How do I easily manage 22 almost identical Debian servers at once?

Question

So I have 22 servers, all running the same OS, the same user accounts, the same software and so on and so forth. The only actual differences are the IP address and the hostname. When programming, most people prefer having a central place with preferences for an element, and the same thing goes for servers. I need my servers easily manageable.

What I expect to be able to do is the following:

• Install software for all servers at once (This basically implies running a shell command on all machines)
• Manage the crontab of all servers centrally
• Manage the configuration files centrally (sshd_config, hosts and such)
• Monitor the servers, receive e-mail alerts if they go offline

Is there any simple software to do this, or do I have to make something myself? I know most of this can be done with a DNS server and a bit of scripting (all users use the same keyfiles for all servers, so a script calling ssh for all servers could do some of the things I need), but that's not the kind of solution I'm looking for. I'm looking for a web panel of some sort, or maybe even a Windows program or something.

Answer 1

Generally, a system like Chef or Puppet is the ideal/modern way to perform configuration management. Your various manifests/recipes/etc can be placed into a version control system like Git to manage changes to the configuration itself.

As an aside, if you also have Windows servers, Chef and Puppet can be used with Windows, although they are more commonly used with Linux-based operating systems. For Windows, System Center Configuration Manager, or even just scripts deployed via group policy, can be used to manage large groups of servers with relative ease. Also, management tools like Server Manager and ADAC in Windows Server 2012 have overall been greatly enhanced in terms of managing groups of servers from a centralized interface.