gistfile1.pp

$hierayaml = "${settings::confdir}/hiera.yaml"
$hash = loadyaml($hierayaml)

# Displays data with hash key "yaml" present
notice($hash)

# Extract the value of key "yaml"
$yaml = $hash['yaml']

# $yaml is undef?
notice($yaml)

gistfile2.txt

---
:backends:
  - yaml

:yaml:
  :datadir: /etc/puppetlabs/puppet/environments/%{::environment}/hieradata

:hierarchy:
  - "nodes/%{::clientcert}"
  - "environments/%{::environment}"
  - "os/%{::operatingsystem}-%{::operatingsystemrelease}"
  - "os/%{::operatingsystem}-%{::operatingsystemmajrelease}"
  - "os/%{::operatingsystem}"
  - defaults

gistfile3.txt

Notice: Scope(Class[main]): {backends => [yaml], yaml => {datadir => /etc/puppetlabs/puppet/environments/%{::environment}/hieradata}, hierarchy => [nodes/%{::clientcert}, environments/%{::environment}, os/%{::operatingsystem}-%{::operatingsystemrelease}, os/%{::operatingsystem}-%{::operatingsystemmajrelease}, os/%{::operatingsystem}, defaults]}
Notice: Scope(Class[main]):
Notice: Compiled catalog for puppet-tor-b.starfirenetwork.com in environment production in 0.39 seconds
Notice: Finished catalog run in 0.17 seconds