github webhook を利用した、push すると自動で git pull する感じのアレ

hook.php

<?php

header('Content-Type: application/json');
$secret = 'hogehoge';
$repo = 'hoge';

function generate_response($code) {
    $response = array(
        '200' => array(
            'status' => 'success',
            'errors' => null
        ),
        '400' => array(
            'status' => 'fail',
            'errors' => array(
                'code' => '400',
                'message' => 'Invalid request.'
        )),
        '401' => array(
            'status' => 'fail',
            'errors' => array(
                'code' => '401',
                'message' => 'Could not authenticate.'
        ))
    );
    return json_encode($response[$code]);
}

if (!isset($_SERVER['HTTP_X_HUB_SIGNATURE'])) {
    header('HTTP/1.1 400 Bad Request');
    print generate_response(400);
    die();
}

$json_str = file_get_contents('php://input');
$json_obj = json_decode($json_str);
$signature = substr($_SERVER['HTTP_X_HUB_SIGNATURE'], 5);
$hash = hash_hmac('sha1', $json_str, $secret);

if (($hash !== $signature) || ($json_obj->repository->name !== $repo)) {
    header('HTTP/1.1 401 Unauthorized');
    print generate_response(401);
    die();
} else {
    `cd ./repository; git pull`;
    print generate_response(200);
    die();
}