hiera defines musings

gistfile1.txt

define mymodule::party( $param1 , $param2
) {
}

With Hiera I can do 

define mymodule::party( $param1 = hiera('param1','somedefault1') , $param2 = hiera('param2','somedefault2')
) {
}

But I'd like to have the default come from my data.pp/params.pp file per module

Would the hiera backend :puppet take care of this?

sample.pp

define logstash::agent(                                                                                                   
  $osUser = undef ,                                                                                                       
  $version = undef ,                                                                                                      
  $installDir = undef ,                                                                                                   
  $downloadUrl = undef ,                                                                                                  
  $javaHome = undef ,                                                                                                     
  $javaMx = undef ,                                                                                                       
  $config = undef                                                                                                         
) {                                                                                                                       
                                                                                                                          
  # Load defaults from params (and possibly hiera)                                                                        
  include logstash::data                                                                                                  
                                                                                                                          
  # some day we'll replace it with                                                                                        
  # defaultify('real_','data',['osUser','version','...'])                                                                 
  # Alternative1: use data.pp with puppet data in hiera - makes the module dependent on hiera config                      
  # Alternative2: use $osUser = hiera(... in vars, means we can't put module config in a central place                    
                                                                                                                          
  if $osUser == undef { $real_osUser = $logstash::data::osUser } else { $real_osUser = $osUser }                          
  if $version == undef { $real_version = $logstash::data::version } else { $real_javaMx = $javaMx }                       
  if $installDir == undef { $real_installDir = $logstash::data::installDir } else { $real_installDir = $installDir }      
  if $downloadUrl == undef { $real_downloadUrl = $logstash::data::downloadUrl } else { $real_downloadUrl = $downloadUrl }