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cc_update_etc_hosts:
description: |
This module will update the contents of the local hosts database (hosts
file, usually ``/etc/hosts``) based on the hostname/FQDN specified in
config. Management of the hosts file is controlled using
``manage_etc_hosts``. If this is set to ``false``, cloud-init will not
manage the hosts file at all. This is the default behavior.
If set to ``true``, cloud-init will generate the hosts file using the
template located in ``/etc/cloud/templates/hosts.tmpl``. In the
``/etc/cloud/templates/hosts.tmpl`` template, the strings ``$hostname``
and ``$fqdn`` will be replaced with the hostname and FQDN respectively.
If ``manage_etc_hosts`` is set to ``localhost``, then cloud-init will not
rewrite the hosts file entirely, but rather will ensure that an entry for
the FQDN with a distribution-dependent IP is present (i.e.,
``ping <hostname>`` will ping ``127.0.0.1`` or ``127.0.1.1`` or other IP).
.. note::
If ``manage_etc_hosts`` is set to ``true``, the contents of the
``hosts`` file will be updated every boot. To make any changes to the
``hosts`` file persistent they must be made in
``/etc/cloud/templates/hosts.tmpl``.
.. note::
For instructions on specifying hostname and FQDN, see documentation for
the ``cc_set_hostname`` module.
examples:
- comment: >
Example 1: Do not update or manage ``/etc/hosts`` at all. This is the
default behavior. Whatever is present at instance boot time will be
present after boot. User changes will not be overwritten.
file: cc_update_etc_hosts/example1.yaml
- comment: >
Example 2: Manage ``/etc/hosts`` with cloud-init. On every boot,
``/etc/hosts`` will be re-written from
``/etc/cloud/templates/hosts.tmpl``.
The strings ``$hostname`` and ``$fqdn`` are replaced in the template
with the appropriate values, either from the config-config ``fqdn`` or
``hostname`` if provided. When absent, the meta-data will be
checked for ``local-hostname`` which can be split into
``<hostname>.<fqdn>``.
To make modifications persistent across a reboot, you must modify
``/etc/cloud/templates/hosts.tmpl``.
file: cc_update_etc_hosts/example2.yaml
- comment: >
Example 3: Update ``/etc/hosts`` every boot, providing a "localhost"
``127.0.1.1`` entry with the latest hostname and FQDN as provided by
either IMDS or cloud-config. All other entries will be left alone.
``ping hostname`` will ping ``127.0.1.1``.
file: cc_update_etc_hosts/example3.yaml
name: Update Etc Hosts
title: Update the hosts file (usually ``/etc/hosts``)
|
