Puppet + Passenger
Simple answer: for the performance. We currently have over 150 servers (many of the virtual) to manage. Right now only a small subset of these servers is running the puppet client, but I'm looking forward to the point where we will manage all of them using puppet.
The puppet docs have to say this about scaling:
Mongrel scales much better than WEBrick, at least partially because it allows you to run multiple processes serving the same pool of clients on the same host. WEBrick only uses Ruby's threading, which does not scale beyond one processor, and it appears that WEBrick starts dropping connections beyond about 2 concurrent connections.
If you're getting connection-reset or End-of-file errors, you should try Mongrel. As more people try it and it proves to be stable, it will eventually become the preferred serving platform for the master.
While I understand that WEBrick is more or less just a development web server, I also know from other projects that Mongrel just doesn't cut it. The puppet way of running mongrel also seems to be even more cumbersome than running mongrel with mongrel-cluster. But, in any case, there is no one monitoring your mongrel processes, to see if they would die and then restart them. And I saw lots of mongrels dieing for various reasons already. (None of them were puppet mongrels though, didn't even bother trying that.)
The first result of my effort is a fully working puppetmaster for puppet 0.24.x running as a Passenger app. Technically, it's behaving like a rack application (and my config.ru is using the rack library), so Passenger just auto-discovers it and launches a puppetmaster instance on the first client connect.
All the usual Passenger configuration should apply, including process limits etc.
You may wonder how SSL is handled in this configuration - Apache handles it, just like in a puppetmaster with mongrel setup. This has a few implications: Apache won't start up if the standalone puppetmasterd never started up and created the SSL certificates and CA. Everything else should work just fine.
There's also another catch: Passenger will not start an application as root, but always as the designated application user. Therefore puppetmaster will not create all the usual stuff (== no manifest check). This needs to be done by the standalone puppetmasterd, at least once.Trying it out
- Get puppet 0.24.6-pre from puppet 0.24.x stable branch (at github.com)
- Get my patch from my puppet-dev posting or check the redmine ticket
- Follow the instructions in the puppet wiki
What about 0.25.x?
I'm still working on that. 0.25.x changed the whole server side, so I've got a lot to do here.