1 # Copyright (c) 2018 Cisco and/or its affiliates.
2 # Licensed under the Apache License, Version 2.0 (the "License");
3 # you may not use this file except in compliance with the License.
4 # You may obtain a copy of the License at:
6 # http://www.apache.org/licenses/LICENSE-2.0
8 # Unless required by applicable law or agreed to in writing, software
9 # distributed under the License is distributed on an "AS IS" BASIS,
10 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 # See the License for the specific language governing permissions and
12 # limitations under the License.
14 """Library for SSH connection management."""
17 from time import time, sleep
21 from paramiko import RSAKey
22 from paramiko.ssh_exception import SSHException
23 from scp import SCPClient
24 from robot.api import logger
25 from robot.utils.asserts import assert_equal
27 __all__ = ["exec_cmd", "exec_cmd_no_error"]
32 class SSHTimeout(Exception):
33 """This exception is raised when a timeout occurs."""
38 """Contains methods for managing and using SSH connections."""
40 __MAX_RECV_BUF = 10*1024*1024
41 __existing_connections = {}
49 """Get IP address and port hash from node dictionary.
51 :param node: Node in topology.
53 :returns: IP address and port for the specified node.
57 return hash(frozenset([node['host'], node['port']]))
59 def connect(self, node, attempts=5):
60 """Connect to node prior to running exec_command or scp.
62 If there already is a connection to the node, this method reuses it.
66 node_hash = self._node_hash(node)
67 if node_hash in SSH.__existing_connections:
68 self._ssh = SSH.__existing_connections[node_hash]
69 logger.debug('reusing ssh: {0}'.format(self._ssh))
73 if 'priv_key' in node:
74 pkey = RSAKey.from_private_key(
75 StringIO.StringIO(node['priv_key']))
77 self._ssh = paramiko.SSHClient()
78 self._ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
80 self._ssh.connect(node['host'], username=node['username'],
81 password=node.get('password'), pkey=pkey,
84 self._ssh.get_transport().set_keepalive(10)
86 SSH.__existing_connections[node_hash] = self._ssh
88 logger.trace('connect took {} seconds'.format(time() - start))
89 logger.debug('new ssh: {0}'.format(self._ssh))
91 logger.debug('Connect peer: {0}'.
92 format(self._ssh.get_transport().getpeername()))
93 logger.debug('Connections: {0}'.
94 format(str(SSH.__existing_connections)))
97 self._reconnect(attempts-1)
101 def disconnect(self, node):
102 """Close SSH connection to the node.
104 :param node: The node to disconnect from.
107 node_hash = self._node_hash(node)
108 if node_hash in SSH.__existing_connections:
109 logger.debug('Disconnecting peer: {}, {}'.
110 format(node['host'], node['port']))
111 ssh = SSH.__existing_connections.pop(node_hash)
114 def _reconnect(self, attempts=0):
115 """Close the SSH connection and open it again."""
118 self.disconnect(node)
119 self.connect(node, attempts)
120 logger.debug('Reconnecting peer done: {}'.
121 format(self._ssh.get_transport().getpeername()))
123 def exec_command(self, cmd, timeout=10):
124 """Execute SSH command on a new channel on the connected Node.
126 :param cmd: Command to run on the Node.
127 :param timeout: Maximal time in seconds to wait until the command is
128 done. If set to None then wait forever.
131 :return return_code, stdout, stderr
132 :rtype: tuple(int, str, str)
133 :raise SSHTimeout: If command is not finished in timeout time.
