def get_id(opts, cache_minion_id=False):
    '''
    Guess the id of the minion.

    If CONFIG_DIR/minion_id exists, use the cached minion ID from that file.
    If no minion id is configured, use multiple sources to find a FQDN.
    If no FQDN is found you may get an ip address.

    Returns two values: the detected ID, and a boolean value noting whether or
    not an IP address is being used for the ID.
    '''
    if opts['root_dir'] is None:
        root_dir = salt.syspaths.ROOT_DIR
    else:
        root_dir = opts['root_dir']

    config_dir = salt.syspaths.CONFIG_DIR
    if config_dir.startswith(salt.syspaths.ROOT_DIR):
        config_dir = config_dir.split(salt.syspaths.ROOT_DIR, 1)[-1]

    # Check for cached minion ID
    id_cache = os.path.join(root_dir,
                            config_dir.lstrip(os.path.sep),
                            'minion_id')

    if opts.get('minion_id_caching', True):
        try:
            with salt.utils.files.fopen(id_cache) as idf:
                name = salt.utils.stringutils.to_unicode(idf.readline().strip())
                bname = salt.utils.stringutils.to_bytes(name)
                if bname.startswith(codecs.BOM):  # Remove BOM if exists
                    name = salt.utils.stringutils.to_str(bname.replace(codecs.BOM, '', 1))
            if name and name != 'localhost':
                log.debug('Using cached minion ID from %s: %s', id_cache, name)
                return name, False
        except (IOError, OSError):
            pass
    if '__role' in opts and opts.get('__role') == 'minion':
        log.debug(
            'Guessing ID. The id can be explicitly set in %s',
            os.path.join(salt.syspaths.CONFIG_DIR, 'minion')
        )

    if opts.get('id_function'):
        newid = call_id_function(opts)
    else:
        newid = salt.utils.network.generate_minion_id()

    if opts.get('minion_id_lowercase'):
        newid = newid.lower()
        log.debug('Changed minion id %s to lowercase.', newid)

    # Optionally remove one or many domains in a generated minion id
    if opts.get('minion_id_remove_domain'):
        newid = remove_domain_from_fqdn(opts, newid)

    if '__role' in opts and opts.get('__role') == 'minion':
        if opts.get('id_function'):
            log.debug(
                'Found minion id from external function %s: %s',
                opts['id_function'], newid
            )
        else:
            log.debug('Found minion id from generate_minion_id(): %s', newid)
    if cache_minion_id and opts.get('minion_id_caching', True):
        _cache_id(newid, id_cache)
    is_ipv4 = salt.utils.network.is_ipv4(newid)
    return newid, is_ipv4