graphserver.rb

#!/usr/bin/ruby

require 'rubygems'
require 'json'
require 'sinatra'
require 'sparklines'
require 'ftools';

@@rrd_path       = "/var/lib/ganglia/rrds/"

### due to the new ganglia setup (see FB 5), the server is now known
### by it's FQDN, and not localhost, so we have to change the path
### on the file system to match --jos
@@liftium_path   = "#{@@rrd_path}/Liftium/liftium-s1/"

# 2x2 pixel gif
@@fallback_image = File.expand_path( File.dirname( $0 ) + '/white.gif' );

def send_rrd_graph(rrd_opts) 
  temp_file =  Tempfile.new('rrd-image')
  rrd_opts.unshift temp_file.path

  # on success, send the graph
  if system "rrdtool graph #{rrd_opts.join(' ')}"
    send_file temp_file.path, 
                :type        => 'image/png',
			    :disposition => nil
    temp_file.close
  # otherwise, send a fallback image  
  else 
    # XXX don't know how to capture STDERR from a syscall :(
    send_fallback_image "System call failed: " + $?.to_s
  end 
end

def send_fallback_image( reason )

    ### record why we're sending this image
    warn "[ERROR] Sending fallback image because: #{reason}"

    ### record why we're sending this error
    @response[ "X-GraphError" ] = "#{reason}"   

    send_file @@fallback_image,
                :type           => 'image/gif',
                :disposition    => nil

end

def get_rrd_array(range,net,tag)
  results = []
  rrd_opts = []
  rrd_opts << "--start=-#{params[:range]}"

  rrd_opts << "-m 75"
  ['loads','attempts'].each do |stat|
    rrd_opts << "DEF:#{stat}=#{@@liftium_path}/liftium_#{net}_#{tag}_#{stat}.rrd:sum:AVERAGE"
  end
  rrd_opts << "CDEF:fill=loads,attempts,/,100,*"
  rrd_opts << "XPORT:fill"

  xml = `rrdtool xport #{rrd_opts.join(' ')}`
  data = xml.scan(/<v>(.*)<\/v>/)
  data.each do |item|
    if item[0].to_s == "NaN"
      results << 0
    else
      # Convert rrds sci notation to decimal
      value = "%4.2f" % item[0]
      results << value.to_i
    end
  end
  return results
end

get '/chart' do
  rrd_opts = []
  colors = [ "00FF00C0", "FF0000C0", "0000FFC0" ]
  net = params[:net]
  tag = params[:tag]

  rrd_opts << "--start=-#{params[:range]}"
  rrd_opts << "--title=\"#{params[:title]}\""
  rrd_opts << "--vertical-label=requests"
  rrd_opts << "--height=#{params[:height]}"
  rrd_opts << "--width=#{params[:width]}"
  rrd_opts << "--slope-mode"
  rrd_opts << "--lower-limit=0"

  ['attempts','rejects','loads'].each do |stat|
    rrd_opts << "DEF:#{stat}=#{@@liftium_path}/liftium_#{net}_#{tag}_#{stat}.rrd:sum:AVERAGE"
    rrd_opts << "AREA:#{stat}\##{colors.shift}:#{stat}"
  end
  rrd_opts << "VDEF:attempts_max=attempts,MAXIMUM"
  rrd_opts << "CDEF:fill_rate=loads,attempts,/,attempts_max,*"
  rrd_opts << "LINE:fill_rate#000000:fill_rate"

  send_rrd_graph(rrd_opts)
end 

get '/misc' do
  rrd_opts = []
  stat = params[:stat]

  rrd_opts << "--start=\"-#{params[:range]}\""
  rrd_opts << "--title=\"#{params[:title]}\""
  rrd_opts << "--height=#{params[:height]}"
  rrd_opts << "--width=#{params[:width]}"
  rrd_opts << "--slope-mode"

  rrd_opts << "DEF:#{stat}=#{@@liftium_path}/liftium_#{stat}.rrd:sum:AVERAGE"
  rrd_opts << "AREA:#{stat}\#000000CC:#{stat}"

  send_rrd_graph(rrd_opts)
end 

get '/sparkline' do
  send_fallback_image "Manually disabled for perf"
  range = params[:range]
  net = params[:net]
  tag = params[:tag]
  
  results = get_rrd_array(range,net,tag)
  begin 
      image = Sparklines.plot( results, 
            :type           => 'area',
            :min            => 0,
            :max            => 100,
            :step           => 3,
            :upper          => 0,
            :above_color    => "#0098E0",
            :height         => params[:height] )

      content_type 'image/png'
      image	
  rescue Exception => e    
    send_fallback_image e.to_s
  end
  
  return image
  
end

get '/json_spark' do
  range = params[:range]
  net = params[:net]
  tag = params[:tag]

  results = get_rrd_array(range,net,tag)
  return results.to_json

end