Sinatra app to expose ganglia data

gistfile1.txt

#!/usr/bin/env ruby

##
## This script exposes ganglia data for use by other apps.
## Ask it for a specific host/metric/time triplet, and it
## hands back a json string with the data.
## eg http://localhost/rrdfetch/web12/load_one/3600
## returns the last hour of the load_one metric.
##

require 'rubygems'
require 'sinatra'
require 'find'
require 'json'

get '/rrdfetch/:host/:metric/:time' do
  hostdir = []
  Find.find('/var/lib/ganglia/rrds') do |path|
    hostdir << path if path =~ /#{params['host']}$/
  end
  metric = []
  Find.find(hostdir[0]) do |path|
    metric << path if path =~ /#{params['metric']}.rrd$/
  end
  #sanitize elements
  unless(hostdir[0] =~ /^[a-z0-9\/_.-]+$/)
    halt "hostdir #{hostdir[0]} didn't match regex."
  end
  unless(metric[0] =~ /^[a-z0-9\/_.-]+$/)
    halt "metric #{metric[0]} didn't match regex."
  end
  unless(params['time'] =~ /^\d+$/)
    halt "time #{params['time']} didn't match regex."
  end
  starttime = Time.now - params['time'].to_i
  endtime = Time.now
  puts "rrdtool fetch #{metric[0]} AVERAGE --start #{starttime.strftime('%s')}"
  data = %x{rrdtool fetch #{metric[0]} AVERAGE --start #{starttime.strftime('%s')}}
  mungeddata = []
  data.split("\n").each() do |line|
    (time, val) = line.split(':')
    next if time !~ /\d{8}/
    val = val.to_f
    mungeddata << {:timestamp => Time.at(time.to_i).strftime('%s'), :unit => 'Seconds', :average => val}
  end
  return mungeddata.to_json
  
end