Automation should be second nature to a system administrator. I have a maxim that I try to live by: “If I can tell someone how to do it, I can tell a computer how to do it.” I put this into practice by automating everything I can.
Why is this so important? If you craft every machine by hand, then you wind up with a number of problems (or possible problems):
- Each machine is independently configured, and each machine is different. No two machines will be alike – which means instead of one machine replicated one hundred times, you’ll have one hundred different machines.
- Problems that exist on a machine may or may not exist on another – and may or may not get fixed when found. If machine alpha has a problem, how do you know that machine beta or machine charlie don’t have the same problem? How do you know the problem is fixed on all machines? You don’t.
- How do you know all required software is present? You don’t. It might be present on machine alpha, but not machine delta.
- How do you know all software is up to date and at the same revision? You don’t. If machine alpha and machine delta both have a particular software, maybe it is the same one and maybe not.
- How do you know if you’ve configured two machines in the same way? Maybe you missed a particular configuration requirement – which will only show up later as a problem or service outage.
- If you have to recover any given machine, how do you know it will be recovered to the same configuration? Often, the configuration may or may not be backed up – so then it has to be recreated. Are the same packages installed? The same set of software? The same patches?
To avoid these problems and more, automation should be a part of every system wherever possible. Automate the configuration – setup – reconfiguration – backups – and so forth. Don’t miss anything – and if you did, add the automation as soon as you know about it.
Other tools that help tremendously in this area are automatic installation tools: Red Hat Kickstart (as well as Spacewalk), Solaris Jumpstart, HP’s Ignite-UX, and OpenSUSE Autoyast. These systems can, if configured properly, automatically install a machine unattended.
When combined with a tool like cfengine or puppet, these automatic installations can be nearly complete – from turning the system on for the very first time to full operation without operator intervention. This automated install not only improves reliability, but can free up hours of your time.