【サンプルコード】aws sdk phpでec2 instance profileを使ってapi gatewayへリクエストする

<?php

require './vendor/autoload.php';

use Aws\Signature\SignatureV4;
use Aws\Credentials\CredentialProvider;
use GuzzleHttp\Psr7\Request;

$method = 'GET';
$region = 'ap-northeast-1';
$stage = 'prod';
$apiName = '/testApi';
$resource = '/test';
$queryAgrs = '?test=1';
$headers = [];
$body = null;
$protocol = '1.1';
$url = 'https://xxxxxx.execute-api.' . $region . '.amazonaws.com/' . $stage . $apiName . $resource . $queryAgr;

$request = new Request($method, $url, $headers, null, $body, $protocol);
$provider = CredentialProvider::instanceProfile();
$credentials = $provider()->wait();
$sigv4 = new SignatureV4('execute-api', $region);
$ret = $sigv4->signRequest($request, $credentials);