Google App Engine applications are easy to create, easy to maintain, and easy to scale as your traffic and data storage needs change. With App Engine, there are no servers to maintain. You simply upload your application and it's ready to go.

App Engine applications automatically scale based on incoming traffic. Load balancing, microservices, authorization, SQL and noSQL databases, memcache, traffic splitting, logging, search, versioning, roll out and roll backs, and security scanning are all supported natively and are highly customizable.

App Engine's environments, the Standard Environment and the Flexible environment, support a host of programming languages, including Java, Python, PHP, NodeJS, Go, etc.. The two environments give users maximum flexibility in how their application behaves since each environment has certain strengths. Read The App Engine Environments for more information.

In this codelab, you will learn how to to connect to computing resources hosted on Google Cloud Platform via the web. You will learn how to use Cloud Shell and the Cloud SDK gcloud command.

This tutorial is adapted from https://cloud.google.com/appengine/docs/python/

What you'll learn

What you'll need

How will you use use this tutorial?

Read it through only Read it and complete the exercises

How would you rate your experience with building HTML/CSS web apps?

Novice Intermediate Proficient

How would you rate your experience with using Google Cloud Platform services?

Novice Intermediate Proficient

Codelab-at-a-conference setup

The instructor will be sharing with you temporary accounts with existing projects that are already setup so you do not need to worry about enabling billing or any cost associated with running this codelab. Note that all these accounts will be disabled soon after the codelab is over.

Once you have received a temporary username / password to login from the instructor, log into Google Cloud Console: https://console.cloud.google.com/.

Here's what you should see once logged in :

Note the project ID you were assigned ( "codelab-test003" in the screenshot above). It will be referred to later in this codelab as PROJECT_ID.

Google Cloud Shell

While Google Cloud and Kubernetes can be operated remotely from your laptop, in this codelab we will be using Google Cloud Shell, a command line environment running in the Cloud. This Debian-based virtual machine is loaded with all the development tools you'll need (docker, gcloud, kubectl and more), it offers a persistent 5GB home directory, and runs on the Google Cloud, greatly enhancing network performance and authentication. This means that all you will need for this codelab is a browser (yes, it works on a Chromebook).

To activate Google Cloud Shell, from the developer console simply click the button on the top right-hand side (it should only take a few moments to provision and connect to the environment):

Once connected to the cloud shell, you should see that you are already authenticated and that the project is already set to your PROJECT_ID :

$ gcloud auth list
Credentialed accounts:
 - <myaccount>@<mydomain>.com (active)
$ gcloud config list project
[core]
project = <PROJECT_ID>

If for some reason the project is not set, simply issue the following command :

$ gcloud config set project <PROJECT_ID>

Looking for you PROJECT_ID? Check out what ID you used in the setup steps or look it up in the console dashboard :

IMPORTANT. Finally, set the default zone and project configuration:

$ gcloud config set compute/zone us-central1-f
$ gcloud config set compute/region us-central1

You can pick and choose different zones too. Learn more about zones in Regions & Zones documentation.

Navigate to the the Google Cloud Console from another browser tab/window, to https://console.cloud.google.com. Use the login credential given to you by the lab proctor.

You will do all of the work from the Google Cloud Shell, a command line environment running in the Cloud. This Debian-based virtual machine is loaded with all the development tools you'll need (gcloud, git and others) and offers a persistent 5GB home directory. Open the Google Cloud Shell by clicking on the icon on the top right of the screen:

After Cloud Shell launches, you can use the command line to invoke the Cloud SDK gcloud command or other tools available on the virtual machine instance. You can use your $HOME directory in persistent disk storage to store files across projects and between Cloud Shell sessions. Your $HOME directory is private to you and cannot be accessed by other users.

Let's get started by creating a new folder in your $HOME directory for the application:

$ mkdir helloworld && cd helloworld

Inside the helloworld directory, create a file named helloworld.py, and give it the following contents:

helloworld.py

import webapp2

class MainPage(webapp2.RequestHandler):
    def get(self):
        self.response.headers['Content-Type'] = 'text/plain'
        self.response.write('Hello, World!')

app = webapp2.WSGIApplication([
    ('/', MainPage),
], debug=True)

This Python script responds to a request with an HTTP header that describes the content and the message Hello, World!.

An App Engine application has a configuration file called app.yaml. Among other things, this file describes which handler scripts should be used for which URLs.

Inside the helloworld directory, create a file named app.yaml with the following contents:

app.yaml

runtime: python27
api_version: 1
threadsafe: true

handlers:
- url: /.*
  script: helloworld.app

From top to bottom, this configuration file says the following about this application:

The syntax of this file is YAML. For a complete list of configuration options, see the app.yaml reference.

Start a deployment instance of the application server:

$ dev_appserver.py ./

Click on the Web Preview icon in the Cloud Shell toolbar and choose "preview on port 8080:. A tab in your browser opens and connects to the server you just started.

You can leave the web server running while you develop your application. The web server knows to watch for changes in your source files and reload them if necessary.

Try it now: Leave the web server running, and add a new Cloud Shell terminal by clicking the + sign.

Go back to your helloworld directory:

$ cd helloworld

Now, edit helloworld.py to change Hello, World! to something else e.g. "Hello, Kathy!".

helloworld.py

import webapp2

class MainPage(webapp2.RequestHandler):
    def get(self):
        self.response.headers['Content-Type'] = 'text/plain'
        self.response.write('Hello, Kathy!')

app = webapp2.WSGIApplication([
    ('/', MainPage),
], debug=True)

Reload the tab in the browser in which the app is running.

Deploy your Hello World server to the production App Engine environment:

$ gcloud app deploy app.yaml

After the application is deployed, you can visit it by opening the URL http://<project-id>.appspot.com in your web browser.

The full URL for your application is http://_your-app-id_.appspot.com/. Optionally, you can instead purchase and use a top-level domain name for your app, or use one that you have already registered.

Summary

In this step, you set up a simple Python application and ran and deployed your application on App Engine.

You learned how to write your first App Engine web application!

Learn More

License

This work is licensed under a Creative Commons Attribution 2.0 Generic License.