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 interruptingcow import timeout as icTimeout
25 from robot.api import logger
26 from robot.utils.asserts import assert_equal
28 __all__ = ["exec_cmd", "exec_cmd_no_error"]
34 """Contains methods for managing and using SSH connections."""
36 __MAX_RECV_BUF = 10*1024*1024
37 __existing_connections = {}
45 """Get IP address and port hash from node dictionary.
47 :param node: Node in topology.
49 :return: IP address and port for the specified node.
53 return hash(frozenset([node['host'], node['port']]))
55 def connect(self, node):
56 """Connect to node prior to running exec_command or scp.
58 If there already is a connection to the node, this method reuses it.
61 node_hash = self._node_hash(node)
62 if node_hash in SSH.__existing_connections:
63 self._ssh = SSH.__existing_connections[node_hash]
64 logger.debug('reusing ssh: {0}'.format(self._ssh))
68 if 'priv_key' in node:
69 pkey = RSAKey.from_private_key(
70 StringIO.StringIO(node['priv_key']))
72 self._ssh = paramiko.SSHClient()
73 self._ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
75 self._ssh.connect(node['host'], username=node['username'],
76 password=node.get('password'), pkey=pkey,
79 self._ssh.get_transport().set_keepalive(10)
81 SSH.__existing_connections[node_hash] = self._ssh
83 logger.trace('connect took {} seconds'.format(time() - start))
84 logger.debug('new ssh: {0}'.format(self._ssh))
86 logger.debug('Connect peer: {0}'.
87 format(self._ssh.get_transport().getpeername()))
88 logger.debug('Connections: {0}'.format(str(SSH.__existing_connections)))
90 def disconnect(self, node):
91 """Close SSH connection to the node.
93 :param node: The node to disconnect from.
96 node_hash = self._node_hash(node)
97 if node_hash in SSH.__existing_connections:
98 logger.debug('Disconnecting peer: {}, {}'.
99 format(node['host'], node['port']))
100 ssh = SSH.__existing_connections.pop(node_hash)
103 def _reconnect(self):
104 """Close the SSH connection and open it again."""
107 self.disconnect(node)
109 logger.debug('Reconnecting peer done: {}'.
110 format(self._ssh.get_transport().getpeername()))
112 def exec_command(self, cmd, timeout=10):
113 """Execute SSH command on a new channel on the connected Node.
115 :param cmd: Command to run on the Node.
116 :param timeout: Maximal time in seconds to wait until the command is
117 done. If set to None then wait forever.
120 :return return_code, stdout, stderr
121 :rtype: tuple(int, str, str)
122 :raise socket.timeout: If command is not finished in timeout time.
125 stdout = StringIO.StringIO()
126 stderr = StringIO.StringIO()
128 chan = self._ssh.get_transport().open_session(timeout=5)
129 except AttributeError:
131 chan = self._ssh.get_transport().open_session(timeout=5)
134 chan = self._ssh.get_transport().open_session(timeout=5)
135 chan.settimeout(timeout)
136 logger.trace('exec_command on {0}: {1}'
137 .format(self._ssh.get_transport().getpeername(), cmd))
139 chan.exec_command(cmd)
140 while not chan.exit_status_ready() and timeout is not None:
141 if chan.recv_ready():
142 stdout.write(chan.recv(self.__MAX_RECV_BUF))
144 if chan.recv_stderr_ready():
145 stderr.write(chan.recv_stderr(self.__MAX_RECV_BUF))
147 if time() - start > timeout:
148 raise socket.timeout(
149 'Timeout exception.\n'
150 'Current contents of stdout buffer: {0}\n'
151 'Current contents of stderr buffer: {1}\n'
152 .format(stdout.getvalue(), stderr.getvalue())
156 return_code = chan.recv_exit_status()
158 while chan.recv_ready():
159 stdout.write(chan.recv(self.__MAX_RECV_BUF))
161 while chan.recv_stderr_ready():
162 stderr.write(chan.recv_stderr(self.__MAX_RECV_BUF))
165 logger.trace('exec_command on {0} took {1} seconds'.format(
166 self._ssh.get_transport().getpeername(), end-start))
168 logger.trace('chan_recv/_stderr took {} seconds'.format(time()-end))
170 logger.trace('return RC {}'.format(return_code))
171 logger.trace('return STDOUT {}'.format(stdout.getvalue()))
172 logger.trace('return STDERR {}'.format(stderr.getvalue()))
173 return return_code, stdout.getvalue(), stderr.getvalue()
175 def exec_command_sudo(self, cmd, cmd_input=None, timeout=30):
176 """Execute SSH command with sudo on a new channel on the connected Node.
