Day 16 in the #vDM30in30 I actually wrote a Stack Overflow answer to this, but I thought I’d formalise and update it a bit.
How do the GUI’s work? So, most Puppet GUI’s and Dashboards use reporting from PuppetDB, so as long as you have PuppetDB in your infra they will work, regardless of your Puppet version. It simply takes reports from PuppetDB and performs queries again PuppetDB for searches about information.