Event when one remote command has finished

[f380cedric]

Hi pkittenis,

Thx for your work!

I have to run commands that do not terminate on multiple remotes.
I am interested in getting notified when any remote command finished (e.g. the command encountered an unexpected error and exited, the process crashed, etc.).

While browsing the documentation,
I could not find any other way than polling around this snipped:

try:
    client.join(output, timeout=5)
except Timeout as ex:
    # Some commands timed out
    finished_output = ex.args[2]
    unfinished_output = ex.args[3]
else:
    # No timeout, all commands finished within five seconds
    finished_output = output
    unfinished_output = None

and checking if finished_output is populated.
Do you know any other way?

Regards

[pkittenis]

Hi,

Thanks for the interest. Short answer is no. Callback support is tracked by #275.

It could be done client side by spawning callback greenlets on top of SSHClient.wait_finished. Eg, something like:

from gevent import spawn


def my_cb(host_out):
    try:
        host_out.client.wait_finished()
    except Exception as ex:
        exc = ex
    else:
        exc = None
    print(f"Command on host {host_out.host} exited with error code {host_out.exit_code}, exception {exc}")


output = client.run_command(<..>)
callbacks = [spawn(my_cb, host_out) for host_out in output]

Can similarly do something other than print in the callback.

wait_finished will block the current greenlet. Anything after it will only be run if the command terminates for whatever reason. wait_finished needs to be run in a new greenlet to run in background.