Wikimedia Labs is a bit like Heroku (for which we have 167 questions), but restricted to Wikimedia-related activities.
People can create/manage instances.
Puppet is used for almost everything, and all configuration (except passwords) is open.
Despite having "Labs" in the name, the platform is used for live production, for instance serving web requests, executing data tasks, etc.
So, if I have a well-researched question about a Puppet deployment to Wikimedia Labs, is it on-topic or off-topic here?