1 # Copyright (c) 2016 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 :return: IP address and port for the specified node.
57 return hash(frozenset([node['host'], node['port']]))
59 def connect(self, node):
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.
65 node_hash = self._node_hash(node)
66 if node_hash in SSH.__existing_connections:
67 self._ssh = SSH.__existing_connections[node_hash]
68 logger.debug('reusing ssh: {0}'.format(self._ssh))
72 if 'priv_key' in node:
73 pkey = RSAKey.from_private_key(
74 StringIO.StringIO(node['priv_key']))
76 self._ssh = paramiko.SSHClient()
77 self._ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
79 self._ssh.connect(node['host'], username=node['username'],
80 password=node.get('password'), pkey=pkey,
83 self._ssh.get_transport().set_keepalive(10)
85 SSH.__existing_connections[node_hash] = self._ssh
87 logger.trace('connect took {} seconds'.format(time() - start))
88 logger.debug('new ssh: {0}'.format(self._ssh))
90 logger.debug('Connect peer: {0}'.
91 format(self._ssh.get_transport().getpeername()))
92 logger.debug('Connections: {0}'.format(str(SSH.__existing_connections)))
94 def disconnect(self, node):
95 """Close SSH connection to the node.
97 :param node: The node to disconnect from.
100 node_hash = self._node_hash(node)
101 if node_hash in SSH.__existing_connections:
102 logger.debug('Disconnecting peer: {}, {}'.
103 format(node['host'], node['port']))
104 ssh = SSH.__existing_connections.pop(node_hash)
107 def _reconnect(self):
108 """Close the SSH connection and open it again."""
111 self.disconnect(node)
113 logger.debug('Reconnecting peer done: {}'.
114 format(self._ssh.get_transport().getpeername()))
116 def exec_command(self, cmd, timeout=10):
117 """Execute SSH command on a new channel on the connected Node.
119 :param cmd: Command to run on the Node.
120 :param timeout: Maximal time in seconds to wait until the command is
121 done. If set to None then wait forever.
124 :return return_code, stdout, stderr
125 :rtype: tuple(int, str, str)
126 :raise SSHTimeout: If command is not finished in timeout time.
129 stdout = StringIO.StringIO()
130 stderr = StringIO.StringIO()
132 chan = self._ssh.get_transport().open_session(timeout=5)
133 except AttributeError:
135 chan = self._ssh.get_transport().open_session(timeout=5)
138 chan = self._ssh.get_transport().open_session(timeout=5)
139 chan.settimeout(timeout)
140 logger.trace('exec_command on {0}: {1}'
141 .format(self._ssh.get_transport().getpeername(), cmd))
143 chan.exec_command(cmd)
144 while not chan.exit_status_ready() and timeout is not None:
145 if chan.recv_ready():
146 stdout.write(chan.recv(self.__MAX_RECV_BUF))
148 if chan.recv_stderr_ready():
149 stderr.write(chan.recv_stderr(self.__MAX_RECV_BUF))
151 if time() - start > timeout:
153 'Timeout exception.\n'
154 'Current contents of stdout buffer: {0}\n'
155 'Current contents of stderr buffer: {1}\n'
156 .format(stdout.getvalue(), stderr.getvalue())
160 return_code = chan.recv_exit_status()
162 while chan.recv_ready():
163 stdout.write(chan.recv(self.__MAX_RECV_BUF))
165 while chan.recv_stderr_ready():
166 stderr.write(chan.recv_stderr(self.__MAX_RECV_BUF))
169 logger.trace('exec_command on {0} took {1} seconds'.format(
170 self._ssh.get_transport().getpeername(), end-start))
172 logger.trace('chan_recv/_stderr took {} seconds'.format(time()-end))
174 logger.trace('return RC {}'.format(return_code))
175 logger.trace('return STDOUT {}'.format(stdout.getvalue()))
176 logger.trace('return STDERR {}'.format(stderr.getvalue()))
177 return return_code, stdout.getvalue(), stderr.getvalue()
179 def exec_command_sudo(self, cmd, cmd_input=None, timeout=30):
180 """Execute SSH command with sudo on a new channel on the connected Node.
182 :param cmd: Command to be executed.
183 :param cmd_input: Input redirected to the command.
184 :param timeout: Timeout.
