I've been trying to put some thought into what our strategy is going to be for maintaining backward-compatibility with older versions of PuppetDB.  Two of these settings are harmless on that front--though perhaps misleading.  However, for the node-ttl setting we are not providing a way to define the older node-ttl-days setting here, which means we're exposing a setting that was available in 1.0 but not the means to actually set it.

I worry that the module is going to get really hairy if we try to maintain backward compatibility too far into the past, so I think my current inclination is to simply start documenting (very prominently--at the top of the main README or similar) that certain versions of the module are only compatible with certain versions of puppetdb.  If you want to use an older version of puppetdb then you use an older version of the module.

Thoughts?  @kbarber ?