parallel SSH in perl

Question

I am trying to create a script in perl which can ssh to multiple hosts (500+), execute a desired command, and show output on the screen. I have done this with the Net::OpenSSH module, as ssh-keys are not configured and I am not allowed to configure those. So, I have to use a thing which can supply the password while doing ssh.

Due to the many connections, it takes considerable time while doing the thing. I searched for "parallel ssh in perl" and discovered that there is a module for opening parallel ssh (Net::OpenSSH:Parallel), but I read somewhere on some forums that I cannot capture output with this module like I can capture using Net::OpenSSH ($ssh->caputre(ls)).

So, how can I accomplish parallel ssh in a more expedient manner? Also, I welcome any other suggestions I can use to save time. Would using Net:OpenSSH in threads save my time or will it work exactly like parallel?

Answer 1

You can fork your program and manage the forks with something like Parallel::ForkManager. Then do the SSH work + capture using Net::OpenSSH and display the results to the screen. You'll need to be careful with your IO though since all those processes trying to write to STDOUT/STDERR at the same time will get garbled results. You'll need to do something like the answer from this question (pipes between parent and child processes): fork() and STDOUT/STDERR to the console from child processes

Parallel programming is harder than serial, so be prepared for some fun :)

Answer 2

One way is to use a shell script to execute your perl script:

#!/bin/bash

for host in $(cat myhosts)
do
  perl myperl.pl $host $1 $2 &
done 

where myhosts is a file containing 500+ host names