webhook.php

<?php
/**
 * GitHub webhook handler for webtechdeploy projects.
 * 
 * @author  Sven Gehring <cbrxde@gmail.com> 
 * @author  Miloslav Hůla (https://github.com/milo)
 */

// This file is populated by entrypoint.sh to prevent env inconsistencies
$hookSecret = trim(file_get_contents("/etc/hook_secret"));

set_error_handler(function($severity, $message, $file, $line) {
	throw new \ErrorException($message, 0, $severity, $file, $line);
});

set_exception_handler(function($e) {
	header('HTTP/1.1 500 Internal Server Error');
	echo "Error on line {$e->getLine()}: " . htmlSpecialChars($e->getMessage());
	die();
});

$rawPost = NULL;

if ($hookSecret !== NULL) {
	if (!isset($_SERVER['HTTP_X_HUB_SIGNATURE'])) {
		throw new \Exception("HTTP header 'X-Hub-Signature' is missing.");
	} elseif (!extension_loaded('hash')) {
		throw new \Exception("Missing 'hash' extension to check the secret code validity.");
	}
	
	list($algo, $hash) = explode('=', $_SERVER['HTTP_X_HUB_SIGNATURE'], 2) + array('', '');
	if (!in_array($algo, hash_algos(), TRUE)) {
		throw new \Exception("Hash algorithm '$algo' is not supported.");
	}

	$rawPost = file_get_contents('php://input');
	if ($hash !== hash_hmac($algo, $rawPost, $hookSecret)) {
		throw new \Exception('Hook secret does not match.');
	}
};

if (!isset($_SERVER['HTTP_CONTENT_TYPE'])) {
	throw new \Exception("Missing HTTP 'Content-Type' header.");
} elseif (!isset($_SERVER['HTTP_X_GITHUB_EVENT'])) {
	throw new \Exception("Missing HTTP 'X-Github-Event' header.");
}

switch ($_SERVER['HTTP_CONTENT_TYPE']) {
	case 'application/json':
		$json = $rawPost ?: file_get_contents('php://input');
		break;

	case 'application/x-www-form-urlencoded':
		$json = $_POST['payload'];
		break;

	default:
		throw new \Exception("Unsupported content type: $_SERVER[HTTP_CONTENT_TYPE]");
}

$payload = json_decode($json);
switch (strtolower($_SERVER['HTTP_X_GITHUB_EVENT'])) {
	case 'ping':
		echo 'pong';
		break;

	case 'push':
		var_dump(shell_exec("sudo /usr/sbin/update.sh"));
		break;

	default:
		header('HTTP/1.0 404 Not Found');
		echo "Event:$_SERVER[HTTP_X_GITHUB_EVENT] Payload:\n";
		print_r($payload); # For debug only. Can be found in GitHub hook log.
		die();
}