CODEWITHSUNDEEP
pythonsshssh-agentpssh
Arun Srinivasan
Arun Srinivasan

Reputation: 131

Getting "TypeError: 'NoneType' object is not iterable" while doing parallel ssh

I am trying to do parallel ssh on servers. While doing this, i am getting "TypeError: 'NoneType' object is not iterable" this error. Kindly help.

My script is below

from pssh import ParallelSSHClient
from pssh.exceptions import AuthenticationException, UnknownHostException, ConnectionErrorException

def parallelsshjob():
        client = ParallelSSHClient(['10.84.226.72','10.84.226.74'], user = 'root', password = 'XXX')
        try:
                output = client.run_command('racadm getsvctag', sudo=True)
                print output
        except (AuthenticationException, UnknownHostException, ConnectionErrorException):
                pass
        #print output

if __name__ == '__main__':
        parallelsshjob()

And the Traceback is below

Traceback (most recent call last):
  File "parallelssh.py", line 17, in <module>
    parallelsshjob()
  File "parallelssh.py", line 10, in parallelsshjob
    output = client.run_command('racadm getsvctag', sudo=True)
  File "/Library/Python/2.7/site-packages/pssh/pssh_client.py", line 520, in run_command
    raise ex
TypeError: 'NoneType' object is not iterable

Help me with the solution and also suggest me to use ssh-agent in this same script. Thanks in advance.

Upvotes: 0

Views: 977

Answers (2)

danny
danny

Reputation: 5270

This was seemingly a regression in the 0.92.0 version of the library which is now resolved in 0.92.1. Previous versions also work. OpenSSH config should not be a dependency.

To answer your SSH agent question, if there is one running and enabled in the user session it gets used automatically. If you would prefer to provide a private key programmatically can do the following

from pssh import ParallelSSHClient
from pssh.utils import load_private_key
pkey = load_private_key('my_private_key')
client = ParallelSSHClient(hosts, pkey=pkey)

Can also provide an agent with multiple keys programmatically, per below

from pssh import ParallelSSHClient
from pssh.utils import load_private_key
from pssh.agent import SSHAgent
pkey = load_private_key('my_private_key')
agent = SSHAgent()
agent.add_key(pkey)
client = ParallelSSHClient(hosts, agent=agent)

See documentation for more examples.

Upvotes: 0

user94559
user94559

Reputation: 60153

From reading the code and debugging a bit on my laptop, I believe the issue is that you don't have a file called ~/.ssh/config. It seems that parallel-ssh has a dependency on OpenSSH configuration, and this is the error you get when that file is missing.

read_openssh_config returns None here: https://github.com/pkittenis/parallel-ssh/blob/master/pssh/utils.py#L79

In turn, SSHClient.__init__ blows up when trying to unpack the values it expects to receive: https://github.com/pkittenis/parallel-ssh/blob/master/pssh/ssh_client.py#L97.

The fix is presumably to get some sort of OpenSSH config file in place, but I'm sorry to say I know nothing about that.

EDIT

After cleaning up some of parallel-ssh's exception handling, here's a better stack trace for the error:

Traceback (most recent call last):
  File "test.py", line 11, in <module>
    parallelsshjob()
  File "test.py", line 7, in parallelsshjob
    output = client.run_command('racadm getsvctag', sudo=True)
  File "/Users/smarx/test/pssh/venv/lib/python2.7/site-packages/pssh/pssh_client.py", line 517, in run_command
    self.get_output(cmd, output)
  File "/Users/smarx/test/pssh/venv/lib/python2.7/site-packages/pssh/pssh_client.py", line 601, in get_output
    (channel, host, stdout, stderr, stdin) = cmd.get()
  File "/Users/smarx/test/pssh/venv/lib/python2.7/site-packages/gevent/greenlet.py", line 480, in get
    self._raise_exception()
  File "/Users/smarx/test/pssh/venv/lib/python2.7/site-packages/gevent/greenlet.py", line 171, in _raise_exception
    reraise(*self.exc_info)
  File "/Users/smarx/test/pssh/venv/lib/python2.7/site-packages/gevent/greenlet.py", line 534, in run
    result = self._run(*self.args, **self.kwargs)
  File "/Users/smarx/test/pssh/venv/lib/python2.7/site-packages/pssh/pssh_client.py", line 559, in _exec_command
    channel_timeout=self.channel_timeout)
  File "/Users/smarx/test/pssh/venv/lib/python2.7/site-packages/pssh/ssh_client.py", line 98, in __init__
    host, config_file=_openssh_config_file)
TypeError: 'NoneType' object is not iterable

Upvotes: 1

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