Managing many hosts is quite challenging task. There are many tools to solve the problem. My favorite is pdsh.

Running a command across a set of hosts is as simple as following:

# pdsh -w 192.168.177.[201-208] -R ssh reboot

Together with dshbak (which is a part of pdsh package) you can do even cooler things. Like, check which systems have yum:

# pdsh -w 192.168.177.[201-208] -R ssh "which yum" | dshbak -c
----------------
192.168.177.[201-203]
----------------
/usr/bin/yum 

Or which systems run older version of MySQL

# pdsh -w 192.168.177.[201-208] -R ssh "mysql -e \"SHOW VARIABLES LIKE 'version'\""  | dshbak -c
----------------
192.168.177.[201-203]
----------------
Variable_name   Value
version 5.6.19
----------------
192.168.177.[204-208]
----------------
Variable_name   Value
version 5.5.38

To make pdsh …

I’ve been playing around with some quick system automation scripts that are handy to use when you don’t want / need to setup a chef or puppet action. I like to keep all of my hostnames and login details in a MySQL database (a cmdb actually) but for this example we’ll just use a couple of nested lists. This script executes commands in parallel across the hosts you choose in the menu system via the “pdsh” command, so make sure you have that installed before running. Alternately you can change the command call to use ssh instead of pdsh for a serialized execution, but that’s not as fun or fast. With some customizations here and there you can expand this to operate parallelized jobs for simplifying daily work in database administration, usage reporting, log file parsing, or other system automation as you see fit. Here’s the code. Comments welcome as always!

#!/usr/bin/env python
## NAME: menu_parallel_execution.py
## DATE: …