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ws_client.py
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ws_client.py
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# Copyright 2018 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.
from kubernetes.client.rest import ApiException
import certifi
import collections
import select
import ssl
import time
import six
import yaml
from six.moves.urllib.parse import urlencode, quote_plus, urlparse, urlunparse
from websocket import WebSocket, ABNF, enableTrace
STDIN_CHANNEL = 0
STDOUT_CHANNEL = 1
STDERR_CHANNEL = 2
ERROR_CHANNEL = 3
RESIZE_CHANNEL = 4
class WSClient:
def __init__(self, configuration, url, headers):
"""A websocket client with support for channels.
Exec command uses different channels for different streams. for
example, 0 is stdin, 1 is stdout and 2 is stderr. Some other API calls
like port forwarding can forward different pods' streams to different
channels.
"""
enableTrace(False)
header = []
self._connected = False
self._channels = {}
self._all = ""
# We just need to pass the Authorization, ignore all the other
# http headers we get from the generated code
if headers and 'authorization' in headers:
header.append("authorization: %s" % headers['authorization'])
if headers and 'sec-websocket-protocol' in headers:
header.append("sec-websocket-protocol: %s" %
headers['sec-websocket-protocol'])
else:
header.append("sec-websocket-protocol: v4.channel.k8s.io")
if url.startswith('wss://') and configuration.verify_ssl:
ssl_opts = {
'cert_reqs': ssl.CERT_REQUIRED,
'ca_certs': configuration.ssl_ca_cert or certifi.where(),
}
if configuration.assert_hostname is not None:
ssl_opts['check_hostname'] = configuration.assert_hostname
else:
ssl_opts = {'cert_reqs': ssl.CERT_NONE}
if configuration.cert_file:
ssl_opts['certfile'] = configuration.cert_file
if configuration.key_file:
ssl_opts['keyfile'] = configuration.key_file
self.sock = WebSocket(sslopt=ssl_opts, skip_utf8_validation=False)
if configuration.proxy:
proxy_url = urlparse(configuration.proxy)
self.sock.connect(url, header=header, http_proxy_host=proxy_url.hostname, http_proxy_port=proxy_url.port)
else:
self.sock.connect(url, header=header)
self._connected = True
def peek_channel(self, channel, timeout=0):
"""Peek a channel and return part of the input,
empty string otherwise."""
self.update(timeout=timeout)
if channel in self._channels:
return self._channels[channel]
return ""
def read_channel(self, channel, timeout=0):
"""Read data from a channel."""
if channel not in self._channels:
ret = self.peek_channel(channel, timeout)
else:
ret = self._channels[channel]
if channel in self._channels:
del self._channels[channel]
return ret
def readline_channel(self, channel, timeout=None):
"""Read a line from a channel."""
if timeout is None:
timeout = float("inf")
start = time.time()
while self.is_open() and time.time() - start < timeout:
if channel in self._channels:
data = self._channels[channel]
if "\n" in data:
index = data.find("\n")
ret = data[:index]
data = data[index+1:]
if data:
self._channels[channel] = data
else:
del self._channels[channel]
return ret
self.update(timeout=(timeout - time.time() + start))
def write_channel(self, channel, data):
"""Write data to a channel."""
self.sock.send(chr(channel) + data)
def peek_stdout(self, timeout=0):
"""Same as peek_channel with channel=1."""
return self.peek_channel(STDOUT_CHANNEL, timeout=timeout)
def read_stdout(self, timeout=None):
"""Same as read_channel with channel=1."""
return self.read_channel(STDOUT_CHANNEL, timeout=timeout)
def readline_stdout(self, timeout=None):
"""Same as readline_channel with channel=1."""
return self.readline_channel(STDOUT_CHANNEL, timeout=timeout)
def peek_stderr(self, timeout=0):
"""Same as peek_channel with channel=2."""
return self.peek_channel(STDERR_CHANNEL, timeout=timeout)
def read_stderr(self, timeout=None):
"""Same as read_channel with channel=2."""
return self.read_channel(STDERR_CHANNEL, timeout=timeout)
def readline_stderr(self, timeout=None):
"""Same as readline_channel with channel=2."""
return self.readline_channel(STDERR_CHANNEL, timeout=timeout)
def read_all(self):
"""Return buffered data received on stdout and stderr channels.
