using PQL with Package discovery in Puppet DSL

example.pp

  ##
  # example of how to use puppet package inventory to manage a package on a puppetized host.
  # once puppet package inventory is populated puppet query langauge used puppetdb_query()
  # version comparison is used to manage resource decleration
  # querying a canary or example host can be used to drive patching this way
  ##
  
  
  
  $cowsay_query = "package_inventory{ certname = '$fqdn' and package_name = 'cowsay' }"
  # expected output on test machine
  #[
  #  {
  #    "certname": "master.puppetlabs.vm",
  #    "package_name": "cowsay",
  #    "version": "3.04-4.el7",
  #    "provider": "yum"
  #  }
  #]
  $package = puppetdb_query($cowsay_query)
  #notify {"package info for $package":} #just to prove the output
  
  $version = lookup('package_version') #package_version: '3.04-4.el7'
  #if "$package['version']" !~ $version { 
  if "$package['version']" !~ '3.04-4.el7' { 
    package{'cowsay':
      ensure => '3.04-4.el7', #$version
      noop   => true, #only noop to ensure safe testing
    }
  }