"""
Create Etc Hosts
----------------
**Summary:** create ``/etc/hosts``

This module will create ``/etc/hosts`` file on first boot.
Management of ``/etc/hosts`` is controlled using ``create_etc_hosts``
directive.

If set to ``true`` , cloud-init will generate ``/etc/hosts``
using the template located in ``/etc/cloud/templates/create_hosts.dist.tmpl``.
In the ``/etc/cloud/templates/create_hosts.tmpl`` template, the strings
``$address``, ``$hostname`` and ``$fqdn`` will be replaced with the ipv4
address, hostname and fqdn respectively.

**Internal name:** ``cc_create_etc_hosts``

**Module frequency:** per instance

**Supported distros:** all

**Config keys**::

    create_etc_hosts: <true/false>
    localhost_interface: <interface>
"""

from cloudinit import templater
from cloudinit import util

from cloudinit.settings import PER_INSTANCE

frequency = PER_INSTANCE


def handle(name, cfg, cloud, log, _args):
    create_hosts = util.get_cfg_option_str(cfg, "create_etc_hosts", False)
    interface = util.get_cfg_option_str(cfg, "localhost_interface", 'eth0')
    if util.translate_bool(create_hosts, addons=['template']):
        (hostname, fqdn) = util.get_hostname_fqdn(cfg, cloud)
        if not hostname:
            log.warn(("Option 'create_etc_hosts' was set,"
                     " but no hostname was found"))
            hostname = 'localhost'
        address = util.get_ipv4_from_iface(interface)

        # Render from a template file
        tpl_fn_name = cloud.get_template_filename("create_hosts.%s" %
                                                  (cloud.distro.osfamily))
        if not tpl_fn_name:
            raise RuntimeError(("No hosts template could be"
                                " found for distro %s") %
                               (cloud.distro.osfamily))
        templater.render_to_file(tpl_fn_name, '/etc/hosts',
                                 {'hostname': hostname,
                                  'fqdn': fqdn,
                                  'address': address})
    else:
        log.debug(("Configuration option 'create_etc_hosts' is not set,"
                   " not creating /etc/hosts in module %s"), name)


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