apache_vh_errors

#!/usr/bin/php
<?php
/*
 Copyright (c) 2009 Ben Lumley (@benlumley)

 Permission is hereby granted, free of charge, to any person
 obtaining a copy of this software and associated documentation
 files (the "Software"), to deal in the Software without
 restriction, including without limitation the rights to use,
 copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the
 Software is furnished to do so, subject to the following
 conditions:

 The above copyright notice and this permission notice shall be
 included in all copies or substantial portions of the Software.

 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 OTHER DEALINGS IN THE SOFTWARE.
*/

// path where the apache logs are to be found
define('LOG_PATH', "/var/log/apache2/");

// number of lines to start with in the access log - improving this may reduce the number of times it checks
define('ACCESS_LINES', 1000);

// number of lines to start with in the error log
define('ERROR_LINES', 100);

// $excludes is an array of urls to exclude. use it to exclude testing sites.
$excludes = array();
$excludes[]="|^.dev.*$|i";

// $includes is a list of sites that should be included, regardless of the above regex.
$includes = array();
$includes[] = "development.com";

exec(sprintf("find %s -iname *_access.log", LOG_PATH), $files);

foreach ($files as $key=>$file) {
	 foreach ($includes as $include) {
		 if (strpos($file, $include)) {
		   continue 2;
	   }
	 }
   foreach ($excludes as $exclude) {
      if (preg_match($exclude, $file)) {
         unset($files[$key]);
         continue 2;
      }
   }
}

if (isset($argv[1]) && $argv[1]=='config') {
   foreach ($files as $file) {
      $sitename = sitename($file);
      #echo hashname($file) . "_error.label $sitename (err/sec)\n";
      echo hashname($file) . "_error_req.label $sitename\n";
      echo hashname($file) . "_error_req.warning 5\n";
      echo hashname($file) . "_error_req.critical 10\n";
   }
   echo "graph_category apache\n";
   echo "graph_title Apache Errors By Vhost\n";
   echo "graph_vlabel Errors per request\n";
   echo "graph_info This graph shows errors per request by virtual host\n";
} else {
   foreach ($files as $file) {
      $access_rate = calculate_rate($file, ACCESS_LINES);
      $error_rate = calculate_rate(str_replace('access', 'error', $file), ERROR_LINES);
#     echo hashname($file) . "_error.value " . $error_rate . "\n";
      if ($error_rate == 0 || $access_rate == 0) {
         $err_req = 0;
      } else {
         $err_req = round($error_rate/$access_rate, 4);
      }
      echo hashname($file) . "_error_req.value $err_req\n";
   }
}

function calculate_rate($file, $num_lines) {
  $ago = get_time($file, $num_lines);
  $increment = floor($num_lines/2);
  $its = 0;
  $opp = false;
  while ($ago < 270 || $ago > 330) {
    if ($ago < 270) {
      if ($opp == "sub") {
        $increment = floor($increment/2);
      }
      $num_lines = $num_lines + $increment;
      $opp = "add";
    } elseif ($ago > 330) {
      if ($opp == "add") {
        $increment = floor($increment/2);
      }
      $num_lines = max(1, $num_lines - $increment);
      $opp = "sub";
    }
    $ago = get_time($file, $num_lines);
    if ($num_lines == 1 && $ago > 330) {
      return 0.000;
    }
    $its++;
    if ($its == 10) {
      break;
    }
  }
  return round($num_lines/$ago, 4);
}

function get_time($file, $num_lines) {
  $string = exec(sprintf("tail -n %s %s 2>/dev/null | head -n 1", $num_lines, $file));
  $checkstring =  exec(sprintf("head -n 1 %s 2>/dev/null", $file));
  
  // if we get to log start, use size of log as num_lines, to minimise skew.
  $checkstring =  exec(sprintf("head -n 1 %s 2>/dev/null", $file));
  if ($checkstring == $string) {
    $seen_lines =  exec(sprintf("wc -l %s 2>/dev/null", $file));
    if (file_exists($file . ".1")) {
      $string = exec(sprintf("tail -n %s %s.1 2>/dev/null | head -n 1", ($num_lines - $seen_lines), $file));
    } else {
      $num_lines = $seen_lines;
    }
  }
  
  preg_match('|^([^\[]*)?\[([^]]+)\].*|', $string, $matches);
  if (!isset($matches[2])) {
    $time = time();
  } else {
    $time = strtotime($matches[2]);
  }
  $ago = time() - $time;
  return $ago;
}

function hashname($file) {
   return 'f_' . preg_replace('|[^a-z0-9]|i', '', sitename($file));
}

function sitename($file) {
   list($sitename)=explode("_", basename($file));
   return $sitename;
}