module Hiera::Backend

Public Instance Methods

clear!() click to toggle source
# File lib/hiera/backend.rb, line 233
def clear!
  @backends = {}
end
datadir(backend, scope) click to toggle source

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

# 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) click to toggle source

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

If the file is not found nil is returned

# 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) click to toggle source

@api private

# 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) { |source, file| ... } click to toggle source

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.

@yield [String, String] the source string and the name of the resulting file @api public

# 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) { |source| ... } click to toggle source

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

# 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) click to toggle source

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

# 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) click to toggle source

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!
# 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={}) click to toggle source

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

# 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={}) click to toggle source

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.

@param data [String] The string to perform substitutions on.

This will not be modified, instead a new string will be returned.

@param scope [#[]] The primary source of data for substitutions. @param extra_data [#[]] The secondary source of data for substitutions. @return [String] A copy of the data with all instances of %{...} replaced.

@api public

# 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) click to toggle source
# 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