This is useful for non-interactive call where a set of command passed
to the API call and their result is needed after the call is concluded.
Should be called after run_forever() or update()
TODO: Maybe we can process this and return a more meaningful map with
channels mapped for each input.
"""
out = self._all
self._all = ""
self._channels = {}
return out
def is_open(self):
"""True if the connection is still alive."""
return self._connected
def write_stdin(self, data):
"""The same as write_channel with channel=0."""
self.write_channel(STDIN_CHANNEL, data)
def update(self, timeout=0):
"""Update channel buffers with at most one complete frame of input."""
if not self.is_open():
return
if not self.sock.connected:
self._connected = False
return
r, _, _ = select.select(
(self.sock.sock, ), (), (), timeout)
if r:
op_code, frame = self.sock.recv_data_frame(True)
if op_code == ABNF.OPCODE_CLOSE:
self._connected = False
return
elif op_code == ABNF.OPCODE_BINARY or op_code == ABNF.OPCODE_TEXT:
data = frame.data
if six.PY3:
data = data.decode("utf-8", "replace")
if len(data) > 1:
channel = ord(data[0])
data = data[1:]
if data:
if channel in [STDOUT_CHANNEL, STDERR_CHANNEL]:
# keeping all messages in the order they received
# for non-blocking call.
self._all += data
if channel not in self._channels:
self._channels[channel] = data
else:
self._channels[channel] += data
def run_forever(self, timeout=None):
"""Wait till connection is closed or timeout reached. Buffer any input
received during this time."""
if timeout:
start = time.time()
while self.is_open() and time.time() - start < timeout:
self.update(timeout=(timeout - time.time() + start))
else:
while self.is_open():
self.update(timeout=None)
@property
def returncode(self):
"""
The return code, A None value indicates that the process hasn't
terminated yet.
"""
if self.is_open():
return None
else:
err = self.read_channel(ERROR_CHANNEL)
err = yaml.safe_load(err)
if err['status'] == "Success":
return 0
return int(err['details']['causes'][0]['message'])
def close(self, **kwargs):
"""
close websocket connection.
"""
self._connected = False
if self.sock:
self.sock.close(**kwargs)
WSResponse = collections.namedtuple('WSResponse', ['data'])
def get_websocket_url(url):
parsed_url = urlparse(url)
parts = list(parsed_url)
if parsed_url.scheme == 'http':
parts[0] = 'ws'
elif parsed_url.scheme == 'https':
parts[0] = 'wss'
return urlunparse(parts)
def websocket_call(configuration, *args, **kwargs):
"""An internal function to be called in api-client when a websocket
connection is required. args and kwargs are the parameters of
apiClient.request method."""
url = args[1]
_request_timeout = kwargs.get("_request_timeout", 60)
_preload_content = kwargs.get("_preload_content", True)
headers = kwargs.get("headers")
# Expand command parameter list to indivitual command params
query_params = []
for key, value in kwargs.get("query_params", {}):
if key == 'command' and isinstance(value, list):
for command in value:
query_params.append((key, command))
else:
query_params.append((key, value))
if query_params:
url += '?' + urlencode(query_params)
try:
client = WSClient(configuration, get_websocket_url(url), headers)
if not _preload_content:
return client
client.run_forever(timeout=_request_timeout)
return WSResponse('%s' % ''.join(client.read_all()))
except (Exception, KeyboardInterrupt, SystemExit) as e:
raise ApiException(status=0, reason=str(e))