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# Copyright (c) 2016 Cisco and/or its affiliates.
# 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 paramiko
from scp import SCPClient
from time import time
from robot.api import logger
from interruptingcow import timeout
from robot.utils.asserts import assert_equal, assert_not_equal
__all__ = ["exec_cmd", "exec_cmd_no_error"]
# TODO: load priv key
class SSH(object):
__MAX_RECV_BUF = 10*1024*1024
__existing_connections = {}
def __init__(self):
self._ssh = paramiko.SSHClient()
self._ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
self._hostname = None
def _node_hash(self, node):
return hash(frozenset([node['host'], node['port']]))
def connect(self, node):
"""Connect to node prior to running exec_command or scp.
If there already is a connection to the node, this method reuses it.
"""
self._hostname = node['host']
node_hash = self._node_hash(node)
if node_hash in self.__existing_connections:
self._ssh = self.__existing_connections[node_hash]
else:
start = time()
self._ssh.connect(node['host'], username=node['username'],
password=node['password'])
self.__existing_connections[node_hash] = self._ssh
logger.trace('connect took {} seconds'.format(time() - start))
def exec_command(self, cmd, timeout=10):
"""Execute SSH command on a new channel on the connected Node.
Returns (return_code, stdout, stderr).
"""
logger.trace('exec_command on {0}: {1}'.format(self._hostname, cmd))
start = time()
chan = self._ssh.get_transport().open_session()
if timeout is not None:
chan.settimeout(int(timeout))
chan.exec_command(cmd)
end = time()
logger.trace('exec_command "{0}" on {1} took {2} seconds'.format(
cmd, self._hostname, end-start))
stdout = ""
while True:
buf = chan.recv(self.__MAX_RECV_BUF)
stdout += buf
if not buf:
break
stderr = ""
while True:
buf = chan.recv_stderr(self.__MAX_RECV_BUF)
stderr += buf
if not buf:
break
return_code = chan.recv_exit_status()
logger.trace('chan_recv/_stderr took {} seconds'.format(time()-end))
return (return_code, stdout, stderr)
def exec_command_sudo(self, cmd, cmd_input=None, timeout=10):
"""Execute SSH command with sudo on a new channel on the connected Node.
:param cmd: Command to be executed.
:param cmd_input: Input redirected to the command.
:param timeout: Timeout.
:return: return_code, stdout, stderr
:Example:
>>> from ssh import SSH
>>> ssh = SSH()
>>> ssh.connect(node)
>>> #Execute command without input (sudo -S cmd)
>>> ssh.exex_command_sudo("ifconfig eth0 down")
>>> #Execute command with input (sudo -S cmd <<< "input")
>>> ssh.exex_command_sudo("vpe_api_test", "dump_interface_table")
"""
if cmd_input is None:
command = 'sudo -S {c}'.format(c=cmd)
else:
command = 'sudo -S {c} <<< "{i}"'.format(c=cmd, i=cmd_input)
return self.exec_command(command, timeout)
def interactive_terminal_open(self, time_out=10):
"""Open interactive terminal on a new channel on the connected Node.
:param time_out: Timeout in seconds.
:return: SSH channel with opened terminal.
.. warning:: Interruptingcow is used here, and it uses
signal(SIGALRM) to let the operating system interrupt program
execution. This has the following limitations: Python signal
handlers only apply to the main thread, so you cannot use this
from other threads. You must not use this in a program that
uses SIGALRM itself (this includes certain profilers)
"""
chan = self._ssh.get_transport().open_session()
chan.get_pty()
chan.invoke_shell()
chan.settimeout(int(time_out))
buf = ''
try:
with timeout(time_out, exception=RuntimeError):
while not buf.endswith(':~$ '):
if chan.recv_ready():
buf = chan.recv(4096)
except RuntimeError:
raise Exception('Open interactive terminal timeout.')
return chan
def interactive_terminal_exec_command(self, chan, cmd, prompt,
time_out=10):
"""Execute command on interactive terminal.
interactive_terminal_open() method has to be called first!
:param chan: SSH channel with opened terminal.
:param cmd: Command to be executed.
:param prompt: Command prompt, sequence of characters used to
indicate readiness to accept commands.
:param time_out: Timeout in seconds.
:return: Command output.
.. warning:: Interruptingcow is used here, and it uses
signal(SIGALRM) to let the operating system interrupt program
execution. This has the following limitations: Python signal
handlers only apply to the main thread, so you cannot use this
from other threads. You must not use this in a program that
uses SIGALRM itself (this includes certain profilers)
"""
chan.sendall('{c}\n'.format(c=cmd))
buf = ''
try:
with timeout(time_out, exception=RuntimeError):
while not buf.endswith(prompt):
if chan.recv_ready():
buf += chan.recv(4096)
except RuntimeError:
raise Exception("Exec '{c}' timeout.".format(c=cmd))
tmp = buf.replace(cmd.replace('\n', ''), '')
return tmp.replace(prompt, '')
def interactive_terminal_close(self, chan):
"""Close interactive terminal SSH channel.
:param: chan: SSH channel to be closed.
"""
chan.close()
def scp(self, local_path, remote_path):
"""Copy files from local_path to remote_path.
connect() method has to be called first!
"""
logger.trace('SCP {0} to {1}:{2}'.format(
local_path, self._hostname, remote_path))
# SCPCLient takes a paramiko transport as its only argument
scp = SCPClient(self._ssh.get_transport())
start = time()
scp.put(local_path, remote_path)
scp.close()
end = time()
logger.trace('SCP took {0} seconds'.format(end-start))
def exec_cmd(node, cmd, timeout=None, sudo=False):
"""Convenience function to ssh/exec/return rc, out & err.
Returns (rc, stdout, stderr).
"""
if node is None:
raise TypeError('Node parameter is None')
if cmd is None:
raise TypeError('Command parameter is None')
if len(cmd) == 0:
raise ValueError('Empty command parameter')
ssh = SSH()
try:
ssh.connect(node)
except Exception, e:
logger.error("Failed to connect to node" + e)
return None
try:
if not sudo:
(ret_code, stdout, stderr) = ssh.exec_command(cmd, timeout=timeout)
else:
(ret_code, stdout, stderr) = ssh.exec_command_sudo(cmd,
timeout=timeout)
except Exception, e:
logger.error(e)
return None
return (ret_code, stdout, stderr)
def exec_cmd_no_error(node, cmd, timeout=None, sudo=False):
"""Convenience function to ssh/exec/return out & err.
Verifies that return code is zero.
Returns (stdout, stderr).
"""
(rc, stdout, stderr) = exec_cmd(node,cmd, timeout=timeout, sudo=sudo)
assert_equal(rc, 0, 'Command execution failed: "{}"\n{}'.
format(cmd, stderr))
return (stdout, stderr)
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