DebAWeek: clusterssh

There are many ways to manage large numbers of computers. The premise of clusterssh is to define clusters of computers that can be connected to through ssh (telnet and rsh are also supported) so that commands can be passed to all sessions at once. What separates clusterssh from other solutions is that it displays all windows at once and allows the user to enter commands into any one window as well as all windows quite easily. These features make it better than using terminal programs with tabs that the user must toggle input between 1 and all sessions.

Here’s how I installed and configured clusterssh:

• sudo apt-get install clusterssh
• cssh -u > $HOME/.csshrc
• nano $HOME/.csshrc
• at the top of the file (above “# Configuration dump produced by ‘cssh -u’”):

  clusters = cluster1 cluster2 cluster3
cluster1 = computer1 computer2
cluster2 = computer3 computer4
cluster3 = cluster1 cluster2 computer5

At this point I could just type: cssh cluster3 and have 5 terminal windows appear. What’s nice about the cluster setup is that clusters can be defined by particular tasks that need to be done. So if there’s 2 systems you’re always restarting the same service on you can configure them as 1 cluster and have the computers present in other clusters, like one used for software updates.

An article called Use ssh on multiple servers at one time has numerous suggestions on other methods to accomplish the same tasks as clusterssh in its comments. Some of these methods I’ve tried and others I haven’t but I have yet to find anything as good as clusterssh.