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# Copyright (C) 2013 Craig Tracey
# Copyright (C) 2013 Hewlett-Packard Development Company, L.P.
#
# Author: Craig Tracey <craigtracey@gmail.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
#
# This file is part of cloud-init. See LICENSE file for license information.
"""Resolv Conf: configure resolv.conf"""
from textwrap import dedent
from cloudinit import log as logging
from cloudinit import templater, util
from cloudinit.config.schema import MetaSchema, get_meta_doc
from cloudinit.settings import PER_INSTANCE
LOG = logging.getLogger(__name__)
RESOLVE_CONFIG_TEMPLATE_MAP = {
"/etc/resolv.conf": "resolv.conf",
"/etc/systemd/resolved.conf": "systemd.resolved.conf",
}
MODULE_DESCRIPTION = """\
This module is intended to manage resolv.conf in environments where early
configuration of resolv.conf is necessary for further bootstrapping and/or
where configuration management such as puppet or chef own DNS configuration.
As Debian/Ubuntu will, by default, utilize resolvconf, and similarly Red Hat
will use sysconfig, this module is likely to be of little use unless those
are configured correctly.
When using a :ref:`datasource_config_drive` and a RHEL-like system,
resolv.conf will also be managed automatically due to the available
information provided for DNS servers in the :ref:`network_config_v2` format.
For those that with to have different settings, use this module.
In order for the ``resolv_conf`` section to be applied, ``manage_resolv_conf``
must be set ``true``.
.. note::
For Red Hat with sysconfig, be sure to set PEERDNS=no for all DHCP
enabled NICs.
.. note::
And, in Ubuntu/Debian it is recommended that DNS be configured via the
standard /etc/network/interfaces configuration file.
"""
meta: MetaSchema = {
"id": "cc_resolv_conf",
"name": "Resolv Conf",
"title": "Configure resolv.conf",
"description": MODULE_DESCRIPTION,
"distros": ["alpine", "fedora", "opensuse", "photon", "rhel", "sles"],
"frequency": PER_INSTANCE,
"examples": [
dedent(
"""\
manage_resolv_conf: true
resolv_conf:
nameservers:
- 8.8.8.8
- 8.8.4.4
searchdomains:
- foo.example.com
- bar.example.com
domain: example.com
sortlist:
- 10.0.0.1/255
- 10.0.0.2
options:
rotate: true
timeout: 1
"""
)
],
}
__doc__ = get_meta_doc(meta)
def generate_resolv_conf(template_fn, params, target_fname):
flags = []
false_flags = []
if "options" in params:
for key, val in params["options"].items():
if isinstance(val, bool):
if val:
flags.append(key)
else:
false_flags.append(key)
for flag in flags + false_flags:
del params["options"][flag]
if not params.get("options"):
params["options"] = {}
params["flags"] = flags
LOG.debug("Writing resolv.conf from template %s", template_fn)
templater.render_to_file(template_fn, target_fname, params)
def handle(name, cfg, cloud, log, _args):
"""
Handler for resolv.conf
@param name: The module name "resolv-conf" from cloud.cfg
@param cfg: A nested dict containing the entire cloud config contents.
@param cloud: The L{CloudInit} object in use.
@param log: Pre-initialized Python logger object to use for logging.
@param args: Any module arguments from cloud.cfg
"""
if "manage_resolv_conf" not in cfg:
log.debug(
"Skipping module named %s,"
" no 'manage_resolv_conf' key in configuration",
name,
)
return
if not util.get_cfg_option_bool(cfg, "manage_resolv_conf", False):
log.debug(
"Skipping module named %s,"
" 'manage_resolv_conf' present but set to False",
name,
)
return
if "resolv_conf" not in cfg:
log.warning("manage_resolv_conf True but no parameters provided!")
return
try:
template_fn = cloud.get_template_filename(
RESOLVE_CONFIG_TEMPLATE_MAP[cloud.distro.resolve_conf_fn]
)
except KeyError:
log.warning("No template found, not rendering resolve configs")
return
generate_resolv_conf(
template_fn=template_fn,
params=cfg["resolv_conf"],
target_fname=cloud.distro.resolve_conf_fn,
)
return
# vi: ts=4 expandtab
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