135 stdout = StringIO.StringIO()
136 stderr = StringIO.StringIO()
138 chan = self._ssh.get_transport().open_session(timeout=5)
139 peer = self._ssh.get_transport().getpeername()
140 except AttributeError:
142 chan = self._ssh.get_transport().open_session(timeout=5)
143 peer = self._ssh.get_transport().getpeername()
146 chan = self._ssh.get_transport().open_session(timeout=5)
147 peer = self._ssh.get_transport().getpeername()
148 chan.settimeout(timeout)
150 logger.trace('exec_command on {peer} with timeout {timeout}: {cmd}'
151 .format(peer=peer, timeout=timeout, cmd=cmd))
154 chan.exec_command(cmd)
155 while not chan.exit_status_ready() and timeout is not None:
156 if chan.recv_ready():
157 stdout.write(chan.recv(self.__MAX_RECV_BUF))
159 if chan.recv_stderr_ready():
160 stderr.write(chan.recv_stderr(self.__MAX_RECV_BUF))
162 if time() - start > timeout:
164 'Timeout exception during execution of command: {cmd}\n'
165 'Current contents of stdout buffer: {stdout}\n'
166 'Current contents of stderr buffer: {stderr}\n'
167 .format(cmd=cmd, stdout=stdout.getvalue(),
168 stderr=stderr.getvalue())
172 return_code = chan.recv_exit_status()
174 while chan.recv_ready():
175 stdout.write(chan.recv(self.__MAX_RECV_BUF))
177 while chan.recv_stderr_ready():
178 stderr.write(chan.recv_stderr(self.__MAX_RECV_BUF))
181 logger.trace('exec_command on {peer} took {total} seconds'.
182 format(peer=peer, total=end-start))
184 logger.trace('return RC {rc}'.format(rc=return_code))
185 logger.trace('return STDOUT {stdout}'.format(stdout=stdout.getvalue()))
186 logger.trace('return STDERR {stderr}'.format(stderr=stderr.getvalue()))
187 return return_code, stdout.getvalue(), stderr.getvalue()
189 def exec_command_sudo(self, cmd, cmd_input=None, timeout=30):
190 """Execute SSH command with sudo on a new channel on the connected Node.
192 :param cmd: Command to be executed.
193 :param cmd_input: Input redirected to the command.
194 :param timeout: Timeout.
195 :returns: return_code, stdout, stderr
199 >>> from ssh import SSH
201 >>> ssh.connect(node)
202 >>> # Execute command without input (sudo -S cmd)
203 >>> ssh.exec_command_sudo("ifconfig eth0 down")
204 >>> # Execute command with input (sudo -S cmd <<< "input")
205 >>> ssh.exec_command_sudo("vpp_api_test", "dump_interface_table")
207 if cmd_input is None:
208 command = 'sudo -S {c}'.format(c=cmd)
210 command = 'sudo -S {c} <<< "{i}"'.format(c=cmd, i=cmd_input)
211 return self.exec_command(command, timeout)
213 def exec_command_lxc(self, lxc_cmd, lxc_name, lxc_params='', sudo=True,
215 """Execute command in LXC on a new SSH channel on the connected Node.
217 :param lxc_cmd: Command to be executed.
218 :param lxc_name: LXC name.
219 :param lxc_params: Additional parameters for LXC attach.
220 :param sudo: Run in privileged LXC mode. Default: privileged
221 :param timeout: Timeout.
224 :type lxc_params: str
227 :returns: return_code, stdout, stderr
229 command = "lxc-attach {p} --name {n} -- /bin/sh -c '{c}'"\
230 .format(p=lxc_params, n=lxc_name, c=lxc_cmd)
233 command = 'sudo -S {c}'.format(c=command)
234 return self.exec_command(command, timeout)
236 def interactive_terminal_open(self, time_out=30):
237 """Open interactive terminal on a new channel on the connected Node.
239 :param time_out: Timeout in seconds.
240 :returns: SSH channel with opened terminal.
242 .. warning:: Interruptingcow is used here, and it uses
243 signal(SIGALRM) to let the operating system interrupt program
244 execution. This has the following limitations: Python signal
245 handlers only apply to the main thread, so you cannot use this
246 from other threads. You must not use this in a program that
247 uses SIGALRM itself (this includes certain profilers)
249 chan = self._ssh.get_transport().open_session()
252 chan.settimeout(int(time_out))
253 chan.set_combine_stderr(True)
256 while not buf.endswith((":~$ ", "~]$ ", "~]# ")):
258 chunk = chan.recv(self.__MAX_RECV_BUF)
262 if chan.exit_status_ready():
263 logger.error('Channel exit status ready')
265 except socket.timeout:
266 logger.error('Socket timeout: {0}'.format(buf))
267 raise Exception('Socket timeout: {0}'.format(buf))
270 def interactive_terminal_exec_command(self, chan, cmd, prompt):
271 """Execute command on interactive terminal.
