Module: Hiera::Backend

Defined in:
lib/hiera/backend.rb,
lib/hiera/backend/json_backend.rb,
lib/hiera/backend/yaml_backend.rb

Defined Under Namespace

Classes: Json_backend, Yaml_backend

Class Method Summary collapse

Class Method Details

.clear! ⇒ Object 



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# File 'lib/hiera/backend.rb', line 233

def clear!
  @backends = {}
end

.datadir(backend, scope) ⇒ Object

Data lives in /var/lib/hiera by default. If a backend supplies a datadir in the config it will be used and subject to variable expansion based on scope



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# File 'lib/hiera/backend.rb', line 15

def datadir(backend, scope)
  backend = backend.to_sym

  if Config[backend] && Config[backend][:datadir]
    dir = Config[backend][:datadir]
  else
    dir = Hiera::Util.var_dir
  end

  if !dir.is_a?(String)
    raise(Hiera::InvalidConfigurationError,
          "datadir for #{backend} cannot be an array")
  end

  parse_string(dir, scope)
end

.datafile(backend, scope, source, extension) ⇒ Object

Finds the path to a datafile based on the Backend#datadir and extension

If the file is not found nil is returned



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# File 'lib/hiera/backend.rb', line 36

def datafile(backend, scope, source, extension)
  datafile_in(datadir(backend, scope), source, extension)
end

.datafile_in(datadir, source, extension) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/hiera/backend.rb', line 41

def datafile_in(datadir, source, extension)
  file = File.join(datadir, "#{source}.#{extension}")

  if File.exist?(file)
    file
  else
    Hiera.debug("Cannot find datafile #{file}, skipping")
    nil
  end
end

.datasourcefiles(backend, scope, extension, override = nil, hierarchy = nil) {|String, String| ... } ⇒ Object

Constructs a list of data files to search

If you give it a specific hierarchy it will just use that else it will use the global configured one, failing that it will just look in the ‘common’ data source.

An override can be supplied that will be pre-pended to the hierarchy.

The source names will be subject to variable expansion based on scope

Only files that exist will be returned. If the file is missing, then the block will not receive the file.

Yields:

  • (String, String) —

    the source string and the name of the resulting file



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# File 'lib/hiera/backend.rb', line 97

def datasourcefiles(backend, scope, extension, override=nil, hierarchy=nil)
  datadir = Backend.datadir(backend, scope)
  Backend.datasources(scope, override, hierarchy) do |source|
    Hiera.debug("Looking for data source #{source}")
    file = datafile_in(datadir, source, extension)

    if file
      yield source, file
    end
  end
end

.datasources(scope, override = nil, hierarchy = nil) ⇒ Object

Constructs a list of data sources to search

If you give it a specific hierarchy it will just use that else it will use the global configured one, failing that it will just look in the ‘common’ data source.

An override can be supplied that will be pre-pended to the hierarchy.

The source names will be subject to variable expansion based on scope



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# File 'lib/hiera/backend.rb', line 63

def datasources(scope, override=nil, hierarchy=nil)
  if hierarchy
    hierarchy = [hierarchy]
  elsif Config.include?(:hierarchy)
    hierarchy = [Config[:hierarchy]].flatten
  else
    hierarchy = ["common"]
  end

  hierarchy.insert(0, override) if override

  hierarchy.flatten.map do |source|
    source = parse_string(source, scope)
    yield(source) unless source == "" or source =~ /(^\/|\/\/|\/$)/
  end
end

.lookup(key, default, scope, order_override, resolution_type) ⇒ Object

Calls out to all configured backends in the order they were specified. The first one to answer will win.

This lets you declare multiple backends, a possible use case might be in Puppet where a Puppet module declares default data using in-module data while users can override using JSON/YAML etc. By layering the backends and putting the Puppet one last you can override module author data easily.

