PHP webhook script (bitbucket)

I'm trying to attempt using a webhook script so that I can just commit locally and have the script triggered server-side and pull in any change.

Now if I login to the server via SSH and run php webhook.php the cript is triggered successfully and the files are updated. So I know the file does work. But if I make edits to the files, commit and push to master, I'm not seeing the files updated.

The log file produced by the script suggests everything is fine, but clearly it's not.

My file structure is like this:

var
  www
    my-project
    - webhook.php
       repo-folder

So the file should be pulling the files into repo-folder and the webhook.php is set as the webhook via the bitbucket control panel. If I view the log within bitbucket, it's showing a successful request every time I push a commit.

The script:

<?php

date_default_timezone_set('Europe/London');

class Deploy {

    /**
     * A callback function to call after the deploy has finished.
     *
     * @var callback
     */
    public $post_deploy;

    /**
     * The name of the file that will be used for logging deployments. Set to
     * FALSE to disable logging.
     *
     * @var string
     */
    private $_log = 'deployments.log';

    /**
     * The timestamp format used for logging.
     *
     * @link    http://www.php.net/manual/en/function.date.php
     * @var     string
     */
    private $_date_format = 'Y-m-d H:i:sP';

    /**
     * The name of the branch to pull from.
     *
     * @var string
     */
    private $_branch = 'master';

    /**
     * The name of the remote to pull from.
     *
     * @var string
     */
    private $_remote = 'origin';

    /**
     * The directory where your website and git repository are located, can be
     * a relative or absolute path
     *
     * @var string
     */
    private $_directory;

    /**
     * Sets up defaults.
     *
     * @param  string  $directory  Directory where your website is located
     * @param  array   $data       Information about the deployment
     */
    public function __construct($directory, $options = array())
    {
        // Determine the directory path
        $this->_directory = realpath($directory).DIRECTORY_SEPARATOR;

        $available_options = array('log', 'date_format', 'branch', 'remote');

        foreach ($options as $option => $value)
        {
            if (in_array($option, $available_options))
            {
                $this->{'_'.$option} = $value;
            }
        }

        $this->log('Attempting deployment...');
    }

    /**
     * Writes a message to the log file.
     *
     * @param  string  $message  The message to write
     * @param  string  $type     The type of log message (e.g. INFO, DEBUG, ERROR, etc.)
     */
    public function log($message, $type = 'INFO')
    {
        if ($this->_log)
        {
            // Set the name of the log file
            $filename = $this->_log;

            if ( ! file_exists($filename))
            {
                // Create the log file
                file_put_contents($filename, '');

                // Allow anyone to write to log files
                chmod($filename, 0666);
            }

            // Write the message into the log file
            // Format: time --- type: message
            file_put_contents($filename, date($this->_date_format).' --- '.$type.': '.$message.PHP_EOL, FILE_APPEND);
        }
    }

    /**
     * Executes the necessary commands to deploy the website.
     */
    public function execute()
    {
        try
        {
            // Make sure we're in the right directory
            chdir($this->_directory);
            $this->log('Changing working directory... ');

            // Discard any changes to tracked files since our last deploy
            exec('git reset --hard HEAD', $output);
            $this->log('Reseting repository... '.implode(' ', $output));

            // Update the local repository
            exec('git pull '.$this->_remote.' '.$this->_branch, $output);
            $this->log('Pulling in changes... '.implode(' ', $output));

            // Secure the .git directory
            exec('chmod -R og-rx .git');
            $this->log('Securing .git directory... ');

            if (is_callable($this->post_deploy))
            {
                call_user_func($this->post_deploy, $this->_data);
            }

            $this->log('Deployment successful.');
        }
        catch (Exception $e)
        {
            $this->log($e, 'ERROR');
        }
    }

}

// This is just an example
$deploy = new Deploy('/var/www/site-name/repo-name');

$deploy->execute();

?>