def vhost_get_default_server(config, default):
    """Get vhost default directive which makes it the default vhost."""
    if default:
        if config['server'] == 'nginx':
            # The leading space is required here for the template to
            # separate it from the port directive left to it.
            return ' default_server'
        elif config['server'] in ('apache22', 'apache24'):
            return '_default_'
    else:
        if config['server'] in ('apache22', 'apache24'):
            return '*'
    return ''