178 :param cmd: Command to be executed.
179 :param cmd_input: Input redirected to the command.
180 :param timeout: Timeout.
181 :return: return_code, stdout, stderr
185 >>> from ssh import SSH
187 >>> ssh.connect(node)
188 >>> # Execute command without input (sudo -S cmd)
189 >>> ssh.exec_command_sudo("ifconfig eth0 down")
190 >>> # Execute command with input (sudo -S cmd <<< "input")
191 >>> ssh.exec_command_sudo("vpp_api_test", "dump_interface_table")
193 if cmd_input is None:
194 command = 'sudo -S {c}'.format(c=cmd)
196 command = 'sudo -S {c} <<< "{i}"'.format(c=cmd, i=cmd_input)
197 return self.exec_command(command, timeout)
199 def interactive_terminal_open(self, time_out=10):
200 """Open interactive terminal on a new channel on the connected Node.
202 :param time_out: Timeout in seconds.
203 :return: SSH channel with opened terminal.
205 .. warning:: Interruptingcow is used here, and it uses
206 signal(SIGALRM) to let the operating system interrupt program
207 execution. This has the following limitations: Python signal
208 handlers only apply to the main thread, so you cannot use this
209 from other threads. You must not use this in a program that
210 uses SIGALRM itself (this includes certain profilers)
212 chan = self._ssh.get_transport().open_session()
215 chan.settimeout(int(time_out))
219 with icTimeout(time_out, exception=RuntimeError):
220 while not buf.endswith(':~$ '):
221 if chan.recv_ready():
222 buf = chan.recv(4096)
224 raise Exception('Open interactive terminal timeout.')
228 def interactive_terminal_exec_command(chan, cmd, prompt,
230 """Execute command on interactive terminal.
232 interactive_terminal_open() method has to be called first!
234 :param chan: SSH channel with opened terminal.
235 :param cmd: Command to be executed.
236 :param prompt: Command prompt, sequence of characters used to
237 indicate readiness to accept commands.
238 :param time_out: Timeout in seconds.
239 :return: Command output.
241 .. warning:: Interruptingcow is used here, and it uses
242 signal(SIGALRM) to let the operating system interrupt program
243 execution. This has the following limitations: Python signal
244 handlers only apply to the main thread, so you cannot use this
245 from other threads. You must not use this in a program that
246 uses SIGALRM itself (this includes certain profilers)
248 chan.sendall('{c}\n'.format(c=cmd))
251 with icTimeout(time_out, exception=RuntimeError):
252 while not buf.endswith(prompt):
253 if chan.recv_ready():
254 buf += chan.recv(4096)
256 raise Exception("Exec '{c}' timeout.".format(c=cmd))
257 tmp = buf.replace(cmd.replace('\n', ''), '')
258 return tmp.replace(prompt, '')
261 def interactive_terminal_close(chan):
262 """Close interactive terminal SSH channel.
264 :param: chan: SSH channel to be closed.
268 def scp(self, local_path, remote_path):
269 """Copy files from local_path to remote_path.
271 connect() method has to be called first!
273 logger.trace('SCP {0} to {1}:{2}'.format(
274 local_path, self._ssh.get_transport().getpeername(), remote_path))
275 # SCPCLient takes a paramiko transport as its only argument
276 scp = SCPClient(self._ssh.get_transport())
278 scp.put(local_path, remote_path)
281 logger.trace('SCP took {0} seconds'.format(end-start))
284 def exec_cmd(node, cmd, timeout=600, sudo=False):
285 """Convenience function to ssh/exec/return rc, out & err.
287 Returns (rc, stdout, stderr).
290 raise TypeError('Node parameter is None')
292 raise TypeError('Command parameter is None')
294 raise ValueError('Empty command parameter')
299 except Exception as err:
300 logger.error("Failed to connect to node" + str(err))
301 return None, None, None
305 (ret_code, stdout, stderr) = ssh.exec_command(cmd, timeout=timeout)
307 (ret_code, stdout, stderr) = ssh.exec_command_sudo(cmd,
309 except Exception as err:
311 return None, None, None
313 return ret_code, stdout, stderr
316 def exec_cmd_no_error(node, cmd, timeout=600, sudo=False):
317 """Convenience function to ssh/exec/return out & err.
319 Verifies that return code is zero.
321 Returns (stdout, stderr).
323 (ret_code, stdout, stderr) = exec_cmd(node, cmd, timeout=timeout, sudo=sudo)
324 assert_equal(ret_code, 0, 'Command execution failed: "{}"\n{}'.
326 return stdout, stderr