A slightly modified version of Brandon Summers' script. For more information: http://simianstudios.com/blog/post/using-bitbucket-for-automated-deployment-of-multiple-repositories

deploy.php

<?php

date_default_timezone_set('Europe/London'); // Set this to your local timezone - http://www.php.net/manual/en/timezones.php

/**
* The root directory where the repos live.
* 
* @var string
*/
$root_dir = '/your/root/dir/';
  
/**
* A list of repo slugs that the script is allowed to know about, and their
* locations relative to $root_dir.
* 
* @var array
*/
$repos = array(
  'repo-slug' => 'repo_location'
);

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 = '/your/log/dir/deploy.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')
  {
      echo $message;
      if ($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 where the magic happens
$slug = $_POST['repository']['slug'];

if($slug == '') { // check in the 'payload' param if the data isn't in the post body itself
	$post_data = json_decode(stripslashes($_POST['payload']), TRUE);
	$slug = $post_data['repository']['slug'];
}

if(array_key_exists($slug, $repos))
{
	$deploy = new Deploy($root_dir . $repos[$slug]);
	$deploy->execute();
}
elseif($slug == '')
{
	die('No repo specified.');
}
else
{
	die('Repo "' . $slug . '" has not been set up in the deploy script.');
}

?>

Hi Kris, thanks for sharing this. I'm getting an issue where by the hook will only work by logging into the server and running the file through SSH directly, like: php webhook.php (while in the correct directory). I did notice it asks for the password associated with the key, so I assume this could be why it's not working when I commit to the repo as perhaps it gets to the password bit and stops.

Additionally - can this run from outside of the project folder or a different directory, or can it only work from within the directory where git is initialized?

Sorry for the slow reply, I have just discovered that Github doesn't notify for Gist comments :(

Sounds like you need to regenerate your key without a password - this is allowed although not always obvious IIRC.

Yes, it should be able to run from any directory on the same server, as long as you use the correct relative or absolute paths.