How to automatically restart a service on failure in Linux

Question

On Windows, you can set what should happen if/when a service fails. Is there a standard way of achieving the same thing on Linux (CentOS in particular)?

A bigger part of my question is: how do you handle sockets that have been left open - for example in TIME_WAIT, FIN_WAIT1, etc states.

At the moment if the service I am developing crashes, I have to wait for the sockets to clear or change the listen port before I can then manually restart it.

Thanks for your help.

Answer 1

monit is a great way to monitor and restart services when they fail--and you'll probably end up using this for other essential services (such as Apache). There's a nice article on nixCraft detailing how to use this for services specifically, although monit itself has many more functions beyond this.

As for the socket aspect, @galraen answered this spot on.

Answer 2

You can call setsockopt(2) for listening socket with SO_REUSEADDR, so you will be able to bind(2) it again without waiting for expiring all connections. Another possibility: drop connections from kernel. FreeBSD have tcpdrop command for this, don't know about Linux.

Answer 3

If your linux distro uses Upstart instead of SysV init, then the respawn keyword does this.

http://upstart.ubuntu.com/cookbook/#respawn