Robuste paramiko SSH Befehl Ausführung mit Timeout-Unterstützung

Question

Ich muss eine Methode in Python für Remote-SSH-Befehlsausführung, die Timeout (mit teilweiser Ausgabe von sowohl stdout und stderr im Falle von Timeout) unterstützt unterstützt. Ich habe hier viele Themen durchgespielt und konnte für dieses Problem keine vollständige Lösung finden.

Im Folgenden finden Sie meinen Vorschlag zu finden, wie die 3.

Answer 1

in Python zu erreichen

Ich verwende (tuned leicht) Thomas' solution for timeout, aber ein anderer Ansatz verwendet werden könnte, wenn nötig:

import paramiko 
import signal 

class Timeout: 
    def __init__(self, seconds=1, error_message='Timeout', exception_type=TimeoutError): 
     self.seconds = seconds 
     self.error_message = error_message + " after {seconds}".format(seconds=seconds) 
     self.exception_type = exception_type 

    def handle_timeout(self, signum, frame): 
     raise self.exception_type(self.error_message) 

    def __enter__(self): 
     signal.signal(signal.SIGALRM, self.handle_timeout) 
     signal.alarm(self.seconds) 

    def __exit__(self, type, value, traceback): 
     signal.alarm(0) 


def run_cmd(connection_info, cmd, timeout=5): 
    """ 
    Runs command via SSH, supports timeout and partian stdout/stderr gathering. 
    :param connection_info: Dict with 'hostname', 'username' and 'password' fields 
    :param cmd: command to run 
    :param timeout: timeout for command execution (does not apply to SSH session creation!) 
    :return: stdout, stderr, exit code from command execution. Exit code is -1 for timed out commands 
    """ 
    # Session creation can be done ous 
    client = paramiko.SSHClient() 
    client.load_system_host_keys() 
    client.connect(**connection_info) 
    channel = client.get_transport().open_session() # here TCP socket timeout could be tuned 
    out = "" 
    err = "" 
    ext = -1 # exit code -1 for timed out commands 
    channel.exec_command(cmd) 
    try: 
     with Timeout(timeout): 
      while True: 
       if channel.recv_ready(): 
        out += channel.recv(1024).decode() 
       if channel.recv_stderr_ready(): 
        err += channel.recv_stderr(1024).decode() 
       if channel.exit_status_ready() and not channel.recv_ready() and not channel.recv_stderr_ready(): 
        ext = channel.recv_exit_status() 
        break 
    except TimeoutError: 
     print("command timeout") 
    return out, err, ext 

Lass es uns jetzt testen:

from time import time 
def test(cmd, timeout): 
    credentials = {"hostname": '127.0.0.1', "password": 'password', "username": 'user'} 
    ts = time() 
    print("\n---\nRunning: " + cmd) 
    result = run_cmd(credentials, cmd, timeout) 
    print("...it took: {0:4.2f}s".format(time() - ts)) 
    print("Result: {}\n".format(str(result)[:200])) 

# Those should time out: 
test('for i in {1..10}; do echo -n "OUT$i "; sleep 0.5; done', 2) 
test('for i in {1..10}; do echo -n "ERR$i " >&2; sleep 0.5; done', 2) 
test('for i in {1..10}; do echo -n "ERR$i " >&2; echo -n "OUT$i "; sleep 0.5; done', 2) 

# Those should not time out: 
test('for i in {1..10}; do echo -n "OUT$i "; sleep 0.1; done', 2) 
test('for i in {1..10}; do echo -n "ERR$i " >&2; sleep 0.1; done', 2) 
test('for i in {1..10}; do echo -n "ERR$i " >&2; echo -n "OUT$i "; sleep 0.1; done', 2) 

# Large output testing, with timeout: 
test("cat /dev/urandom | base64 |head -n 1000000", 2) 
test("cat /dev/urandom | base64 |head -n 1000000 >&2", 2)