185 :return: return_code, stdout, stderr
189 >>> from ssh import SSH
191 >>> ssh.connect(node)
192 >>> # Execute command without input (sudo -S cmd)
193 >>> ssh.exec_command_sudo("ifconfig eth0 down")
194 >>> # Execute command with input (sudo -S cmd <<< "input")
195 >>> ssh.exec_command_sudo("vpp_api_test", "dump_interface_table")
197 if cmd_input is None:
198 command = 'sudo -S {c}'.format(c=cmd)
200 command = 'sudo -S {c} <<< "{i}"'.format(c=cmd, i=cmd_input)
201 return self.exec_command(command, timeout)
203 def interactive_terminal_open(self, time_out=30):
204 """Open interactive terminal on a new channel on the connected Node.
206 :param time_out: Timeout in seconds.
207 :return: SSH channel with opened terminal.
209 .. warning:: Interruptingcow is used here, and it uses
210 signal(SIGALRM) to let the operating system interrupt program
211 execution. This has the following limitations: Python signal
212 handlers only apply to the main thread, so you cannot use this
213 from other threads. You must not use this in a program that
214 uses SIGALRM itself (this includes certain profilers)
216 chan = self._ssh.get_transport().open_session()
219 chan.settimeout(int(time_out))
220 chan.set_combine_stderr(True)
223 while not buf.endswith((":~$ ", "~]$ ")):
225 chunk = chan.recv(self.__MAX_RECV_BUF)
229 if chan.exit_status_ready():
230 logger.error('Channel exit status ready')
232 except socket.timeout:
233 raise Exception('Socket timeout: {0}'.format(buf))
236 def interactive_terminal_exec_command(self, chan, cmd, prompt):
237 """Execute command on interactive terminal.
239 interactive_terminal_open() method has to be called first!
241 :param chan: SSH channel with opened terminal.
242 :param cmd: Command to be executed.
243 :param prompt: Command prompt, sequence of characters used to
244 indicate readiness to accept commands.
245 :return: Command output.
247 .. warning:: Interruptingcow is used here, and it uses
248 signal(SIGALRM) to let the operating system interrupt program
249 execution. This has the following limitations: Python signal
250 handlers only apply to the main thread, so you cannot use this
251 from other threads. You must not use this in a program that
252 uses SIGALRM itself (this includes certain profilers)
254 chan.sendall('{c}\n'.format(c=cmd))
256 while not buf.endswith(prompt):
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 raise Exception('Socket timeout: {0}'.format(buf))
267 tmp = buf.replace(cmd.replace('\n', ''), '')
273 def interactive_terminal_close(chan):
274 """Close interactive terminal SSH channel.
276 :param: chan: SSH channel to be closed.
280 def scp(self, local_path, remote_path):
281 """Copy files from local_path to remote_path.
283 connect() method has to be called first!
285 logger.trace('SCP {0} to {1}:{2}'.format(
286 local_path, self._ssh.get_transport().getpeername(), remote_path))
287 # SCPCLient takes a paramiko transport as its only argument
288 scp = SCPClient(self._ssh.get_transport())
290 scp.put(local_path, remote_path)
293 logger.trace('SCP took {0} seconds'.format(end-start))
296 def exec_cmd(node, cmd, timeout=600, sudo=False):
297 """Convenience function to ssh/exec/return rc, out & err.
299 Returns (rc, stdout, stderr).
302 raise TypeError('Node parameter is None')
304 raise TypeError('Command parameter is None')
306 raise ValueError('Empty command parameter')
311 except SSHException as err:
312 logger.error("Failed to connect to node" + str(err))
313 return None, None, None
317 (ret_code, stdout, stderr) = ssh.exec_command(cmd, timeout=timeout)
319 (ret_code, stdout, stderr) = ssh.exec_command_sudo(cmd,
321 except SSHException as err:
323 return None, None, None
325 return ret_code, stdout, stderr
328 def exec_cmd_no_error(node, cmd, timeout=600, sudo=False):
329 """Convenience function to ssh/exec/return out & err.
331 Verifies that return code is zero.
333 Returns (stdout, stderr).
335 (ret_code, stdout, stderr) = exec_cmd(node, cmd, timeout=timeout, sudo=sudo)
336 assert_equal(ret_code, 0, 'Command execution failed: "{}"\n{}'.
338 return stdout, stderr