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, 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}'.format(str(SSH.__existing_connections)))
96 self._reconnect(attempts-1)
100 def disconnect(self, node):
101 """Close SSH connection to the node.
103 :param node: The node to disconnect from.
106 node_hash = self._node_hash(node)
107 if node_hash in SSH.__existing_connections:
108 logger.debug('Disconnecting peer: {}, {}'.
109 format(node['host'], node['port']))
110 ssh = SSH.__existing_connections.pop(node_hash)
113 def _reconnect(self, attempts=0):
114 """Close the SSH connection and open it again."""
117 self.disconnect(node)
118 self.connect(node, attempts)
119 logger.debug('Reconnecting peer done: {}'.
120 format(self._ssh.get_transport().getpeername()))
122 def exec_command(self, cmd, timeout=10):
123 """Execute SSH command on a new channel on the connected Node.
125 :param cmd: Command to run on the Node.
126 :param timeout: Maximal time in seconds to wait until the command is
127 done. If set to None then wait forever.
130 :return return_code, stdout, stderr
131 :rtype: tuple(int, str, str)
132 :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 except AttributeError:
141 chan = self._ssh.get_transport().open_session(timeout=5)
144 chan = self._ssh.get_transport().open_session(timeout=5)
145 chan.settimeout(timeout)
146 logger.trace('exec_command on {0}: {1}'
147 .format(self._ssh.get_transport().getpeername(), cmd))
149 chan.exec_command(cmd)
150 while not chan.exit_status_ready() and timeout is not None:
151 if chan.recv_ready():
152 stdout.write(chan.recv(self.__MAX_RECV_BUF))
154 if chan.recv_stderr_ready():
155 stderr.write(chan.recv_stderr(self.__MAX_RECV_BUF))
157 if time() - start > timeout:
159 'Timeout exception.\n'
160 'Current contents of stdout buffer: {0}\n'
161 'Current contents of stderr buffer: {1}\n'
162 .format(stdout.getvalue(), stderr.getvalue())
166 return_code = chan.recv_exit_status()
168 while chan.recv_ready():
169 stdout.write(chan.recv(self.__MAX_RECV_BUF))
171 while chan.recv_stderr_ready():
172 stderr.write(chan.recv_stderr(self.__MAX_RECV_BUF))
175 logger.trace('exec_command on {0} took {1} seconds'.format(
176 self._ssh.get_transport().getpeername(), end-start))
178 logger.trace('chan_recv/_stderr took {} seconds'.format(time()-end))
180 logger.trace('return RC {}'.format(return_code))
181 logger.trace('return STDOUT {}'.format(stdout.getvalue()))
182 logger.trace('return STDERR {}'.format(stderr.getvalue()))
183 return return_code, stdout.getvalue(), stderr.getvalue()
185 def exec_command_sudo(self, cmd, cmd_input=None, timeout=30):
186 """Execute SSH command with sudo on a new channel on the connected Node.
188 :param cmd: Command to be executed.
189 :param cmd_input: Input redirected to the command.
190 :param timeout: Timeout.
191 :return: return_code, stdout, stderr
195 >>> from ssh import SSH
197 >>> ssh.connect(node)
198 >>> # Execute command without input (sudo -S cmd)
199 >>> ssh.exec_command_sudo("ifconfig eth0 down")
200 >>> # Execute command with input (sudo -S cmd <<< "input")
201 >>> ssh.exec_command_sudo("vpp_api_test", "dump_interface_table")
203 if cmd_input is None:
204 command = 'sudo -S {c}'.format(c=cmd)
206 command = 'sudo -S {c} <<< "{i}"'.format(c=cmd, i=cmd_input)
207 return self.exec_command(command, timeout)
209 def interactive_terminal_open(self, time_out=30):
210 """Open interactive terminal on a new channel on the connected Node.
212 :param time_out: Timeout in seconds.
213 :return: SSH channel with opened terminal.
215 .. warning:: Interruptingcow is used here, and it uses
216 signal(SIGALRM) to let the operating system interrupt program
217 execution. This has the following limitations: Python signal
218 handlers only apply to the main thread, so you cannot use this
219 from other threads. You must not use this in a program that
220 uses SIGALRM itself (this includes certain profilers)
222 chan = self._ssh.get_transport().open_session()
225 chan.settimeout(int(time_out))
226 chan.set_combine_stderr(True)
229 while not buf.endswith((":~$ ", "~]$ ")):
231 chunk = chan.recv(self.__MAX_RECV_BUF)
235 if chan.exit_status_ready():
236 logger.error('Channel exit status ready')
238 except socket.timeout:
239 raise Exception('Socket timeout: {0}'.format(buf))
242 def interactive_terminal_exec_command(self, chan, cmd, prompt):
243 """Execute command on interactive terminal.
245 interactive_terminal_open() method has to be called first!
247 :param chan: SSH channel with opened terminal.
248 :param cmd: Command to be executed.
249 :param prompt: Command prompt, sequence of characters used to
250 indicate readiness to accept commands.
251 :return: Command output.
253 .. warning:: Interruptingcow is used here, and it uses
254 signal(SIGALRM) to let the operating system interrupt program
255 execution. This has the following limitations: Python signal
256 handlers only apply to the main thread, so you cannot use this
257 from other threads. You must not use this in a program that
258 uses SIGALRM itself (this includes certain profilers)
260 chan.sendall('{c}\n'.format(c=cmd))
262 while not buf.endswith(prompt):
264 chunk = chan.recv(self.__MAX_RECV_BUF)
268 if chan.exit_status_ready():
269 logger.error('Channel exit status ready')
271 except socket.timeout:
272 raise Exception('Socket timeout: {0}'.format(buf))
273 tmp = buf.replace(cmd.replace('\n', ''), '')
279 def interactive_terminal_close(chan):
280 """Close interactive terminal SSH channel.
282 :param: chan: SSH channel to be closed.
286 def scp(self, local_path, remote_path):
287 """Copy files from local_path to remote_path.
289 connect() method has to be called first!
291 logger.trace('SCP {0} to {1}:{2}'.format(
292 local_path, self._ssh.get_transport().getpeername(), remote_path))
293 # SCPCLient takes a paramiko transport as its only argument
294 scp = SCPClient(self._ssh.get_transport(), socket_timeout=10)
296 scp.put(local_path, remote_path)
299 logger.trace('SCP took {0} seconds'.format(end-start))
302 def exec_cmd(node, cmd, timeout=600, sudo=False):
303 """Convenience function to ssh/exec/return rc, out & err.
305 Returns (rc, stdout, stderr).
308 raise TypeError('Node parameter is None')
310 raise TypeError('Command parameter is None')
312 raise ValueError('Empty command parameter')
317 except SSHException as err:
318 logger.error("Failed to connect to node" + str(err))
319 return None, None, None
323 (ret_code, stdout, stderr) = ssh.exec_command(cmd, timeout=timeout)
325 (ret_code, stdout, stderr) = ssh.exec_command_sudo(cmd,
327 except SSHException as err:
329 return None, None, None
331 return ret_code, stdout, stderr
334 def exec_cmd_no_error(node, cmd, timeout=600, sudo=False):
335 """Convenience function to ssh/exec/return out & err.
337 Verifies that return code is zero.
339 Returns (stdout, stderr).
341 (ret_code, stdout, stderr) = exec_cmd(node, cmd, timeout=timeout, sudo=sudo)
342 assert_equal(ret_code, 0, 'Command execution failed: "{}"\n{}'.
344 return stdout, stderr