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 16 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
Finds the path to a datafile based on the Backend#datadir and extension
If the file is not found nil is returned
# File lib/hiera/backend.rb, line 37 def datafile(backend, scope, source, extension) file = File.join([datadir(backend, scope), "#{source}.#{extension}"]) unless File.exist?(file) Hiera.debug("Cannot find datafile #{file}, skipping") return nil end return file end
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 60 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
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 167 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
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 143 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
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 100 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 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 92 def parse_string(data, scope, extra_data={}) Hiera::Interpolate.interpolate(data, Hiera::RecursiveGuard.new, scope, extra_data) end
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