Convert hiera3 to hiera5

hiera.yaml

---
:backends:
  - yaml
  - eyaml
  - mongodb
  - xml

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

:eyaml:
  :datadir: "/etc/puppetlabs/code/environments/%{environment}/hieradata"
  :pkcs7_private_key: /path/to/private_key.pkcs7.pem
  :pkcs7_public_key:  /path/to/public_key.pkcs7.pem

:mongodb:
  :connections:
    :dbname: hdata
    :collection: config
    :host: localhost

:xml:
  :datadir: /some/other/dir

:hierarchy:
  - "%{trusted.certname}"
  - "common"

hiera5er.rb

#!/opt/puppetlabs/puppet/bin/ruby
require 'yaml'

class HieraFiver

  def initialize(config_file)
    @backends_data_hash  = ['yaml', 'json']
    @backends_lookup_key = ['eyaml']

    @config5 = { 'version' => 5, 'hierarchy' => [], }
    @config3 = YAML.load_file(config_file)
  end

  # Use accessors in order to specify more backends under each category
  attr_accessor :backends_data_hash, :backends_lookup_key

  def print5
    puts fix_quotes(@config5.to_yaml)
  end

  def parse_config3
    @config3[:backends].each do |backend|
      if @backends_data_hash.include?(backend)
        lookupk = 'data_hash'
        lookupv = "#{backend}_data"
      elsif @backends_lookup_key.include?(backend)
        lookupk = 'lookup_key'
        lookupv = "#{backend}_lookup_key"
      else
        lookupk = 'hiera3_backend'
        lookupv = backend
      end
      level = {
        'name'    => "#{backend.capitalize} backend",
        lookupk   => lookupv,
        'paths'   => @config3[:hierarchy].map { |p| interpolate(p) },
      }
      level['datadir'] = @config3[backend.to_sym][:datadir] if @config3[backend.to_sym][:datadir]
      level['options'] = options_hash(backend) if has_options?(backend)
      @config5['hierarchy'] << level
    end
  end

  private

  def options_hash(backend)
    options = Hash.new
    @config3[backend.to_sym].each do |k,v|
      options[k.to_s] = no_symbols(v) unless k == :datadir
    end
    options
  end

  def no_symbols(input)
    if input.is_a?(Hash)
      Hash[input.map{ |k, v| [k.to_s, v] }] if input.is_a?(Hash)
    else
      input
    end
  end

  def has_options?(backend)
    @config3[backend.to_sym].select { |k,v| k != :datadir }.length > 0
  end

  def interpolate(path)
    if path.include?('%')
      "'#{path}'"
    else
      "\"#{path}\""
    end
  end

  def fix_quotes(input)
    # YAML does quotes automatically, so unable to easily
    # leave a double-quoted interpolation string behind.
    fixed = input.gsub(/^(\s+)\- "'/, '\1- "')
    fixed = fixed.gsub(/^(\s+)\- '"/, '\1- \'')
    fixed = fixed.gsub(/'"$/, '"')
    fixed = fixed.gsub(/"'$/, '\'')
    fixed
  end
end

config_file = ARGV[0] || '/etc/puppetlabs/puppet/hiera.yaml'
conversion  = HieraFiver.new(config_file)
# Specify more lookup_key backends
# conversion.backends_lookup_key=(['eyaml','someotherlookup'])
conversion.parse_config3
conversion.print5

shell.out

[root@puppet2017 ~]# ./hiera5er.rb hiera.yaml
---
version: 5
hierarchy:
- name: Yaml backend
  data_hash: yaml_data
  paths:
  - "%{trusted.certname}"
  - 'common'
  datadir: "/etc/puppetlabs/code/environments/%{environment}/hieradata"
- name: Eyaml backend
  lookup_key: eyaml_lookup_key
  paths:
  - "%{trusted.certname}"
  - 'common'
  datadir: "/etc/puppetlabs/code/environments/%{environment}/hieradata"
  options:
    pkcs7_private_key: "/path/to/private_key.pkcs7.pem"
    pkcs7_public_key: "/path/to/public_key.pkcs7.pem"
- name: Mongodb backend
  hiera3_backend: mongodb
  paths:
  - "%{trusted.certname}"
  - 'common'
  options:
    connections:
      dbname: hdata
      collection: config
      host: localhost
- name: Xml backend
  hiera3_backend: xml
  paths:
  - "%{trusted.certname}"
  - 'common'
  datadir: "/some/other/dir"