I'm starting the initial phase of an official Hudson installation for my employer.
One thing about Hudson is that it is updated regularly, and I am not sure whether to recommend updating regularly, occasionally, or to update if and only if the update fixes a security bug (or a new feature is a Must Have from the point of view of my users).
What do other people do?
(We are not interested in the paid support)
We only update on demand. For this we monitor the release rss feed, that reports on Server and plugin releases. So far we usually updated the server because we wanted to install a plugin, that was dependent on a newer version. Otherwise, go with "Never change a running system". keeping up with the newest build (or following a few weeks behind on a weekly basis, is too much work for us). The risk that something doesn't work after an update is too big.
Currently we are updating way more often than quarterly, since we use lot's of plugins and are still in the buildup phase of a rather complex system (build, deploy, and (functional) tests in a mixed Windows/Unix environment).
Updates will definitely happen less frequently when the system is set up completely and Hudson maintenance slows down. In addition we will then have to comply more closely to corporate guidelines regarding Software Changes Request procedures.
We keep a test server running the very latest hudson. It just runs some simple Hello World type builds, uses the plugins we depend on e.g. google calendar, performance plugin and so on. If that deploys, builds work and publish results then we'll apply that version to production hudson node. We do this no more often than quarterly. We have very few plugins, are not integrated with AD and connect only to subversion repos. Not much to change and week keep. I've seen very few regressions in newer versions of hudson but I've been caught out recently with different strings indicating success in the RSS feed (it used to just say "SUCCESS". But that's just a case of making sure all your jobs run after an upgrade. We've only ever needed to upgrade because of a plugin we wanted wanting/requiring a particular version.
Another team I know keep their hudson 1 version behind the current release and they take these new versions on a weekly basis. Again they don't seem to have any problems with this.
I update whenever there's an update to take. Either that or I get fidgety and lose sleep :)
Fortunately, Hudson has the magical ability to rollback the latest update to the last one. This works unbelievably well as you can update - find an error or configuration problem, and undo the update with only a little downtime.
Most of the time updates just work, so its worth always updating to get the latest toys simply because you can - safely with the rollback feature. If the rollback wasn't there I'd consider saying "don't touch it 'cos that's when you'll break it".