Backend instances are cached so if you need to connect to any databases then do so in your constructor, future calls to your backend will not create new instances



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# File 'lib/hiera/backend.rb', line 199

def lookup(key, default, scope, order_override, resolution_type)
  @backends ||= {}
  answer = nil

  Config[:backends].each do |backend|
    if constants.include?("#{backend.capitalize}_backend") || constants.include?("#{backend.capitalize}_backend".to_sym)
      @backends[backend] ||= Backend.const_get("#{backend.capitalize}_backend").new
      new_answer = @backends[backend].lookup(key, scope, order_override, resolution_type)

      if not new_answer.nil?
        case resolution_type
        when :array
          raise Exception, "Hiera type mismatch: expected Array and got #{new_answer.class}" unless new_answer.kind_of? Array or new_answer.kind_of? String
          answer ||= []
          answer << new_answer
        when :hash
          raise Exception, "Hiera type mismatch: expected Hash and got #{new_answer.class}" unless new_answer.kind_of? Hash
          answer ||= {}
          answer = merge_answer(new_answer,answer)
        else
          answer = new_answer
          break
        end
      end
    end
  end

  answer = resolve_answer(answer, resolution_type) unless answer.nil?
  answer = parse_string(default, scope) if answer.nil? and default.is_a?(String)

  return default if answer.nil?
  return answer
end

.merge_answer(left, right) ⇒ Object

Merges two hashes answers with the configured merge behavior.

:merge_behavior: {:native|:deep|:deeper}

Deep merge options use the Hash utility function provided by [deep_merge](github.com/peritor/deep_merge)

:native => Native Hash.merge
:deep   => Use Hash.deep_merge
:deeper => Use Hash.deep_merge!



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# File 'lib/hiera/backend.rb', line 175

def merge_answer(left,right)
  case Config[:merge_behavior]
  when :deeper,'deeper'
    left.deep_merge!(right)
  when :deep,'deep'
    left.deep_merge(right)
  else # Native and undefined
    left.merge(right)
  end
end

.parse_answer(data, scope, extra_data = {}) ⇒ Object

Parses a answer received from data files

Ultimately it just pass the data through parse_string but it makes some effort to handle arrays of strings as well



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# File 'lib/hiera/backend.rb', line 132

def parse_answer(data, scope, extra_data={})
  if data.is_a?(Numeric) or data.is_a?(TrueClass) or data.is_a?(FalseClass)
    return data
  elsif data.is_a?(String)
    return parse_string(data, scope, extra_data)
  elsif data.is_a?(Hash)
    answer = {}
    data.each_pair do |key, val|
      interpolated_key = parse_string(key, scope, extra_data)
      answer[interpolated_key] = parse_answer(val, scope, extra_data)
    end

    return answer
  elsif data.is_a?(Array)
    answer = []
    data.each do |item|
      answer << parse_answer(item, scope, extra_data)
    end

    return answer
  end
end

.parse_string(data, scope, extra_data = {}) ⇒ String

Parse a string like '%{foo}' against a supplied scope and additional scope. If either scope or extra_scope includes the variable ‘foo’, then it will be replaced else an empty string will be placed.

If both scope and extra_data has “foo”, then the value in scope will be used.

Parameters:

  • data (String) —

    The string to perform substitutions on. This will not be modified, instead a new string will be returned.

  • scope (#[]) —

    The primary source of data for substitutions.

  • extra_data (#[]) (defaults to: {}) —

    The secondary source of data for substitutions.

Returns:

  • (String) —

    A copy of the data with all instances of %{...} replaced.



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# File 'lib/hiera/backend.rb', line 124

def parse_string(data, scope, extra_data={})
  Hiera::Interpolate.interpolate(data, scope, extra_data)
end

.resolve_answer(answer, resolution_type) ⇒ Object 



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# File 'lib/hiera/backend.rb', line 155

def resolve_answer(answer, resolution_type)
  case resolution_type
  when :array
    [answer].flatten.uniq.compact
  when :hash
    answer # Hash structure should be preserved
  else
    answer
  end
end