file_plugin.rb

class FilePlugin < MetricPlugin
  def initialize(config)
    super
  end

  def process(app, gear, timestamp, fields)
    File.open("/root/gear_metrics.log", 'a') do |f|
      fields.each do |key, value|
        f.puts "#{app}.#{gear}.#{key} #{value} #{timestamp.to_i}"
      end
    end
  end
end

graphite_plugin.rb

require 'socket'

class GraphiteClient
  def carbon
    begin
      @carbon ||= TCPSocket.new('localhost', 2003)
    rescue => e
      @carbon = nil
    end

    @carbon
  end

  def send(data)
    begin
      carbon.puts(data) if carbon
    rescue => e
      @carbon = nil
    end
  end
end

class GraphitePlugin < MetricPlugin
  def initialize(config)
    super
    @client = GraphiteClient.new
  end

  def process(app, gear, timestamp, fields)
    fields.each do |key, value|
      @client.send "#{app}.#{gear}.#{key} #{value} #{timestamp.to_i}"
    end
  end
end

metric_handler.rb

#!/usr/bin/oo-ruby

require 'time'
require 'syslog-logger'
require File.join(File.dirname(__FILE__), 'metric_plugin')

class MetricHandler
  def initialize
    @logger = Logger::Syslog.new('openshift-metrics')
    @logger.level = Logger::DEBUG
    #TODO take in config
    config = {}
    plugin_dir = File.join(File.dirname(__FILE__), 'metric_plugins')
    plugin_files = Dir.glob(File.join(plugin_dir, '*')).find_all { |e| File.file?(e) }

    plugin_files.each do |p|
      begin
        @logger.info "Attempting to load #{p}"
        require p
      rescue LoadError => e
        @logger.info "Error loading #{p}"
      end
    end

    @plugins = MetricPlugin.repository.collect do |plugin|
      begin
        plugin.new(config)
      rescue => e
        @logger.warn "Error loading plugin #{plugin}: #{e.message}"
        nil
      end
    end.to_a.compact

    @logger.error "No valid plugins found in #{plugin_dir}" if @plugins.empty?

    @logger.info "Loaded plugins: #{@plugins.join(', ')}"
  end

  def run
    while line = gets
      begin
        @logger.debug("Received line: #{line}")
        # 2014-02-27T14:50:22.011665-05:00
        timestamp = Time.parse($1) if line =~ /^([^ ]+) /
        @logger.debug "Timestamp = #{timestamp}"
        app = $1 if line =~ /app=([^ ]+)/
        @logger.debug "app = #{app}"
        gear = $1 if line =~ /gear=([^ ]+)/
        @logger.debug "gear = #{gear}"

        # skip if we don't have what we need
        next unless timestamp and app and gear

        index = line.index('type=metric')
        # get all the k=v pairs after type=metric as a hash
        fields = Hash[line[index..-1].split(' ')[1..-1].map {|kv| kv.split('=')}]
        fields.delete('app')
        fields.delete('gear')
        fields.delete('ns')
        @plugins.each do |plugin|
          @logger.debug "Invoking plugin #{plugin}"
          plugin.process(app, gear, timestamp, fields)
          @logger.debug "DONE Invoking plugin #{plugin}"
        end
      end
    end
  end
end

MetricHandler.new.run

metric_plugin.rb

module MetricPluginTemplate
  module ClassMethods
    def repository
      @repository ||= []
    end

    def inherited(klass)
      repository << klass
    end
  end

  def self.included(klass)
    klass.extend ClassMethods
  end
end

class MetricPlugin
  include MetricPluginTemplate

  attr_reader :config

  def initialize(config)
    @config = config
  end

  def process(app, gear, timestamp, fields)
  end
end