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Diffstat (limited to 'python/urllib3/contrib/appengine.py')
| -rw-r--r-- | python/urllib3/contrib/appengine.py | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/python/urllib3/contrib/appengine.py b/python/urllib3/contrib/appengine.py new file mode 100644 index 0000000..2952f11 --- /dev/null +++ b/python/urllib3/contrib/appengine.py @@ -0,0 +1,289 @@ +""" +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 |