Does paramiko close ssh connection on a non-paramiko exception

Question

I'm debugging some code, which is going to result in me constantly logging in / out of some external sftp servers. Does anyone know if paramiko automatically closes a ssh / sftp session on the external server if a non-paramiko exception is raised in the code? I can't find it in the docs and as the connections have to be made fairly early in each iteration I don't want to end up with 20 open connections.

Answer 1

SSHClient() can be used as a context manager, so you can do

with SSHClient() as ssh:
   ssh.connect(...)
   ssh.exec_command(...)

and not close manually.

Answer 2

No, paramiko will not automatically close the ssh / sftp session. It doesn't matter if the exception was generated by paramiko code or otherwise; there is nothing in the paramiko code that catches any exceptions and automatically closes them, so you have to do it yourself.

You can ensure that it gets closed by wrapping it in a try/finally block like so:

client = None
try:
    client = SSHClient()
    client.load_system_host_keys()
    client.connect('ssh.example.com')
    stdin, stdout, stderr = client.exec_command('ls -l')
finally:
    if client:
        client.close()