AWS SDK for PHPで特定のELBのEC2 instanceを取得

capistranoで特定のELBに紐づくEC2 instanceに対してスクリプトを実行させたかったので、書きました。

参考URL（http://docs.aws.amazon.com/aws-sdk-php/v2/api/index.html）

まず、aws-sdk-phpは最新の3系を使用

composer.json

{
    "require": {
      "aws/aws-sdk-php": "3.3.3"
  }
}

util_ec2.php

<?php

require_once('vendor/autoload.php');

use Aws\ElasticLoadBalancing\ElasticLoadBalancingClient;
use Aws\Ec2\Ec2Client;

class Util_Ec2 {

  private $elb_client = null;
  private $ec2_client = null;

  function __construct() {
    date_default_timezone_set("Asia/Tokyo");
    $config = [
      'version' => 'latest',
      'region' => region,
      'credentials' => [
        'key'    => access_key,
        'secret' => secret_key,
      ]
    ];
    $this->elb_client = new ElasticLoadBalancingClient($config);
    $this->ec2_client = new Ec2Client($config);
  }

  public function get_instances() {
    $elb_name = elb name;
    $instance_ids = [];
    $instances = $this->elb_client->describeInstanceHealth([
      'LoadBalancerName'=> $elb_name
    ]);
    foreach ($instances['InstanceStates'] as $instanceState) {
      $instance_ids[] = $instanceState['InstanceId'];
    }    
    $instances = $this->ec2_client->describeInstances([
      'InstanceIds' => $instance_ids
    ]);
    return $instances;
  }

}

$util_ec2 = new Util_Ec2();
$instances = $util_ec2->get_instances();