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authorJames Taylor <user234683@users.noreply.github.com>2019-02-25 20:47:49 -0800
committerJames Taylor <user234683@users.noreply.github.com>2019-02-25 20:47:49 -0800
commit1e1f55c9e5d98ba076bc67e7abe9e4d77d84c65b (patch)
tree56eeabd9f7f0813c4b02f03f865d7cae35277d29 /python/urllib3/contrib/appengine.py
parentb32330be4f15dd044e6212f526e52375f0a0f6c2 (diff)
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+"""
+This module provides a pool manager that uses Google App Engine's
+`URLFetch Service <https://cloud.google.com/appengine/docs/python/urlfetch>`_.
+
+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 <https://cloud.google.com/appengine/docs/python/\
+urlfetch/#Python_Quotas_and_limits>`_ 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 :class:`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 :class:`~urllib3.PoolManager` by enabling sockets.
+ Sockets also have `limitations and restrictions
+ <https://cloud.google.com/appengine/docs/python/sockets/\
+ #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
+<https://cloud.google.com/appengine/docs/flexible/>`_, you can use the standard
+:class:`PoolManager` without any configuration or special environment variables.
+"""
+
+from __future__ import absolute_import
+import io
+import logging
+import warnings
+from ..packages.six.moves.urllib.parse import urljoin
+
+from ..exceptions import (
+ HTTPError,
+ HTTPWarning,
+ MaxRetryError,
+ ProtocolError,
+ TimeoutError,
+ SSLError
+)
+
+from ..request import RequestMethods
+from ..response import HTTPResponse
+from ..util.timeout import Timeout
+from ..util.retry import Retry
+from . import _appengine_environ
+
+try:
+ from google.appengine.api import urlfetch
+except ImportError:
+ urlfetch = None
+
+
+log = logging.getLogger(__name__)
+
+
+class AppEnginePlatformWarning(HTTPWarning):
+ pass
+
+
+class AppEnginePlatformError(HTTPError):
+ pass
+
+
+class AppEngineManager(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
+ <https://cloud.google.com/appengine/docs/python/urlfetch>`_.
+
+ Notably it will raise an :class:`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 megabtyes.
+ * If you use an unsupported request method such as OPTIONS.
+
+ Beyond those cases, it will raise normal urllib3 errors.
+ """
+
+ def __init__(self, headers=None, retries=None, validate_certificate=True,
+ urlfetch_retries=True):
+ if not urlfetch:
+ raise AppEnginePlatformError(
+ "URLFetch is not available in this environment.")
+
+ if is_prod_appengine_mvms():
+ raise AppEnginePlatformError(
+ "Use normal urllib3.PoolManager instead of AppEngineManager"
+ "on Managed VMs, as using URLFetch is not necessary in "
+ "this environment.")
+
+ warnings.warn(
+ "urllib3 is using URLFetch on Google App Engine sandbox instead "
+ "of sockets. To use sockets directly instead of URLFetch see "
+ "https://urllib3.readthedocs.io/en/latest/reference/urllib3.contrib.html.",
+ AppEnginePlatformWarning)
+
+ RequestMethods.__init__(self, headers)
+ self.validate_certificate = validate_certificate
+ self.urlfetch_retries = urlfetch_retries
+
+ self.retries = retries or Retry.DEFAULT
+
+ def __enter__(self):
+ return self
+
+ def __exit__(self, exc_type, exc_val, exc_tb):
+ # Return False to re-raise any potential exceptions
+ return False
+
+ def urlopen(self, method, url, body=None, headers=None,
+ retries=None, redirect=True, timeout=Timeout.DEFAULT_TIMEOUT,
+ **response_kw):
+
+ retries = self._get_retries(retries, redirect)
+
+ try:
+ follow_redirects = (
+ redirect and
+ retries.redirect != 0 and
+ retries.total)
+ response = urlfetch.fetch(
+ url,
+ payload=body,
+ method=method,
+ headers=headers or {},
+ allow_truncated=False,
+ follow_redirects=self.urlfetch_retries and follow_redirects,
+ deadline=self._get_absolute_timeout(timeout),
+ validate_certificate=self.validate_certificate,
+ )
+ except urlfetch.DeadlineExceededError as e:
+ raise TimeoutError(self, e)
+
+ except urlfetch.InvalidURLError as e:
+ if 'too large' in str(e):
+ raise AppEnginePlatformError(
+ "URLFetch request too large, URLFetch only "
+ "supports requests up to 10mb in size.", e)
+ raise ProtocolError(e)
+
+ except urlfetch.DownloadError as e:
+ if 'Too many redirects' in str(e):
+ raise MaxRetryError(self, url, reason=e)
+ raise ProtocolError(e)
+
+ except urlfetch.ResponseTooLargeError as e:
+ raise AppEnginePlatformError(
+ "URLFetch response too large, URLFetch only supports"
+ "responses up to 32mb in size.", e)
+
+ except urlfetch.SSLCertificateError as e:
+ raise SSLError(e)
+
+ except urlfetch.InvalidMethodError as e:
+ raise AppEnginePlatformError(
+ "URLFetch does not support method: %s" % method, e)
+
+ http_response = self._urlfetch_response_to_http_response(
+ response, retries=retries, **response_kw)
+
+ # Handle redirect?
