If you need to maintain multiple hosts, you know how boring it is to repeat the exact same task on all of them. I'm currently using PlanetLab as part of a class assignment and I'm facing this problem because I need to set up around 10 machines and execute the same commands on all of them.
vxargs is a nice Python script that eases this task. It lets you run a command parametrizing it with a given set of strings (e.g. host names), similar to what find's -exec flag does. First of all, you construct a file with the list of host names you need to control and then feed it to the script alongside the command you need to execute. For example, to upload a dist.tgz file to all the servers:
vxargs -a hosts.list -o /tmp/result scp dist.tgz {}:
The utility will replace the {} substring with each line in hosts.list and will execute the command. The nice thing is that vxargs runs all tasks in parallel, maximizing efficience. During execution, its cursed-based interface shows the progress of each command. And when all jobs are over, you will find their output (stdout and stderr) as well as their exit code in the /tmp/result directory. Fairly useful.
Despite that manually installing vxargs is easy, there is now a vxargs package in pkgsrc.
Really nice! Thanks for the pointer.
ReplyDeleteThe dsh program from clusterit (clusterit.sf.net or pkgsrc/parallel/clusterit) is similar to this; it runs a given command on a bunch of hosts. The clusterit package contains more useful commands to manipulate multiple hosts together.
ReplyDeleteAnd for real automated multiple-machines-administration, there is cfengine (cfengine.org, pkgsrc/sysutils/cfengine2), which is rather complex but extremely powerful.