273 interactive_terminal_open() method has to be called first!
275 :param chan: SSH channel with opened terminal.
276 :param cmd: Command to be executed.
277 :param prompt: Command prompt, sequence of characters used to
278 indicate readiness to accept commands.
279 :returns: Command output.
281 .. warning:: Interruptingcow is used here, and it uses
282 signal(SIGALRM) to let the operating system interrupt program
283 execution. This has the following limitations: Python signal
284 handlers only apply to the main thread, so you cannot use this
285 from other threads. You must not use this in a program that
286 uses SIGALRM itself (this includes certain profilers)
288 chan.sendall('{c}\n'.format(c=cmd))
290 while not buf.endswith(prompt):
292 chunk = chan.recv(self.__MAX_RECV_BUF)
296 if chan.exit_status_ready():
297 logger.error('Channel exit status ready')
299 except socket.timeout:
300 logger.error('Socket timeout during execution of command: '
301 '{0}\nBuffer content:\n{1}'.format(cmd, buf))
302 raise Exception('Socket timeout during execution of command: '
303 '{0}\nBuffer content:\n{1}'.format(cmd, buf))
304 tmp = buf.replace(cmd.replace('\n', ''), '')
306 tmp.replace(item, '')
310 def interactive_terminal_close(chan):
311 """Close interactive terminal SSH channel.
313 :param: chan: SSH channel to be closed.
317 def scp(self, local_path, remote_path, get=False, timeout=10):
318 """Copy files from local_path to remote_path or vice versa.
320 connect() method has to be called first!
322 :param local_path: Path to local file that should be uploaded; or
323 path where to save remote file.
324 :param remote_path: Remote path where to place uploaded file; or
325 path to remote file which should be downloaded.
326 :param get: scp operation to perform. Default is put.
327 :param timeout: Timeout value in seconds.
328 :type local_path: str
329 :type remote_path: str
334 logger.trace('SCP {0} to {1}:{2}'.format(
335 local_path, self._ssh.get_transport().getpeername(),
338 logger.trace('SCP {0}:{1} to {2}'.format(
339 self._ssh.get_transport().getpeername(), remote_path,
341 # SCPCLient takes a paramiko transport as its only argument
342 scp = SCPClient(self._ssh.get_transport(), socket_timeout=timeout)
345 scp.put(local_path, remote_path)
347 scp.get(remote_path, local_path)
350 logger.trace('SCP took {0} seconds'.format(end-start))
353 def exec_cmd(node, cmd, timeout=600, sudo=False):
354 """Convenience function to ssh/exec/return rc, out & err.
356 Returns (rc, stdout, stderr).
359 raise TypeError('Node parameter is None')
361 raise TypeError('Command parameter is None')
363 raise ValueError('Empty command parameter')
368 except SSHException as err:
369 logger.error("Failed to connect to node" + str(err))
370 return None, None, None
374 (ret_code, stdout, stderr) = ssh.exec_command(cmd, timeout=timeout)
376 (ret_code, stdout, stderr) = ssh.exec_command_sudo(cmd,
378 except SSHException as err:
380 return None, None, None
382 return ret_code, stdout, stderr
385 def exec_cmd_no_error(node, cmd, timeout=600, sudo=False):
386 """Convenience function to ssh/exec/return out & err.
388 Verifies that return code is zero.
390 Returns (stdout, stderr).
392 (ret_code, stdout, stderr) = exec_cmd(node, cmd, timeout=timeout, sudo=sudo)
393 assert_equal(ret_code, 0, 'Command execution failed: "{}"\n{}'.
395 return stdout, stderr