index.php

<?php

use Armakuni\Demo\PhpInserter\ConfigFactory;
use Armakuni\Demo\PhpInserter\StackdriverExporterFactory;
use Armakuni\Demo\PhpInserter\TraceService;
use OpenCensus\Trace\Tracer;

require __DIR__ . "/vendor/autoload.php";


$googleConfig = (new ConfigFactory())->build();
$exporter = (new StackdriverExporterFactory($googleConfig))->build();
(new TraceService($exporter))->start();

$message = Tracer::inSpan(
    ['name' => 'consume-message'],
    function () {
        $rawMessage = file_get_contents('php://input');

        if ($rawMessage === false) {
            error_log("No body");
            return "";
        }

        $message = json_decode($rawMessage, true);

        if (json_last_error() !== JSON_ERROR_NONE) {
            error_log("Invalid message: " . $rawMessage);
        }

        return $message;
    }
);

Tracer::inSpan(
    ['name' => 'render'],
    function () use ($message) {
        if (json_last_error() !== JSON_ERROR_NONE) {
            http_response_code(400);
        }

        http_response_code(204);

        $decodedMessage = base64_decode($message['message']['data']);

        if ($decodedMessage === false) {
            error_log("Could not base64 decode message:" . $message['message']['data']);
            return;
        }
        
        error_log($decodedMessage);
    }
);

MessageSenderService.php

<?php


namespace Armakuni\Demo\PhpInserter;


use Google\Cloud\PubSub\PubSubClient;

class MessageSenderService
{
    /**
     * @var PubSubClient
     */
    private $pubSubClient;
    /**
     * @var string
     */
    private $topic;

    /**
     * CounterService constructor.
     * @param PubSubClient $pubSubClient
     * @param string $topic
     */
    public function __construct(PubSubClient $pubSubClient, string $topic)
    {
        $this->pubSubClient = $pubSubClient;
        $this->topic = $topic;
    }

    /**
     * @param string $message
     * @return void
     */
    public function sendMessage(string $message): void
    {
        $topic = $this->pubSubClient->topic($this->topic);
        if (!$topic->exists()) {
            $topic->create();
        }


        $topic->publish(['data' => $message]);
    }
}