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# Copyright 2012 OpenStack Foundation
# All Rights Reserved.
#
# 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 select
import socket
import time
import warnings
from oslo_log import log as logging
import six
from tempest_lib import exceptions
with warnings.catch_warnings():
warnings.simplefilter("ignore")
import paramiko
LOG = logging.getLogger(__name__)
class Client(object):
def __init__(self, host, username, password=None, timeout=300, pkey=None,
channel_timeout=10, look_for_keys=False, key_filename=None):
self.host = host
self.username = username
self.password = password
if isinstance(pkey, six.string_types):
pkey = paramiko.RSAKey.from_private_key(
six.StringIO(str(pkey)))
self.pkey = pkey
self.look_for_keys = look_for_keys
self.key_filename = key_filename
self.timeout = int(timeout)
self.channel_timeout = float(channel_timeout)
self.buf_size = 1024
def _get_ssh_connection(self, sleep=1.5, backoff=1):
"""Returns an ssh connection to the specified host."""
bsleep = sleep
ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(
paramiko.AutoAddPolicy())
_start_time = time.time()
if self.pkey is not None:
LOG.info("Creating ssh connection to '%s' as '%s'"
" with public key authentication",
self.host, self.username)
else:
LOG.info("Creating ssh connection to '%s' as '%s'"
" with password %s",
self.host, self.username, str(self.password))
attempts = 0
while True:
try:
ssh.connect(self.host, username=self.username,
password=self.password,
look_for_keys=self.look_for_keys,
key_filename=self.key_filename,
timeout=self.channel_timeout, pkey=self.pkey)
LOG.info("ssh connection to %s@%s successfuly created",
self.username, self.host)
return ssh
except (EOFError,
socket.error,
paramiko.SSHException) as e:
if self._is_timed_out(_start_time):
LOG.exception("Failed to establish authenticated ssh"
" connection to %s@%s after %d attempts",
self.username, self.host, attempts)
raise exceptions.SSHTimeout(host=self.host,
user=self.username,
password=self.password)
bsleep += backoff
attempts += 1
LOG.warning("Failed to establish authenticated ssh"
" connection to %s@%s (%s). Number attempts: %s."
" Retry after %d seconds.",
self.username, self.host, e, attempts, bsleep)
time.sleep(bsleep)
def _is_timed_out(self, start_time):
return (time.time() - self.timeout) > start_time
@staticmethod
def _can_system_poll():
return hasattr(select, 'poll')
def exec_command(self, cmd, encoding="utf-8"):
"""Execute the specified command on the server
Note that this method is reading whole command outputs to memory, thus
shouldn't be used for large outputs.
:param str cmd: Command to run at remote server.
:param str encoding: Encoding for result from paramiko.
Result will not be decoded if None.
:returns: data read from standard output of the command.
:raises: SSHExecCommandFailed if command returns nonzero
status. The exception contains command status stderr content.
:raises: TimeoutException if cmd doesn't end when timeout expires.
"""
ssh = self._get_ssh_connection()
transport = ssh.get_transport()
channel = transport.open_session()
channel.fileno() # Register event pipe
channel.exec_command(cmd)
channel.shutdown_write()
exit_status = channel.recv_exit_status()
# If the executing host is linux-based, poll the channel
if self._can_system_poll():
out_data_chunks = []
err_data_chunks = []
poll = select.poll()
poll.register(channel, select.POLLIN)
start_time = time.time()
while True:
ready = poll.poll(self.channel_timeout)
if not any(ready):
if not self._is_timed_out(start_time):
continue
raise exceptions.TimeoutException(
"Command: '{0}' executed on host '{1}'.".format(
cmd, self.host))
if not ready[0]: # If there is nothing to read.
continue
out_chunk = err_chunk = None
if channel.recv_ready():
out_chunk = channel.recv(self.buf_size)
out_data_chunks += out_chunk,
if channel.recv_stderr_ready():
err_chunk = channel.recv_stderr(self.buf_size)
err_data_chunks += err_chunk,
if channel.closed and not err_chunk and not out_chunk:
break
out_data = b''.join(out_data_chunks)
err_data = b''.join(err_data_chunks)
# Just read from the channels
else:
out_file = channel.makefile('rb', self.buf_size)
err_file = channel.makefile_stderr('rb', self.buf_size)
out_data = out_file.read()
err_data = err_file.read()
if encoding:
out_data = out_data.decode(encoding)
err_data = err_data.decode(encoding)
if 0 != exit_status:
raise exceptions.SSHExecCommandFailed(
command=cmd, exit_status=exit_status,
stderr=err_data, stdout=out_data)
return out_data
def test_connection_auth(self):
"""Raises an exception when we can not connect to server via ssh."""
connection = self._get_ssh_connection()
connection.close()
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