使用 Paramiko invoke_shell/send/recv 读取命令输出永远不会完成

Question

我正在尝试在 Paramiko 中使用 send/recv 函数。据我所见，该行抛出超时异常

Evaluating: self.shell.recv(1024) did not finish after 3.00 seconds.

tmp = shell.recv(1024)

函数实现有什么问题？我的 while True 退出条件是异常，如何更改为无异常退出？

完整代码：

self.shell = self.SSHConnect(ip, username, password)

def SSHConnect(self, ip, username, passowrd):
    ssh = paramiko.SSHClient()
    LOGGER.debug(msg="Open SSH Client to :" + str(ip))
    try:
        ssh.set_missing_host_key_policy(policy=paramiko.AutoAddPolicy())
        ssh.connect(ip, port=22, username=username, password=passowrd, allow_agent=False, look_for_keys=True)
        if self.device_type != 'linux_host':
            session = ssh.invoke_shell()
            return session
    except Exception as ex:
        LOGGER.critical(msg="SSH Client wasn't established! Device name : " + str(self.device_name))
        return None 
    
    LOGGER.info(msg="Open SSH Client to :" + str(ip) + " established!")
    return ssh

def run_command(self,cmd):
    # New run command without throwing exception at the end:
    LOGGER.debug('Start new Run command with cmd =  ' + str(cmd))
    try:
        #Check the shell is activated before sending command:
        LOGGER.debug('Check the shell is activated before sending command: ' + cmd)
        if self.shell.get_transport().active:
            LOGGER.debug('Shell is Activated ! Running the command ')
            if self.device_type == 'linux_host':
                stdin, stdout, stderr = self.shell.exec_command(cmd)
            else:
                try:
                    #Command for switch of UFMAPL
                    LOGGER.debug('Sending command to UFMAPL/Switch with send()')
                    out = ''
                    self.shell.send(cmd)
                    while not self.shell.recv_ready():
                        time.sleep(3)
                    counter = 1
                    print('\ncommand is : ' + cmd + '\n' )
                    while True:
                        try:
                            print('iteration number is : #' + str(counter))
                            tmp = self.shell.recv(1024)
                            counter = counter + 1 
                            if not tmp:
                                break
                        except Exception as e:
                            break
                        out += tmp.decode("utf-8")
                        print('After iteration #' + str(counter) + ' out = ' + out + '\n\n')
                    ansi_escape = re.compile(r'\x1B\[[0-?]*[ -/]*[@-~]')
                    out = ansi_escape.sub('', out)
                    print('Printing final value before return : ' + str(out +'\n'))
                    return out
                except Exception as e:
                    LOGGER.error('Exception in send() : ' +str(e) )
                    return None
        else:
            LOGGER.critical('Shell is not activated !')
            return ""
    
        if stderr.read():
            LOGGER.critical('stderr is not empty which means the last command was failed, the command might not exist on host/switch ' )
            return stderr.read().decode('utf-8')
    
        out = stdout.read()
        if out:
            return out.decode("utf-8")
        else:
            LOGGER.critical('Run command sucussfully but return empty...')
            return out.decode("utf-8")
    except Exception as e:
        LOGGER.error('Exception received in run command : ' + str(e))

日志（打印到屏幕）：

IM HEREEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE


command is : enable


iteration number is : #1

After iteration #2 out =
UFM Appliance

UFM is configured as standalone.
UFM mode: Management.
RAID state is: Degraded ( DRIVE1:Online,SpunUp, DRIVE2:Failed )
smg-ib-apl008-gen2 [ mgmt-sa ] >


iteration number is : #2

After iteration #3 out =
UFM Appliance

UFM is configured as standalone.
UFM mode: Management.
RAID state is: Degraded ( DRIVE1:Online,SpunUp, DRIVE2:Failed )
smg-ib-apl008-gen2 [ mgmt-sa ] > e


iteration number is : #3

After iteration #4 out =
UFM Appliance

UFM is configured as standalone.
UFM mode: Management.
RAID state is: Degraded ( DRIVE1:Online,SpunUp, DRIVE2:Failed )
smg-ib-apl008-gen2 [ mgmt-sa ] > enable
smg-ib-a


iteration number is : #4

After iteration #5 out = 
UFM Appliance

UFM is configured as standalone.
UFM mode: Management.
RAID state is: Degraded ( DRIVE1:Online,SpunUp, DRIVE2:Failed )
smg-ib-apl008-gen2 [ mgmt-sa ] > enable
smg-ib-apl00


iteration number is : #5

After iteration #6 out =
UFM Appliance

UFM is configured as standalone.
UFM mode: Management.
RAID state is: Degraded ( DRIVE1:Online,SpunUp, DRIVE2:Failed )
smg-ib-apl008-gen2 [ mgmt-sa ] > enable
smg-ib-apl008-gen2 [ mgmt-sa ] #


iteration number is : #6

如您所见，调试器卡在 iteration #6（冻结）。为什么它会冻结并且不发送输出？

环境详细信息：

Windows 10
Eclipse 最新

如有任何帮助，我将不胜感激。如果您需要更多详细信息，请告诉我。

Answer 1

您的代码到了服务器停止等待另一个输入的地步。同时你等待服务器输出一些东西。它永远不会。这叫做 deadlock.

您可能已经预料到第一个命令执行已完成的某种信号。没有这样的信号。您正在使用“shell”（SSHClient.invoke_shell）。 shell 是一个带有输入和输出的黑盒子。除了输出之外没有其他信号，wihhc 你已经在阅读了。

“shell”不应用于自动执行命令。对于命令自动化，有“exec”通道（Paramiko 中的SSHClient.exec_command）。

虽然我知道对于某些特殊设备，您的服务器似乎是什么，您可能没有任何其他选择（请参阅）。此外，我不确定 enable 命令是如何工作的。是否已经完成的命令，或者是否开始了一种新的 shell，它仍然是运行，正在等待子命令。

所以最后你所能做的就是解析输出，等待命令提示符(smg-ib-apl008-gen2 [ mgmt-sa ] #)。

是的，它很丑。您正在尝试自动化一些不适合自动化的东西。也许您的服务器有更好的 API 然后 enable shell 命令，这将更好地实现自动化。但这是另一个问题。从 SSH/Python/Paramiko 的角度来看，没有更好的解决方案，如果您需要坚持在 shell.

中执行 enable 命令

使用 Paramiko invoke_shell/send/recv 读取命令输出永远不会完成

Reading command output with Paramiko invoke_shell/send/recv never finishes

python

ssh

shell

paramiko

完整代码：