Puppet Function: simplib::filtered

Defined in:
lib/puppet/functions/simplib/filtered.rb
Function type:
Ruby 4.x API

Overview

Hiera v5 backend that takes a list of allowed hiera key names, and only returns results from the underlying backend function that match those keys.

This allows hiera data to be delegated to end users in a multi-tenant environment without allowing them the ability to override every hiera data point (and potentially break systems)

Examples:

Enabling the Backend

---
version: 5 # Specific version of hiera we are using, required for v4 and v5
defaults:  # Used for any hierarchy level that omits these keys.
  datadir: "data"         # This path is relative to hiera.yaml's directory.
  data_hash: "yaml_data"  # Use the built-in YAML backend.
hierarchy: # Each hierarchy consists of multiple levels
  - name: "OSFamily"
    path: "osfamily/%{facts.os.family}.yaml"
  - name: "datamodules"
    data_hash: simplib::filtered
    datadir: "delegated-data"
    paths:
      - "%{facts.sitename}/osfamily/%{facts.os.family}.yaml"
      - "%{facts.sitename}/os/%{facts.os.name}.yaml"
      - "%{facts.sitename}/host/%{facts.networking.fqdn}.yaml"
      - "%{facts.sitename}/common.yaml"
    options:
      function: yaml_data
    filter:
      - profiles::ntp::servers
      - profiles::.*
  - name: "Common"
    path: "common.yaml"

Signatures:

  • simplib::filtered(Hash $options, Puppet::LookupContext $context) ⇒ Hash

    Parameters:

    • options (Hash)
    • context (Puppet::LookupContext)

    Returns:

    • (Hash)
  • simplib::filtered(String $key, Hash $options, Puppet::LookupContext $context) ⇒ Hash

    Parameters:

    • key (String)
    • options (Hash)
    • context (Puppet::LookupContext)

    Returns:

    • (Hash) 


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# File 'lib/puppet/functions/simplib/filtered.rb', line 32

Puppet::Functions.create_function(:'simplib::filtered') do
  # @param options
  # @param context
  #
  # @return [Hash]
  dispatch :filtered do
    param 'Hash', :options
    param 'Puppet::LookupContext', :context
  end

  # @param key
  # @param options
  # @param context
  #
  # @return [Hash]
  dispatch :filtered_lookup_key do
    param 'String', :key
    param 'Hash', :options
    param 'Puppet::LookupContext', :context
  end

  def filtered(options, context)
    backend = call_function(options['function'], options, context)
    data = {}
    backend.each do |key, value|
      check_filter(key, options['filter']) do |nkey|
        data[nkey] = value
      end
    end
    data
  end

  def filtered_lookup_key(key, options, context)
    retval = nil
    check_filter(key, options['filter']) do |k|
      retval = call_function(options['function'], k, options, context)
      if retval.nil?
        context.not_found
      end
    end
    if retval.nil?
      context.not_found
    else
      retval
    end
  end

  def check_filter(key, filter)
    filtered = false
    filter.each do |keyname|
      if key&.match?(Regexp.new(keyname))
        filtered = true
      end
    end
    return unless filtered == false
    yield key
  end
end