Edit File: url_helper.py
# Copyright (C) 2012 Canonical Ltd. # Copyright (C) 2012 Hewlett-Packard Development Company, L.P. # Copyright (C) 2012 Yahoo! Inc. # # Author: Scott Moser <scott.moser@canonical.com> # Author: Juerg Haefliger <juerg.haefliger@hp.com> # Author: Joshua Harlow <harlowja@yahoo-inc.com> # # This file is part of cloud-init. See LICENSE file for license information. import copy import json import os import requests import six import time from email.utils import parsedate from errno import ENOENT from functools import partial from itertools import count from requests import exceptions from six.moves.urllib.parse import ( urlparse, urlunparse, quote as urlquote) from cloudinit import log as logging from cloudinit import version LOG = logging.getLogger(__name__) if six.PY2: import httplib NOT_FOUND = httplib.NOT_FOUND else: import http.client NOT_FOUND = http.client.NOT_FOUND # Check if requests has ssl support (added in requests >= 0.8.8) SSL_ENABLED = False CONFIG_ENABLED = False # This was added in 0.7 (but taken out in >=1.0) _REQ_VER = None REDACTED = 'REDACTED' try: from distutils.version import LooseVersion import pkg_resources _REQ = pkg_resources.get_distribution('requests') _REQ_VER = LooseVersion(_REQ.version) # pylint: disable=no-member if _REQ_VER >= LooseVersion('0.8.8'): SSL_ENABLED = True if LooseVersion('0.7.0') <= _REQ_VER < LooseVersion('1.0.0'): CONFIG_ENABLED = True except ImportError: pass def _cleanurl(url): parsed_url = list(urlparse(url, scheme='http')) if not parsed_url[1] and parsed_url[2]: # Swap these since this seems to be a common # occurrence when given urls like 'www.google.com' parsed_url[1] = parsed_url[2] parsed_url[2] = '' return urlunparse(parsed_url) def combine_url(base, *add_ons): def combine_single(url, add_on): url_parsed = list(urlparse(url)) path = url_parsed[2] if path and not path.endswith("/"): path += "/" path += urlquote(str(add_on), safe="/:") url_parsed[2] = path return urlunparse(url_parsed) url = base for add_on in add_ons: url = combine_single(url, add_on) return url def read_file_or_url(url, **kwargs): """Wrapper function around readurl to allow passing a file path as url. When url is not a local file path, passthrough any kwargs to readurl. In the case of parameter passthrough to readurl, default values for some parameters. See: call-signature of readurl in this module for param docs. """ url = url.lstrip() if url.startswith("/"): url = "file://%s" % url if url.lower().startswith("file://"): if kwargs.get("data"): LOG.warning("Unable to post data to file resource %s", url) file_path = url[len("file://"):] try: with open(file_path, "rb") as fp: contents = fp.read() except IOError as e: code = e.errno if e.errno == ENOENT: code = NOT_FOUND raise UrlError(cause=e, code=code, headers=None, url=url) return FileResponse(file_path, contents=contents) else: return readurl(url, **kwargs) # Made to have same accessors as UrlResponse so that the # read_file_or_url can return this or that object and the # 'user' of those objects will not need to know the difference. class StringResponse(object): def __init__(self, contents, code=200): self.code = code self.headers = {} self.contents = contents self.url = None def ok(self, *args, **kwargs): if self.code != 200: return False return True def __str__(self): return self.contents.decode('utf-8') class FileResponse(StringResponse): def __init__(self, path, contents, code=200): StringResponse.__init__(self, contents, code=code) self.url = path class UrlResponse(object): def __init__(self, response): self._response = response @property def contents(self): return self._response.content @property def url(self): return self._response.url def ok(self, redirects_ok=False): upper = 300 if redirects_ok: upper = 400 if 200 <= self.code < upper: return True else: return False @property def headers(self): return self._response.headers @property def code(self): return self._response.status_code def __str__(self): return self._response.text class UrlError(IOError): def __init__(self, cause, code=None, headers=None, url=None): IOError.