Running hoster specific tasks like git pull for development

We need a way to classify (taxonomy?) a site and then execute some shell tasks.

Right now we have some developer/themer Aegir hosted sites under git revision control. We need a way to automate their git push so the changes reach the Aegir hosted sites. Some of these need to follow the git branch when getting cloned.

Based on the experiment below we think this needs a hosting module producing task nodes based on shell tasks available. Is this a possible solution? Producing task nodes every 5 minutes? How could we accomplish this?

The small example below generates a cronjob task list based on taxonomy terms added to the site nodes. For this example to work the taxonomy module must be enabled within the hostmaster site, the array keys from $tasks must match a taxonomy term. This has some limitations ...
- using hosting_cron_get_sites which has nothing to do with these tasks (used as a convinience now)
- generating crontab items is not aware of new or deleted sites.
- not using hosting cron

$tasks = array(
  'git pull 5m' => array(
    'description' => 'Run a git pull every 5 minutes',
    'command' => 'cd %publish_path%/sites/%hosting_name%; git pull',
    'interval' => '*/5 * * * *',
    'args' => array('publish_path', 'hosting_name'),
  ),
  //'git follow master branch' => tbd
  //'git follow hosting_name branch' => tbd
);

$sites = hosting_cron_get_sites($limit = 500);

foreach ($sites as $s => $site) {
  $platform = node_load($site->platform);

  $vars = array(
    '%publish_path%' => $platform->publish_path,
    '%hosting_name%' => $site->hosting_name,
  );
  //print_r($platform);
  //print_r($site);
  foreach ($site->taxonomy as $term) {
    if (isset($tasks[$term->name])) {
      $task = $tasks[$term->name];
      $command = $task['command'];
      $command = str_replace(array_keys($vars), array_values($vars), $command);
      echo $task['interval'] . " " . $command . "\n";
    }
  }
}

The output looks like

drush @hostmaster php-script taxonomy_runner.php 
*/5 * * * * cd /var/aegir/platforms/drupal-6.22/sites/test.example.com; git pull