+ redirect_location = redirect and http_response.get_redirect_location()
+ if redirect_location:
+ # Check for redirect response
+ if (self.urlfetch_retries and retries.raise_on_redirect):
+ raise MaxRetryError(self, url, "too many redirects")
+ else:
+ if http_response.status == 303:
+ method = 'GET'
+
+ try:
+ retries = retries.increment(method, url, response=http_response, _pool=self)
+ except MaxRetryError:
+ if retries.raise_on_redirect:
+ raise MaxRetryError(self, url, "too many redirects")
+ return http_response
+
+ retries.sleep_for_retry(http_response)
+ log.debug("Redirecting %s -> %s", url, redirect_location)
+ redirect_url = urljoin(url, redirect_location)
+ return self.urlopen(
+ method, redirect_url, body, headers,
+ retries=retries, redirect=redirect,
+ timeout=timeout, **response_kw)
+
+ # Check if we should retry the HTTP response.
+ has_retry_after = bool(http_response.getheader('Retry-After'))
+ if retries.is_retry(method, http_response.status, has_retry_after):
+ retries = retries.increment(
+ method, url, response=http_response, _pool=self)
+ log.debug("Retry: %s", url)
+ retries.sleep(http_response)
+ return self.urlopen(
+ method, url,
+ body=body, headers=headers,
+ retries=retries, redirect=redirect,
+ timeout=timeout, **response_kw)
+
+ return http_response
+
+ def _urlfetch_response_to_http_response(self, urlfetch_resp, **response_kw):
+
+ if is_prod_appengine():
+ # Production GAE handles deflate encoding automatically, but does
+ # not remove the encoding header.
+ content_encoding = urlfetch_resp.headers.get('content-encoding')
+
+ if content_encoding == 'deflate':
+ del urlfetch_resp.headers['content-encoding']
+
+ transfer_encoding = urlfetch_resp.headers.get('transfer-encoding')
+ # We have a full response's content,
+ # so let's make sure we don't report ourselves as chunked data.
+ if transfer_encoding == 'chunked':
+ encodings = transfer_encoding.split(",")
+ encodings.remove('chunked')
+ urlfetch_resp.headers['transfer-encoding'] = ','.join(encodings)
+
+ original_response = HTTPResponse(
+ # In order for decoding to work, we must present the content as
+ # a file-like object.
+ body=io.BytesIO(urlfetch_resp.content),
+ msg=urlfetch_resp.header_msg,
+ headers=urlfetch_resp.headers,
+ status=urlfetch_resp.status_code,
+ **response_kw
+ )
+
+ return HTTPResponse(
+ body=io.BytesIO(urlfetch_resp.content),
+ headers=urlfetch_resp.headers,
+ status=urlfetch_resp.status_code,
+ original_response=original_response,
+ **response_kw
+ )
+
+ def _get_absolute_timeout(self, timeout):
+ if timeout is Timeout.DEFAULT_TIMEOUT:
+ return None # Defer to URLFetch's default.
+ if isinstance(timeout, Timeout):
+ if timeout._read is not None or timeout._connect is not None:
+ warnings.warn(
+ "URLFetch does not support granular timeout settings, "
+ "reverting to total or default URLFetch timeout.",
+ AppEnginePlatformWarning)
+ return timeout.total
+ return timeout
+
+ def _get_retries(self, retries, redirect):
+ if not isinstance(retries, Retry):
+ retries = Retry.from_int(
+ retries, redirect=redirect, default=self.retries)
+
+ if retries.connect or retries.read or retries.redirect:
+ warnings.warn(
+ "URLFetch only supports total retries and does not "
+ "recognize connect, read, or redirect retry parameters.",
+ AppEnginePlatformWarning)
+
+ return retries
+
+
+# Alias methods from _appengine_environ to maintain public API interface.
+
+is_appengine = _appengine_environ.is_appengine
+is_appengine_sandbox = _appengine_environ.is_appengine_sandbox
+is_local_appengine = _appengine_environ.is_local_appengine
+is_prod_appengine = _appengine_environ.is_prod_appengine
+is_prod_appengine_mvms = _appengine_environ.is_prod_appengine_mvms