App Engine & Earth Engine Overview

Google App Engine lets you build and run your own custom applications on Google’s servers. App Engine applications are easy to create, maintain, and scale as your traffic and data storage needs change. You simply upload your application source code and it’s ready to go. If you're new to developing for App Engine, be sure to check out the App Engine Python quickstart before proceeding.

Earth Engine and App Engine can be used together to build scalable geospatial applications. Typically, your App Engine code includes the Earth Engine Python client library and makes requests to the Earth Engine backend using a service account. This is advantageous because it allows anyone to use your app without logging in or being a registered Earth Engine user. Note that the standard Earth Engine usage limits apply to each service account. If you expect your application to be popular and approach the usage limits, please contact the Earth Engine team (earthengine@google.com) before launching the application.

Another development approach is to use client-side authentication instead of a service account. With this approach, visitors to your application must be whitelisted for Earth Engine and log in. The benefit of this approach is that requests to Earth Engine are made using the end user's credentials, so you are less likely to hit usage limits. The challenge is that your users must signup for Earth Engine and log in before using the application.

The Earth Engine App Engine demos directory on GitHub contains a set of useful App Engine examples. See the Example Apps page for a brief description of each example. This doc provides instructions for how to set up and deploy the examples or custom apps you create.

Deploying App Engine apps with Earth Engine

The following instructions explain how to deploy the demo apps on Mac OS and Linux. If you're on Windows, try this.

1. Create your own project

Each App Engine app needs its own project. To deploy your own instance, you'll need to have a project with a unique ID (e.g. foo-ee-project). This guide assumes that you will create a new project.

To create an App Engine project for your app:

  1. Use the Google Cloud Console to create a new project. (You may need to accept the terms of service as part of this process.)
  2. Enter a project name. (Note that the project name is distinct from the project ID. The project ID is based on the name by default, but you can edit the ID independently of the name by clicking Edit.)
  3. Click CREATE.
  4. If prompted, choose a region close to the users for your app.

2. Set up credentials

Service account

A service account is used to authorize requests to Earth Engine on behalf of whomever is using your app. The config.py file contains authentication code using the service account email address and a private key file. To set up authentication with a service account:

  1. Create and authorize a service account.
  2. Download a private key file associated with your app's service account and move it into your project directory. Rename the key file privatekey.json
  3. Update config.py (or an equivalent file in your source code) with your service account email address. (The path to the key file should not change since it's in your project directory).
  4. Test the service account authentication flow by running the following commands from the Python command line (this assumes you have already installed the Earth Engine Python API).
    service_account = 'my-service-account-id@...gserviceaccount.com'
    credentials = ee.ServiceAccountCredentials(service_account, 'privatekey.json')
    ee.Initialize(credentials)
    

OAuth 2.0 Client ID

If you want users to authenticate as themselves (rather than using a service account), you need to set up an OAuth Client ID. To do that:

  1. From the menu in the upper left of the Developers Console, choose APIs & Services > Credentials. Click Create credentials > OAuth client ID and select Web application.
  2. In the configuration of the web application, specify authorized JavaScript origins, for example:
    http://localhost:8080
    https://foo-ee-project.appspot.com
    
  3. Specify authorized redirect URIs, for example:
    http://localhost:8080/oauth2callback
    https://foo-ee-project.appspot.com/oauth2callback
    
  4. Update static/script.js (or an equivalent file in your source code) to use your client ID.
  5. Ensure ee_api_js.js is available in the /static/ directory (or equivalent). You can download it directly from GitHub or, if you've already cloned the entire EE API repo, copy it from earthengine-api/javascript/build on your local filesystem.

Check out the Google Identity OAuth documentation for a more detailed explanation of OAuth.

3. Set up the local development environment

Follow the instructions in each example directory on GitHub to download and build the project. If there's a build.sh file, run it from your application root folder with the command:

./build.sh

The setup script will download dependencies and install Google command line tools, if they don't already exist on your system. The Earth Engine Python API and its dependencies will be copied to a ./lib folder in your project directory.

Verify that the App Engine command line tools are available by running:

dev_appserver.py

If the command is not found, try manually downloading and installing the Google App Engine SDK for Python. If the command is available, it should fail with "error: too few arguments".

Also verify that the crypto library is installed with:

python -c "from oauth2client import crypt"

If an error is returned, install pyCrypto into your local Python distribution. For example, using pip:

sudo pip install pyCrypto

4. Run locally

Once your service account is whitelisted for Earth Engine access, you can use it to authenticate (see config.py) when you test the examples. Try testing the examples locally first by going into your project directory and running:

dev_appserver.py .

Point your browser to http://localhost:8080 to see the app running on a local server. Any changes you make (and save) will be automatically picked up when you refresh the page.

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