__init__(self, str(cause)) self.cause = cause self.code = code self.headers = headers if self.headers is None: self.headers = {} self.url = url def _get_ssl_args(url, ssl_details): ssl_args = {} scheme = urlparse(url).scheme if scheme == 'https' and ssl_details: if not SSL_ENABLED: LOG.warning("SSL is not supported in requests v%s, " "cert. verification can not occur!", _REQ_VER) else: if 'ca_certs' in ssl_details and ssl_details['ca_certs']: ssl_args['verify'] = ssl_details['ca_certs'] else: ssl_args['verify'] = True if 'cert_file' in ssl_details and 'key_file' in ssl_details: ssl_args['cert'] = [ssl_details['cert_file'], ssl_details['key_file']] elif 'cert_file' in ssl_details: ssl_args['cert'] = str(ssl_details['cert_file']) return ssl_args def readurl(url, data=None, timeout=None, retries=0, sec_between=1, headers=None, headers_cb=None, headers_redact=None, ssl_details=None, check_status=True, allow_redirects=True, exception_cb=None, session=None, infinite=False, log_req_resp=True, request_method=None): """Wrapper around requests.Session to read the url and retry if necessary :param url: Mandatory url to request. :param data: Optional form data to post the URL. Will set request_method to 'POST' if present. :param timeout: Timeout in seconds to wait for a response :param retries: Number of times to retry on exception if exception_cb is None or exception_cb returns True for the exception caught. Default is to fail with 0 retries on exception. :param sec_between: Default 1: amount of seconds passed to time.sleep between retries. None or -1 means don't sleep. :param headers: Optional dict of headers to send during request :param headers_cb: Optional callable returning a dict of values to send as headers during request :param headers_redact: Optional list of header names to redact from the log :param ssl_details: Optional dict providing key_file, ca_certs, and cert_file keys for use on in ssl connections. :param check_status: Optional boolean set True to raise when HTTPError occurs. Default: True. :param allow_redirects: Optional boolean passed straight to Session.request as 'allow_redirects'. Default: True. :param exception_cb: Optional callable which accepts the params msg and exception and returns a boolean True if retries are permitted. :param session: Optional exiting requests.Session instance to reuse. :param infinite: Bool, set True to retry indefinitely. Default: False. :param log_req_resp: Set False to turn off verbose debug messages. :param request_method: String passed as 'method' to Session.request. Typically GET, or POST. Default: POST if data is provided, GET otherwise. """ url = _cleanurl(url) req_args = { 'url': url, } req_args.update(_get_ssl_args(url, ssl_details)) req_args['allow_redirects'] = allow_redirects if not request_method: request_method = 'POST' if data else 'GET' req_args['method'] = request_method if timeout is not None: req_args['timeout'] = max(float(timeout), 0) if headers_redact is None: headers_redact = [] # It doesn't seem like config # was added in older library versions (or newer ones either), thus we # need to manually do the retries if it wasn't... if CONFIG_ENABLED: req_config = { 'store_cookies': False, } # Don't use the retry support built-in # since it doesn't allow for 'sleep_times' # in between tries.... # if retries: # req_config['max_retries'] = max(int(retries), 0) req_args['config'] = req_config manual_tries = 1 if retries: manual_tries = max(int(retries) + 1, 1) def_headers = { 'User-Agent': 'Cloud-Init/%s' % (version.version_string()), } if headers: def_headers.update(headers) headers = def_headers if not headers_cb: def _cb(url): return headers headers_cb = _cb if data: req_args['data'] = data if sec_between is None: sec_between = -1 excps = [] # Handle retrying ourselves since the built-in support # doesn't handle sleeping between tries... # Infinitely retry if infinite is True for i in count() if infinite else range(0, manual_tries): req_args['headers'] = headers_cb(url) filtered_req_args = {} for (k, v) in req_args.items(): if k == 'data': continue if k == 'headers' and headers_redact: matched_headers = [k for k in headers_redact if v.get(k)] if matched_headers: filtered_req_args[k] = copy.deepcopy(v) for key in matched_headers: filtered_req_args[k][key] = REDACTED else: filtered_req_args[k] = v try: if log_req_resp: LOG.debug("[%s/%s] open '%s' with %s configuration", i, "infinite" if infinite else manual_tries, url, filtered_req_args) if session is None: session = requests.Session() with session as sess: r = sess.request(**req_args) if check_status: r.raise_for_status() LOG.debug("Read from %s (%s, %sb) after %s attempts", url, r.status_code, len(r.content), (i + 1)) # Doesn't seem like we can make it use a different # subclass for responses, so add our own backward-compat # attrs return UrlResponse(r) except exceptions.RequestException as e: if (isinstance(e, (exceptions.HTTPError)) and hasattr(e, 'response') and # This appeared in v 0.10.8 hasattr(e.response, 'status_code')): excps.append(UrlError(e, code=e.response.status_code, headers=e.response.headers, url=url)) else: excps.append(UrlError(e, url=url)) if SSL_ENABLED and isinstance(e, exceptions.SSLError): # ssl exceptions are not going to get fixed by waiting a # few seconds break if exception_cb and not exception_cb(req_args.copy(), excps[-1]): # if an exception callback was given, it should return True # to continue retrying and False to break and re-raise the # exception break if (infinite and sec_between > 0) or \ (i + 1 < manual_tries and sec_between > 0): if log_req_resp: LOG.debug( "Please wait %s seconds while we wait to try again", sec_between) time.sleep(sec_between) if excps: raise excps[-1] return None # Should throw before this... def wait_for_url(urls, max_wait=None, timeout=None, status_cb=None, headers_cb=None, headers_redact=None, sleep_time=1, exception_cb=None, sleep_time_cb=None, request_method=None): """ urls: a list of urls to try max_wait: roughly the maximum time to wait before giving up The max time is *actually* len(urls)*timeout as each url will be tried once and given the timeout provided. a number <= 0 will always result in only one try timeout: the timeout provided to urlopen status_cb: call method with string message when a url is not available headers_cb: call method with single argument of url to get headers for request. headers_redact: a list of header names to redact from the log exception_cb: call method with 2 arguments 'msg' (per status_cb) and 'exception', the exception that occurred. sleep_time_cb: call method with 2 arguments (response, loop_n) that generates the next sleep time. request_method: indicate the type of HTTP request, GET, PUT, or POST returns: tuple of (url, response contents), on failure, (False, None) the idea of this routine is to wait for the EC2 metadata service to come up. On both Eucalyptus and EC2 we have seen the case where the instance hit the MD before the MD service was up. EC2 seems to have permanently fixed this, though. In openstack, the metadata service might be painfully slow, and unable to avoid hitting a timeout of even up to 10 seconds or more (LP: #894279) for a simple GET. Offset those needs with the need to not hang forever (and block boot) on a system where cloud-init is configured to look for EC2 Metadata service but is not going to find one. It is possible that the instance data host (169.254.169.254) may be firewalled off Entirely for a system, meaning that the connection will block forever unless a timeout is set. A value of None for max_wait will retry indefinitely. """ start_time = time.time() def log_status_cb(msg, exc=None): LOG.debug(msg) if status_cb is None: status_cb = log_status_cb def timeup(max_wait, start_time): if (max_wait is None): return False return ((max_wait <= 0) or (time.time() - start_time > max_wait)) loop_n = 0 response = None while True: if sleep_time_cb is not None: sleep_time = sleep_time_cb(response, loop_n) else: sleep_time = int(loop_n / 5) + 1 for url in urls: now = time.time() if loop_n != 0: if timeup(max_wait, start_time): break if (max_wait is not None and timeout and (now + timeout > (start_time + max_wait))): # shorten timeout to not run way over max_time timeout = int((start_time + max_wait) - now) reason = "" url_exc = None try: if headers_cb is not None: headers = headers_cb(url) else: headers = {} response = readurl( url, headers=headers, headers_redact=headers_redact, timeout=timeout, check_status=False, request_method=request_method) if not response.contents: reason = "empty response [%s]" % (response.code) url_exc = UrlError(ValueError(reason), code=response.code, headers=response.headers, url=url) elif not response.ok(): reason = "bad status code [%s]" % (response.code) url_exc = UrlError(ValueError(reason), code=response.code, headers=response.headers, url=url) else: return url, response.contents except UrlError as e: reason = "request error [%s]" % e url_exc = e except Exception as e: reason = "unexpected error [%s]" % e url_exc = e time_taken = int(time.time() - start_time) max_wait_str = "%ss" % max_wait if max_wait else "unlimited" status_msg = "Calling '%s' failed [%s/%s]: %s" % (url, time_taken, max_wait_str, reason) status_cb(status_msg) if exception_cb: # This can be used to alter the headers that will be sent # in the future, for example this is what the MAAS datasource # does. exception_cb(msg=status_msg, exception=url_exc) if timeup(max_wait, start_time): break loop_n = loop_n + 1 LOG.debug("Please wait %s seconds while we wait to try again", sleep_time) time.sleep(sleep_time) return False, None class OauthUrlHelper(object): def __init__(self, consumer_key=None, token_key=None, token_secret=None, consumer_secret=None, skew_data_file="/run/oauth_skew.json"): self.consumer_key = consumer_key self.consumer_secret = consumer_secret or "" self.token_key = token_key self.token_secret = token_secret self.skew_data_file = skew_data_file self._do_oauth = True self.skew_change_limit = 5 required = (self.token_key, self.token_secret, self.consumer_key) if not any(required): self._do_oauth = False elif not all(required): raise ValueError("all or none of token_key, token_secret, or " "consumer_key can be set") old = self.read_skew_file() self.skew_data = old or {} def read_skew_file(self): if self.skew_data_file and os.path.isfile(self.skew_data_file): with open(self.skew_data_file, mode="r") as fp: return json.load(fp) return None def update_skew_file(self, host, value): # this is not atomic if not self.skew_data_file: return cur = self.read_skew_file() if cur is None: cur = {} cur[host] = value with open(self.skew_data_file, mode="w") as fp: fp.write(json.dumps(cur)) def exception_cb(self, msg, exception): if not (isinstance(exception, UrlError) and (exception.code == 403 or exception.code == 401)): return if 'date' not in exception.headers: LOG.warning("Missing header 'date' in %s response", exception.code) return date = exception.headers['date'] try: remote_time = time.mktime(parsedate(date)) except Exception as e: LOG.warning("Failed to convert datetime '%s': %s", date, e) return skew = int(remote_time - time.time()) host = urlparse(exception.url).netloc old_skew = self.skew_data.get(host, 0) if abs(old_skew - skew) > self.skew_change_limit: self.update_skew_file(host, skew) LOG.warning("Setting oauth clockskew for %s to %d", host, skew) self.skew_data[host] = skew return def headers_cb(self, url): if not self._do_oauth: return {} timestamp = None host = urlparse(url).netloc if self.skew_data and host in self.skew_data: timestamp = int(time.time()) + self.skew_data[host] return oauth_headers( url=url, consumer_key=self.consumer_key, token_key=self.token_key, token_secret=self.token_secret, consumer_secret=self.consumer_secret, timestamp=timestamp) def _wrapped(self, wrapped_func, args, kwargs): kwargs['headers_cb'] = partial( self._headers_cb, kwargs.get('headers_cb')) kwargs['exception_cb'] = partial( self._exception_cb, kwargs.get('exception_cb')) return wrapped_func(*args, **kwargs) def wait_for_url(self, *args, **kwargs): return self._wrapped(wait_for_url, args, kwargs) def readurl(self, *args, **kwargs): return self._wrapped(readurl, args, kwargs) def _exception_cb(self, extra_exception_cb, msg, exception): ret = None try: if extra_exception_cb: ret = extra_exception_cb(msg, exception) finally: self.exception_cb(msg, exception) return ret def _headers_cb(self, extra_headers_cb, url): headers = {} if extra_headers_cb: headers = extra_headers_cb(url) headers.update(self.headers_cb(url)) return headers def oauth_headers(url, consumer_key, token_key, token_secret, consumer_secret, timestamp=None): try: import oauthlib.oauth1 as oauth1 except ImportError: raise NotImplementedError('oauth support is not available') if timestamp: timestamp = str(timestamp) else: timestamp = None client = oauth1.Client( consumer_key, client_secret=consumer_secret, resource_owner_key=token_key, resource_owner_secret=token_secret, signature_method=oauth1.SIGNATURE_PLAINTEXT, timestamp=timestamp) _uri, signed_headers, _body = client.sign(url) return signed_headers def retry_on_url_exc(msg, exc): """readurl exception_cb that will retry on NOT_FOUND and Timeout. Returns False to raise the exception from readurl, True to retry. """ if not isinstance(exc, UrlError): return False if exc.code == NOT_FOUND: return True if exc.cause and isinstance(exc.cause, requests.Timeout): return True return False # vi: ts=4 expandtab