# Copyright (C) 2011 Canonical Ltd.
# Copyright (C) 2012, 2013 Hewlett-Packard Development Company, L.P.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

"""
Update Hostname
---------------
**Summary:** update hostname and fqdn

This module will update the system hostname and fqdn. If ``preserve_hostname``
is set, then the hostname will not be altered.

.. note::
    for instructions on specifying hostname and fqdn, see documentation for
    ``cc_set_hostname``

**Internal name:** ``cc_update_hostname``

**Module frequency:** always

**Supported distros:** all

**Config keys**::

    preserve_hostname: <true/false>
    prefer_fqdn_over_hostname: <true/false>
    fqdn: <fqdn>
    hostname: <fqdn/hostname>
"""

import os

from cloudinit import util
from cloudinit.settings import PER_ALWAYS

frequency = PER_ALWAYS


def handle(name, cfg, cloud, log, _args):
    if util.get_cfg_option_bool(cfg, "preserve_hostname", False):
        log.debug(
            "Configuration option 'preserve_hostname' is set,"
            " not updating the hostname in module %s",
            name,
        )
        return

    # Set prefer_fqdn_over_hostname value in distro
    hostname_fqdn = util.get_cfg_option_bool(
        cfg, "prefer_fqdn_over_hostname", None
    )
    if hostname_fqdn is not None:
        cloud.distro.set_option("prefer_fqdn_over_hostname", hostname_fqdn)

    (hostname, fqdn) = util.get_hostname_fqdn(cfg, cloud)
    try:
        prev_fn = os.path.join(cloud.get_cpath("data"), "previous-hostname")
        log.debug("Updating hostname to %s (%s)", fqdn, hostname)
        cloud.distro.update_hostname(hostname, fqdn, prev_fn)
    except Exception:
        util.logexc(
            log, "Failed to update the hostname to %s (%s)", fqdn, hostname
        )
        raise


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