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# Copyright 2016 The Kubernetes Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import json
import pydoc
import sys
from kubernetes import client
PYDOC_RETURN_LABEL = ":return:"
PYDOC_FOLLOW_PARAM = ":param bool follow:"
# Removing this suffix from return type name should give us event's object
# type. e.g., if list_namespaces() returns "NamespaceList" type,
# then list_namespaces(watch=true) returns a stream of events with objects
# of type "Namespace". In case this assumption is not true, user should
# provide return_type to Watch class's __init__.
TYPE_LIST_SUFFIX = "List"
PY2 = sys.version_info[0] == 2
if PY2:
import httplib
HTTP_STATUS_GONE = httplib.GONE
else:
import http
HTTP_STATUS_GONE = http.HTTPStatus.GONE
class SimpleNamespace:
def __init__(self, **kwargs):
self.__dict__.update(kwargs)
def _find_return_type(func):
for line in pydoc.getdoc(func).splitlines():
if line.startswith(PYDOC_RETURN_LABEL):
return line[len(PYDOC_RETURN_LABEL):].strip()
return ""
def iter_resp_lines(resp):
buffer = bytearray()
for segment in resp.stream(amt=None, decode_content=False):
# Append the segment (chunk) to the buffer
#
# Performance note: depending on contents of buffer and the type+value of segment,
# encoding segment into the buffer could be a wasteful step. The approach used here
# simplifies the logic farther down, but in the future it may be reasonable to
# sacrifice readability for performance.
if isinstance(segment, bytes):
buffer.extend(segment)
elif isinstance(segment, str):
buffer.extend(segment.encode("utf-8"))
else:
raise TypeError(
f"Received invalid segment type, {type(segment)}, from stream. Accepts only 'str' or 'bytes'.")
# Split by newline (safe for utf-8 because multi-byte sequences cannot contain the newline byte)
next_newline = buffer.find(b'\n')
while next_newline != -1:
# Convert bytes to a valid utf-8 string, replacing any invalid utf-8 with the '�' character
line = buffer[:next_newline].decode(
"utf-8", errors="replace")
buffer = buffer[next_newline+1:]
if line:
yield line
next_newline = buffer.find(b'\n')
class Watch(object):
def __init__(self, return_type=None):
self._raw_return_type = return_type
self._stop = False
self._api_client = client.ApiClient()
self.resource_version = None
def stop(self):
self._stop = True
def get_return_type(self, func):
if self._raw_return_type:
return self._raw_return_type
return_type = _find_return_type(func)
if return_type.endswith(TYPE_LIST_SUFFIX):
return return_type[:-len(TYPE_LIST_SUFFIX)]
return return_type
def get_watch_argument_name(self, func):
if PYDOC_FOLLOW_PARAM in pydoc.getdoc(func):
return 'follow'
else:
return 'watch'
def unmarshal_event(self, data, return_type):
js = json.loads(data)
js['raw_object'] = js['object']
# BOOKMARK event is treated the same as ERROR for a quick fix of
# decoding exception
# TODO: make use of the resource_version in BOOKMARK event for more
# efficient WATCH
if return_type and js['type'] != 'ERROR' and js['type'] != 'BOOKMARK':
obj = SimpleNamespace(data=json.dumps(js['raw_object']))
js['object'] = self._api_client.deserialize(obj, return_type)
if hasattr(js['object'], 'metadata'):
self.resource_version = js['object'].metadata.resource_version
# For custom objects that we don't have model defined, json
# deserialization results in dictionary
elif (isinstance(js['object'], dict) and 'metadata' in js['object']
and 'resourceVersion' in js['object']['metadata']):
self.resource_version = js['object']['metadata'][
'resourceVersion']
return js
def stream(self, func, *args, **kwargs):
"""Watch an API resource and stream the result back via a generator.
Note that watching an API resource can expire. The method tries to
resume automatically once from the last result, but if that last result
is too old as well, an `ApiException` exception will be thrown with
``code`` 410. In that case you have to recover yourself, probably
by listing the API resource to obtain the latest state and then
watching from that state on by setting ``resource_version`` to
one returned from listing.
:param func: The API function pointer. Any parameter to the function
can be passed after this parameter.
:return: Event object with these keys:
'type': The type of event such as "ADDED", "DELETED", etc.
'raw_object': a dict representing the watched object.
'object': A model representation of raw_object. The name of
model will be determined based on
the func's doc string. If it cannot be determined,
'object' value will be the same as 'raw_object'.
Example:
v1 = kubernetes.client.CoreV1Api()
watch = kubernetes.watch.Watch()
for e in watch.stream(v1.list_namespace, resource_version=1127):
type = e['type']
object = e['object'] # object is one of type return_type
raw_object = e['raw_object'] # raw_object is a dict
...
if should_stop:
watch.stop()
"""
self._stop = False
return_type = self.get_return_type(func)
watch_arg = self.get_watch_argument_name(func)
kwargs[watch_arg] = True
kwargs['_preload_content'] = False
if 'resource_version' in kwargs:
self.resource_version = kwargs['resource_version']
# Do not attempt retries if user specifies a timeout.
# We want to ensure we are returning within that timeout.
disable_retries = ('timeout_seconds' in kwargs)
retry_after_410 = False
while True:
resp = func(*args, **kwargs)
try:
for line in iter_resp_lines(resp):
# unmarshal when we are receiving events from watch,
# return raw string when we are streaming log
if watch_arg == "watch":
event = self.unmarshal_event(line, return_type)
if isinstance(event, dict) \
and event['type'] == 'ERROR':
obj = event['raw_object']
# Current request expired, let's retry, (if enabled)
# but only if we have not already retried.
if not disable_retries and not retry_after_410 and \
obj['code'] == HTTP_STATUS_GONE:
retry_after_410 = True
break
else:
reason = "%s: %s" % (
obj['reason'], obj['message'])
raise client.rest.ApiException(
status=obj['code'], reason=reason)
else:
retry_after_410 = False
yield event
else:
yield line
if self._stop:
break
finally:
resp.close()
resp.release_conn()
if self.resource_version is not None:
kwargs['resource_version'] = self.resource_version
else:
self._stop = True
if self._stop or disable_retries:
break
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