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# Google App Engine

This module provides a pool manager that uses Google App Engine’s URLFetch Service.

Example usage:

    from urllib3 import PoolManager
    from urllib3.contrib.appengine import AppEngineManager, is_appengine_sandbox

    if is_appengine_sandbox():
        # AppEngineManager uses AppEngine's URLFetch API behind the scenes
        http = AppEngineManager()
    else:
        # PoolManager uses a socket-level API behind the scenes
        http = PoolManager()

    r = http.request('GET', 'https://google.com/')

There are limitations to the URLFetch service and it may not be the best choice for your application. There are three options for using urllib3 on Google App Engine:

1. You can use `AppEngineManager` with URLFetch. URLFetch is cost-effective in many circumstances as long as your usage is within the limitations.

2. You can use a normal `PoolManager` by enabling sockets. Sockets also have limitations and restrictions and have a lower free quota than URLFetch. To use sockets, be sure to specify the following in your `app.yaml`:

       env_variables:
           GAE_USE_SOCKETS_HTTPLIB : 'true'

3. If you are using App Engine Flexible, you can use the standard `PoolManager` without any configuration or special environment variables.

class urllib3.contrib.appengine.AppEngineManager(headers=None, retries=None, validate_certificate=True, urlfetch_retries=True)

  Bases: `RequestMethods`

  Connection manager for Google App Engine sandbox applications.

  This manager uses the URLFetch service directly instead of using the emulated httplib, and is subject to URLFetch limitations as described in the App Engine documentation here.

  Notably it will raise an `AppEnginePlatformError` if:

    - URLFetch is not available.

    - If you attempt to use this on App Engine Flexible, as full socket support is available.

    - If a request size is more than 10 megabytes.

    - If a response size is more than 32 megabytes.

    - If you use an unsupported request method such as OPTIONS.

  Beyond those cases, it will raise normal urllib3 errors.

  urlopen(method, url, body=None, headers=None, retries=None, redirect=True, timeout=<object object>, **response_kw)

exception urllib3.contrib.appengine.AppEnginePlatformError

  Bases: `HTTPError`

exception urllib3.contrib.appengine.AppEnginePlatformWarning

  Bases: `HTTPWarning`