psql_backend.rb

require 'pg'
require 'json'

class Hiera
  module Backend
    class Psql_backend
      def initialize
        Hiera.debug("Hiera PostgreSQL backend starting")
      end

      def lookup(key, scope, order_override, resolution_type)
        answer = nil

        Hiera.debug("Looking up #{key} in PostgreSQL backend")

        Backend.datasources(scope, order_override) do |source|
          connection.exec "SELECT value FROM config WHERE path=$1 AND key=$2", [source, key] do |result|
            # Extra logging that we found the key. This can be outputted
            # multiple times if the resolution type is array or hash but that
            # should be expected as the logging will then tell the user ALL the
            # places where the key is found.
            Hiera.debug("Found #{key} in #{source}")


            entry = result.first
            return nil unless result.first
            new_answer = JSON.load(entry.values_at('value'))


            # for array resolution we just append to the array whatever
            # we find, we then goes onto the next file and keep adding to
            # the array
            #
            # for priority searches we break after the first found data item
            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 = Backend.merge_answer(new_answer,answer)
            else
              answer = new_answer
              break
            end
          end
        end

        return answer
      end

      private

      # Get a config key for this backend
      def self.config(key)
        Config[:psql][key.to_sym]
      end

      def self.connection
        @connection ||= PGconn.open(config :connection)
      end

      def connection
        self.class.connection
      end
    end
  end
end