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# 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 threading
import time
from concurrent.futures import ThreadPoolExecutor, TimeoutError, as_completed
from email.utils import parsedate
from errno import ENOENT
from functools import partial
from http.client import NOT_FOUND
from itertools import count
from typing import Any, Callable, Iterator, List, Optional, Tuple, Union
from urllib.parse import quote, urlparse, urlunparse
import requests
from requests import exceptions
from cloudinit import log as logging
from cloudinit import version
LOG = logging.getLogger(__name__)
REDACTED = "REDACTED"
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 += quote(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) -> Union["FileResponse", "UrlResponse"]:
"""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) from e
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:
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:
def __init__(self, response: requests.Response):
self._response = response
@property
def contents(self) -> bytes:
if self._response.content is None:
return b""
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
def iter_content(
self, chunk_size: Optional[int] = 1, decode_unicode: bool = False
) -> Iterator[bytes]:
"""Iterates over the response data.
When stream=True is set on the request, this avoids reading the content
at once into memory for large responses.
:param chunk_size: Number of bytes it should read into memory.
:param decode_unicode: If True, content will be decoded using the best
available encoding based on the response.
"""
yield from self._response.iter_content(chunk_size, decode_unicode)
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 "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="",
stream: bool = False,
) -> UrlResponse:
"""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. May be a tuple
if specifying (connection timeout, read timeout).
: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.
:param stream: if False, the response content will be immediately
downloaded.
"""
url = _cleanurl(url)
req_args = {
"url": url,
"stream": stream,
}
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:
if isinstance(timeout, tuple):
req_args["timeout"] = timeout
else:
req_args["timeout"] = max(float(timeout), 0)
if headers_redact is None:
headers_redact = []
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 hasattr( # This appeared in v 0.10.8
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 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)
raise excps[-1]
def _run_func_with_delay(
func: Callable[..., Any],
addr: str,
timeout: int,
event: threading.Event,
delay: Optional[float] = None,
) -> Any:
"""Execute func with optional delay"""
if delay:
# event returns True iff the flag is set to true: indicating that
# another thread has already completed successfully, no need to try
# again - exit early
if event.wait(timeout=delay):
return
return func(addr, timeout)
def dual_stack(
func: Callable[..., Any],
addresses: List[str],
stagger_delay: float = 0.150,
timeout: int = 10,
) -> Tuple:
"""execute multiple callbacks in parallel
Run blocking func against two different addresses staggered with a
delay. The first call to return successfully is returned from this
function and remaining unfinished calls are cancelled if they have not
yet started
"""
return_result = None
returned_address = None
last_exception = None
exceptions = []
is_done = threading.Event()
# future work: add cancel_futures to Python stdlib ThreadPoolExecutor
# context manager implementation
#
# for now we don't use this feature since it only supports python >3.8
# and doesn't provide a context manager and only marginal benefit
executor = ThreadPoolExecutor(max_workers=len(addresses))
try:
futures = {
executor.submit(
_run_func_with_delay,
func=func,
addr=addr,
timeout=timeout,
event=is_done,
delay=(i * stagger_delay),
): addr
for i, addr in enumerate(addresses)
}
# handle returned requests in order of completion
for future in as_completed(futures, timeout=timeout):
returned_address = futures[future]
return_exception = future.exception()
if return_exception:
last_exception = return_exception
exceptions.append(last_exception)
else:
return_result = future.result()
if return_result:
# communicate to other threads that they do not need to
# try: this thread has already succeeded
is_done.set()
return (returned_address, return_result)
# No success, return the last exception but log them all for
# debugging
if last_exception:
LOG.warning(
"Exception(s) %s during request to "
"%s, raising last exception",
exceptions,
returned_address,
)
raise last_exception
else:
LOG.error("Empty result for address %s", returned_address)
raise ValueError("No result returned")
# when max_wait expires, log but don't throw (retries happen)
except TimeoutError:
LOG.warning(
"Timed out waiting for addresses: %s, "
"exception(s) raised while waiting: %s",
" ".join(addresses),
" ".join(exceptions), # type: ignore
)
finally:
executor.shutdown(wait=False)
return (returned_address, return_result)
def wait_for_url(
urls,
max_wait=None,
timeout=None,
status_cb: Callable = LOG.debug, # some sources use different log levels
headers_cb: Optional[Callable] = None,
headers_redact=None,
sleep_time: int = 1,
exception_cb: Optional[Callable] = None,
sleep_time_cb: Optional[Callable[[Any, int], int]] = None,
request_method: str = "",
connect_synchronously: bool = True,
async_delay: float = 0.150,
):
"""
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
connect_synchronously: if false, enables executing requests in parallel
async_delay: delay before parallel metadata requests, see RFC 6555
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.
