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# Copyright (c) 2015 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
__all__ = ["exec_cmd"]
# TODO: Attempt to recycle SSH connections
# 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).
"""
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 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):
"""Convenience function to ssh/exec/return rc & out.
Returns (rc, stdout).
"""
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:
(ret_code, stdout, stderr) = ssh.exec_command(cmd, timeout=timeout)
except Exception, e:
logger.error(e)
return None
return (ret_code, stdout, stderr)
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