Question

I’m using Paramiko to try and crawl through a list of hosts. The code will work until one of the hosts in the list is unavailable. It produces this error.

  File "remote.py", line 12, in <module>
  ssh.connect(i, username='user', password='pass')
  File "/usr/local/lib/python2.7/dist-packages/paramiko/client.py", line 296, in connect  
  sock.connect(addr)
  File "/usr/lib/python2.7/socket.py", line 224, in meth
  return getattr(self._sock,name)(*args) 
  socket.error: [Errno 113] No route to host

My Code:

#!/usr/bin/python
import paramiko

host = ['cpu1','cpu2','cpu3']

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())

for i in host:
    str(i)
    ssh.connect(i, username='user', password='pass')
    stdin, stdout, stderr = ssh.exec_command('w')
    print stdout.readlines()
    ssh.close()

I’m wanting the script to run through and execute the command. If it cannot connect to the host then skip and go to the next. Am I missing an if statement with some Paramiko parameters?

Answer 1

you can try catching the exception, handling and maybe continuing if you so desire.

import paramiko

host = ['cpu1','cpu2','cpu3']

ssh = paramiko.SSHClient()
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())

for i in host:
    str(i)
    try:
        ssh.connect(i, username='user', password='pass')
        stdin, stdout, stderr = ssh.exec_command('w')
        print stdout.readlines()
        ssh.close()
    except Exception as ex:
        print "Excetion: %s" % str(ex)

Always properly handle exceptions don’t blindly escape them using pass, it can lead to hard to find bugs.