path: root/doc/server/plugins/structures/bundler/index.txt

.. -*- mode: rst -*-
.. vim: ft=rst

.. _server-plugins-structures-bundler-index:

=======
Bundler
=======

Bundler is used to describe groups of inter-dependent configuration
entries, such as the combination of packages, configuration files,
and service activations that comprise typical Unix daemons. Bundles are
used to add groups of configuration entries to the inventory of client
configurations, as opposed to describing particular versions of those
entries. For example, a bundle could say that the configuration file
``/etc/passwd`` should be included in a configuration, but will not
describe the particular version of ``/etc/passwd`` that a given client
will receive.

Group and Client tags can be used inside of bundles to differentiate
which entries particular clients will recieve; this is useful for the
case where entries are named differently across systems; for example,
one linux distro may have a package called openssh while another uses
the name ssh. Configuration entries nested inside of Group elements
only apply to clients who are a member of those groups; multiple
nested groups must all apply. Also, groups may be negated; entries
included in such groups will only apply to clients who are not a
member of said group.  The same applies to Client elements.

The following is an annotated copy of a bundle:

.. code-block:: xml

    <Bundle name='ssh' version='2.0'>
      <Path name='/etc/ssh/ssh_host_dsa_key'/>
      <Path name='/etc/ssh/ssh_host_rsa_key'/>
      <Path name='/etc/ssh/ssh_host_dsa_key.pub'/>
      <Path name='/etc/ssh/ssh_host_rsa_key.pub'/>
      <Path name='/etc/ssh/ssh_host_key'/>
      <Path name='/etc/ssh/ssh_host_key.pub'/>
      <Path name='/etc/ssh/sshd_config'/>
      <Path name='/etc/ssh/ssh_config'/>
      <Path name='/etc/ssh/ssh_known_hosts'/>
      <Group name='rpm'>
        <Package name='openssh'/>
        <Package name='openssh-askpass'/>
        <Service name='sshd'/>
        <Group name='fedora' >
           <Group name='fc14' negate='true'>
             <Package name='openssh-clients'/>
           </Group>
           <Package name='openssh-server'/>
        </Group>
      </Group>
      <Group name='deb'>
        <Package name='ssh'/>
        <Service name='ssh'/>
      </Group>
      <Client name='trust.example.com'>
          <Path name='/etc/ssh/shosts.equiv'/>
      </Client>
    </Bundle>

In this bundle, most of the entries are common to all systems. Clients
in group **deb** get one extra package and service, while clients in
group **rpm** get two extra packages and an extra service. In
addition, clients in group **fedora** *and* group **rpm** get one
extra package entries, unless they are not in the **fc14** group, in
which case, they get an extra package. The client
**trust.example.com** gets one extra file that is not distributed to
any other clients.  Notice that this file doesn't describe which
versions of these entries that clients should get, only that they
should get them. (Admittedly, this example is slightly contrived, but
demonstrates how group entries can be used in bundles)

+----------------------------+-------------------------------+
| Group/Hostname             | Entry                         |
+============================+===============================+
| all                        | /etc/ssh/ssh_host_dsa_key     |
+----------------------------+-------------------------------+
| all                        | /etc/ssh/ssh_host_rsa_key     |
+----------------------------+-------------------------------+
| all                        | /etc/ssh/ssh_host_dsa_key.pub |
+----------------------------+-------------------------------+
| all                        | /etc/ssh/ssh_host_rsa_key.pub |
+----------------------------+-------------------------------+
| all                        | /etc/ssh/ssh_host_key         |
+----------------------------+-------------------------------+
| all                        | /etc/ssh/ssh_host_key.pub     |
+----------------------------+-------------------------------+
| all                        | /etc/ssh/sshd_config          |
+----------------------------+-------------------------------+
| all                        | /etc/ssh/ssh_config           |
+----------------------------+-------------------------------+
| all                        | /etc/ssh/ssh_known_hosts      |
+----------------------------+-------------------------------+
| rpm                        | Package openssh               |
+----------------------------+-------------------------------+
| rpm                        | Package openssh-askpass       |
+----------------------------+-------------------------------+
| rpm                        | Service sshd                  |
+----------------------------+-------------------------------+
| rpm and fedora             | Package openssh-server        |
+----------------------------+-------------------------------+
| rpm and fedora and not fc4 | Package openssh-clients       |
+----------------------------+-------------------------------+
| deb                        | Package ssh                   |
+----------------------------+-------------------------------+
| deb                        | Service ssh                   |
+----------------------------+-------------------------------+
| trust.example.com          | /etc/ssh/shosts.equiv         |
+----------------------------+-------------------------------+

Genshi templates
================

Genshi XML templates allow you to use the `Genshi
<http://genshi.edgewall.org>`_ templating system to dynamically generate
a bundle.  Genshi templates can be specified **one** of two ways:

* Add an XML-style genshi template to the Bundler directory with a
   ``.genshi`` and the associated namespace attribute.
* Simply add the appropriate namespace attribute to your existing XML
   bundle.

