Return the salt_interface type to connect to. Either 'public_ips' (default)
    or 'private_ips'.

def get_salt_interface(vm_, opts):
    '''
    Return the salt_interface type to connect to. Either 'public_ips' (default)
    or 'private_ips'.
    '''
    salt_host = salt.config.get_cloud_config_value(
        'salt_interface', vm_, opts, default=False,
        search_global=False
    )

    if salt_host is False:
        salt_host = salt.config.get_cloud_config_value(
            'ssh_interface', vm_, opts, default='public_ips',
            search_global=False
        )

    return salt_host