aws-elb-check.php

<?php

  define("AWS_KEY","YOUR KEY");
  define("AWS_SECRET","YOUR SECRET KEY");
  define("AWS_REGION","REGION OF THE LOAD BALANCER");
  define("ELB_NAME","YOUR ELB NAME");
  define("INSTANCE_ID","CURRENT INSTANCE ID - TO BE EXLUCDED FROM THE TEST");
  
  //no cache headers 
  header("Expires: 0");
  header("Cache-Control: no-store, no-cache, must-revalidate");
  header("Pragma: no-cache");
  
  require 'AWSSDKforPHP/aws.phar';
  
  use Aws\ElasticLoadBalancing\ElasticLoadBalancingClient;
  
  $client = ElasticLoadBalancingClient::factory(array(
              'key'    => AWS_KEY,
              'secret' => AWS_SECRET,
              'region' => AWS_REGION
          ));
  

  print "Checking =>".ELB_NAME."(".AWS_REGION.")<br>";
  
  foreach($result["InstanceStates"] as $instance){
  
          print $instance["InstanceId"]."-".$instance["State"]."<br>";
          if($instance["InstanceId"] != INSTANCE_ID && $instance["State"] == "InService"){
                  header("HTTP/1.1 500 Internal Server Error");
                  die("At least one server is UP");
          }
  }
  
  die("Servers are down - show down error");

?>