The top-level Bundle tag should look like the following::

    <Bundle name="foo" xmlns:py="http://genshi.edgewall.org/">

Several variables are pre-defined inside templates:

+-------------+--------------------------------------------------------+
| Name        | Description                                            |
+=============+========================================================+
| metadata    | :ref:`Client metadata                                  |
|             | <server-plugins-grouping-metadata-clientmetadata>`     |
+-------------+--------------------------------------------------------+
| repo        | The path to the Bcfg2 repository on the filesystem     |
+-------------+--------------------------------------------------------+

.. note::

    ``<Group>`` and ``<Client>`` tags are allowed inside of Genshi
    templates as of Bcfg2 1.2.  However, they do not behave the same
    as using a Genshi conditional, e.g.::

        <py:if test="'groupname' in metadata.groups">
	</py:if>

    The conditional is evaluated when the template is rendered, so
    code inside the conditional is not executed if the conditional
    fails.  A ``<Group>`` tag is evaluated *after* the template is
    rendered, so code inside the tag is always executed.  This is an
    important distinction: if you have code that will fail on some
    groups, you *must* use a Genshi conditional, not a ``<Group>``
    tag.  The same caveats apply to ``<Client>`` tags.

See also the :ref:`xml-genshi-reference`.

Troubleshooting
---------------

To render a bundle for a given client, you can run::

    bcfg2-info buildbundle <bundle name> <hostname>

This will render the template; it will not fully bind all of the
entries in the bundle.

See :ref:`bcfg2-info <server-bcfg2-info>` for more details.

Altsrc
======

.. toctree::
   :maxdepth: 1

   ../altsrc

Examples
========

In some cases, configuration files need to include the client's hostname
in their name. The following template produces such a config file entry.

.. code-block:: xml

    <Bundle name='foo'  xmlns:py="http://genshi.edgewall.org/">
        <Path name='/etc/package-${metadata.hostname}'/>
    </Bundle>

Depending on the circumstance, these configuration files can either be
handled by individual entries in :ref:`server-plugins-generators-cfg`,
or can be mapped to a single entry by using the
:ref:`server-plugins-structures-altsrc` feature.

In this example, configuration file names are built using probed results
from the client. getmac is a probe that gathers client MAC addresses
and returns them in a newline delimited string.

.. code-block:: xml

    <Bundle name="networkinterfaces" xmlns:py="http://genshi.edgewall.org/">
        <?python
          files = metadata.Probes["getmacs"].split("\n")
        ?>
        <Path py:for="file in files"
              name="/etc/sysconfig/network/ifcfg-eth-${file}"
              altsrc="/etc/ifcfg-template"/>
    </Bundle>

.. note::
   * The use of the altsrc directive causes all ifcfg files to be
     handled by the same plugin and entry.
   * The <?python ?> blocks have only been available in genshi since
     0.4 (http://genshi.edgewall.org/ticket/84)

If you want a file to be only on a per-client basis, you can use an
if declaration.

.. code-block:: xml

    <Bundle name='bacula' xmlns:py="http://genshi.edgewall.org/">
         <Path name="/etc/bacula/bconsole.conf"/>
         <Path name="/etc/bacula/bacula-fd.conf"/>
         <Path name="/etc/bacula/bacula-sd.conf"/>
         <Path py:if="metadata.hostname == 'foo.bar.com'"
               name="/etc/bacula/bacula-dir.conf"/>
    </Bundle>

or alternately

.. code-block:: xml

    <Bundle name='bacula' xmlns:py="http://genshi.edgewall.org/">
         <Path name="/etc/bacula/bconsole.conf"/>
         <Path name="/etc/bacula/bacula-fd.conf"/>
         <Path name="/etc/bacula/bacula-sd.conf"/>
         <py:if="metadata.hostname == 'foo.bar.com'">
           <Path name="/etc/bacula/bacula-dir.conf"/>
         </py:if>
    </Bundle>

or yet another way

.. code-block:: xml

    <Bundle name='bacula' xmlns:py="http://genshi.edgewall.org/">
        <Path name="/etc/bacula/bconsole.conf"/>
        <Path name="/etc/bacula/bacula-fd.conf"/>
        <Path name="/etc/bacula/bacula-sd.conf"/>
        <Client name="foo.bar.com">
            <Path name="/etc/bacula/bacula-dir.conf"/>
        </Client>
    </Bundle>

The final form is preferred if there is no code inside the block that
would fail on other clients.

While these examples are simple, the test in the if block can in fact
be any python statement.

.. _server-plugins-structures-bundler-index-examples:

Other examples
==============

Some simple examples of Bundles can be found in the `Bcfg2 example repository`_.

.. _Bcfg2 example repository: https://github.com/solj/bcfg2-repo

In addition to the example repository, the following is a list of some
more complex example Bundles.

.. toctree::
   :maxdepth: 1

   kernel
   moab
   nagios
   ntp
   snmpd
   torque
   yp