready.
5. Now we can try deploying our simple app on the Google cloud. To do that we have to go to the this URL (https://appengine.google.com/) and sign in. Then click on the "Create Application" button. As the application identifier you have to give a unique name for the application. This name should be defined as the application name in app.yaml file. For example we might use my-application as the name if nobody has used that name for an application on Google App Engine.
The give some Application title and then click on "Create Application" button. Now google is ready to host our application.
6. To upload our application codes to the Google cloud, we can use appcfg.py tool which also came with the Google App Engine SDK. We run it giving the path to our application as follows.
python appcfg.py update /path/to/my-application
After this tool completes running your application is gone to the Google cloud. You can see it from the appspot.com domain name with the application name in front of it. For example if the application name is my-application then you can access your app by typing the following URL on the web browsers address bar.
http://my-application.appspot.com/
If every thing is fine, you will see the text "My First Google App Engine Application" on the web browser again.