"""
def default_sleep_time(_, loop_number: int) -> int:
return int(loop_number / 5) + 1
def timeup(max_wait, start_time):
"""Check if time is up based on start time and max wait"""
if max_wait is None:
return False
return (max_wait <= 0) or (time.time() - start_time > max_wait)
def handle_url_response(response, url):
"""Map requests response code/contents to internal "UrlError" type"""
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:
reason = ""
url_exc = None
return (url_exc, reason)
def read_url_handle_exceptions(
url_reader_cb, urls, start_time, exc_cb, log_cb
):
"""Execute request, handle response, optionally log exception"""
reason = ""
url = None
try:
url, response = url_reader_cb(urls)
url_exc, reason = handle_url_response(response, url)
if not url_exc:
return (url, response)
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,
)
log_cb(status_msg)
if exc_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.
exc_cb(msg=status_msg, exception=url_exc)
def read_url_cb(url, timeout):
return readurl(
url,
headers={} if headers_cb is None else headers_cb(url),
headers_redact=headers_redact,
timeout=timeout,
check_status=False,
request_method=request_method,
)
def read_url_serial(start_time, timeout, exc_cb, log_cb):
"""iterate over list of urls, request each one and handle responses
and thrown exceptions individually per url
"""
def url_reader_serial(url):
return (url, read_url_cb(url, timeout))
for url in urls:
now = time.time()
if loop_n != 0:
if timeup(max_wait, start_time):
return
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)
out = read_url_handle_exceptions(
url_reader_serial, url, start_time, exc_cb, log_cb
)
if out:
return out
def read_url_parallel(start_time, timeout, exc_cb, log_cb):
"""pass list of urls to dual_stack which sends requests in parallel
handle response and exceptions of the first endpoint to respond
"""
url_reader_parallel = partial(
dual_stack,
read_url_cb,
stagger_delay=async_delay,
timeout=timeout,
)
out = read_url_handle_exceptions(
url_reader_parallel, urls, start_time, exc_cb, log_cb
)
if out:
return out
start_time = time.time()
# Dual-stack support factored out serial and parallel execution paths to
# allow the retry loop logic to exist separately from the http calls.
# Serial execution should be fundamentally the same as before, but with a
# layer of indirection so that the parallel dual-stack path may use the
# same max timeout logic.
do_read_url = (
read_url_serial if connect_synchronously else read_url_parallel
)
calculate_sleep_time = sleep_time_cb or default_sleep_time
loop_n: int = 0
response = None
while True:
sleep_time = calculate_sleep_time(response, loop_n)
url = do_read_url(start_time, timeout, exception_cb, status_cb)
if url:
address, response = url
return (address, response.contents)
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)
# shorten timeout to not run way over max_time
# timeout=0.0 causes exceptions in urllib, set to None if zero
timeout = int((start_time + max_wait) - time.time()) or None
LOG.error("Timed out, no response from urls: %s", urls)
return False, None
class OauthUrlHelper:
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 as e:
raise NotImplementedError("oauth support is not available") from e
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, *, retry_codes=(NOT_FOUND,), retry_instances=(requests.Timeout,)
):
"""Configurable retry exception callback for readurl().
:param retry_codes: Codes to retry on. Defaults to 404.
:param retry_instances: Exception types to retry on. Defaults to
requests.Timeout.
:returns: False to raise the exception from readurl(), True to retry.
"""
if not isinstance(exc, UrlError):
return False
if exc.code in retry_codes:
return True
if exc.cause and isinstance(exc.cause, retry_instances):
return True
return False
# vi: ts=4 expandtab
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