Return a list of machine names for active virtual machine on the host,
    which are defined in the Vagrantfile at the indicated path.

    CLI Example:

    .. code-block:: bash

        salt '*' vagrant.list_active_vms  cwd=/projects/project_1

def list_active_vms(cwd=None):
    '''
    Return a list of machine names for active virtual machine on the host,
    which are defined in the Vagrantfile at the indicated path.

    CLI Example:

    .. code-block:: bash

        salt '*' vagrant.list_active_vms  cwd=/projects/project_1
    '''
    vms = []
    cmd = 'vagrant status'
    reply = __salt__['cmd.shell'](cmd, cwd=cwd)
    log.info('--->\n%s', reply)
    for line in reply.split('\n'):  # build a list of the text reply
        tokens = line.strip().split()
        if len(tokens) > 1:
            if tokens[1] == 'running':
                vms.append(tokens[0])
    return vms