Simple PHP Class to send data to AWS Eventbridge

AmazonEventbridge.php

<?php

/*
POST / HTTP/1.1
Host: events.<region>.<domain>
x-amz-Date: <Date>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=content-type;date;host;user-agent;x-amz-date;x-amz-target;x-amzn-requestid, Signature=<Signature>
User-Agent: <UserAgentString>
Content-Type: application/x-amz-json-1.1
Content-Length: <PayloadSizeBytes>
Connection: Keep-Alive 
X-Amz-Target: AWSEvents.PutEvents

{
   "Entries":[
      {
         "Source":"com.mycompany.myapp",
         "Detail":"{ \"key1\": \"value1\", \"key2\": \"value2\" }",
         "Resources":[
            "resource1",
            "resource2"
         ],
         "DetailType":"myDetailType"
      },
      {
         "Source":"com.mycompany.myapp",
         "Detail":"{ \"key1\": \"value3\", \"key2\": \"value4\" }",
         "Resources":[
            "resource1",
            "resource2"
         ],
         "DetailType":"myDetailType"
      }
   ]
}
*/

class AmazonEventbridge
{

    static  $utc_tz;

    /** @var string $access_key */
    private $ACCESS_KEY;
    /** @var string $secret_key */
    private $SECRET_KEY;
    private $REGION = 'eu-west-1';

    public function __construct($access_key, $secret_key, $region = 'eu-west-1')
    {
        $this->ACCESS_KEY = $access_key;
        $this->SECRET_KEY = $secret_key;

        if (empty($this->ACCESS_KEY) || empty($this->SECRET_KEY)) {
            throw new InvalidArgumentException('Must define Amazon access key and secret key');
        }

        $this->REGION = $region;
    }

    // Minimum number of 1 item. Maximum number of 10 items.
    function eventbridge($eventBus, $source, $detailType, $entries)
    {

        if (!is_array($entries)) throw new Exception("Argument entries must be an array");
        if (count($entries) == 0 || count($entries) > 10) throw new Exception("Argument must minimum of 1 and maximum 10 entries");

        if (!self::$utc_tz)
            self::$utc_tz = new \DateTimeZone('UTC');

        $APIVERSION = '20131202';
        $datestamp  = new \DateTime("now", self::$utc_tz);
        $longdate   = $datestamp->format("Ymd\\THis\\Z");
        $shortdate  = $datestamp->format("Ymd");


        $out = array();
        foreach ($entries as $entry) {
            print_r($entry);
            $arr = array(
                "EventBusName" => $eventBus,
                "Source" => $source, // The source of the event.
                "Detail" => json_encode($entry), // A valid JSON string
                "DetailType" => $detailType, // Free-form string used to decide what fields to expect in the event detail,
                // "TraceHeader" => 
            );
            array_push($out, $arr);
        }

        $payload = json_encode(array("Entries" => $out));

        // establish the signing key
        {
            $ksecret    = 'AWS4' . $this->SECRET_KEY;
            $kdate      = hash_hmac('sha256', $shortdate, $ksecret, true);
            $kregion    = hash_hmac('sha256', $this->REGION, $kdate, true);
            $kservice   = hash_hmac('sha256', 'events', $kregion, true);
            $ksigning   = hash_hmac('sha256', 'aws4_request', $kservice, true);
        }

        // command parameters
        $params     = array(
            'host'          => 'events.' . $this->REGION . '.amazonaws.com',
            'content-type'  => 'application/x-amz-json-1.1',
            'x-amz-date'    => $longdate,
            'x-amz-target'  => 'AWSEvents.PutEvents',
            'content-length' => strlen($payload),
            'user-agent'    => 'PHPEventbridgeLib',
            'connection'    => 'keep-alive',
        );

        $canonical_request  = $this->createCanonicalRequest($params, $payload);
        $signed_request     = hash('sha256', $canonical_request);
        $sign_string        = "AWS4-HMAC-SHA256\n{$longdate}\n$shortdate/" . $this->REGION . "/events/aws4_request\n" . $signed_request;
        $signature          = hash_hmac('sha256', $sign_string, $ksigning);

        $params['authorization'] = "AWS4-HMAC-SHA256 Credential=" . $this->ACCESS_KEY . "/$shortdate/" . $this->REGION . "/events/aws4_request, " .
            "SignedHeaders=" . implode(";", array_keys($params))  . ", " .
            "Signature=$signature";


        /*
         * Execute Crafted Request
         */

        $url    = "https://events." . $this->REGION . ".amazonaws.com";
        $ch     = curl_init();

        $curl_headers = array();
        foreach ($params as $p => $k)
            $curl_headers[] = $p . ": " . $k;

        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $payload);
        curl_setopt($ch, CURLOPT_HTTPHEADER, $curl_headers);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_TCP_NODELAY, true);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

        // debug opts
        {
            curl_setopt($ch, CURLOPT_VERBOSE, true);
            $verbose = fopen('php://temp', 'rw+');
            curl_setopt($ch, CURLOPT_STDERR, $verbose);
            $result = curl_exec($ch); // raw result
            rewind($verbose);
            $verboseLog = stream_get_contents($verbose);
        }
        $rescode = curl_getinfo($ch, CURLINFO_HTTP_CODE);

        if ($rescode == '200') {
            return true;
        } else {
            throw new EventbridgeException("Invalid server response " . $rescode .  $result);
        }
    }

    private function createCanonicalRequest(array $params, $payload)
    {
        $canonical_request      = array();
        $canonical_request[]    = 'POST';
        $canonical_request[]    = '/';
        $canonical_request[]    = '';

        $can_headers            = array(
            'host' => 'events.' . $this->REGION . '.amazonaws.com'
        );

        foreach ($params as $k => $v)
            $can_headers[strtolower($k)] = trim($v);

        uksort($can_headers, 'strcmp');

        foreach ($can_headers as $k => $v)
            $canonical_request[] = $k . ':' . $v;

        $canonical_request[] = '';
        $canonical_request[] = implode(';', array_keys($can_headers));
        $canonical_request[] = hash('sha256', $payload);

        $canonical_request = implode("\n", $canonical_request);

        return $canonical_request;
    }
}

class EventbridgeException extends Exception
{
}

// $eb = new AmazonEventbridge("xxx", "xxx");
// $eb->eventbridge("busname", "com.eventsource", "Some testing", array(array("action" => "test", "somethng" => "else")));