.. _host-images:

===========
Host Images
===========

StackHPC Kayobe configuration provides configuration for some standard
overcloud host images, built using the :kayobe-doc:`overcloud DIB
<configuration/reference/overcloud-dib.html>` functionality of Kayobe.

The overcloud DIB configuration is provided in
``etc/kayobe/stackhpc-overcloud-dib.yml``. It is not used by default, and must
be actively opted into. This can be done as follows:

.. code-block:: yaml
   :caption: ``etc/kayobe/overcloud-dib.yml``

   overcloud_dib_build_host_images: true

   overcloud_dib_host_images:
     - "{{ stackhpc_overcloud_dib_host_image }}"

The image name is configured via ``stackhpc_overcloud_dib_name``, and is
``deployment_image`` by default.

The list of DIB elements is configured via ``stackhpc_overcloud_dib_elements``.
The default value depends on the ``os_distribution`` variable. See the YAML
file for details.

The DIB environment variables are configured via
``stackhpc_overcloud_dib_env_vars``. See the YAML file for details.

A list of packages to install is configured via
``stackhpc_overcloud_dib_packages``.

By default, a UEFI-compatible image is built that uses separate LVM volumes for
different mount points. This is done to pass Centre for Internet Security (CIS)
partition benchmarks. The block device YAML configuration is configured via
``stackhpc_overcloud_dib_block_device_config_uefi_lvm``.

The 3 partitions are:

* p0: EFI ESP bootloader
* p1: EFI BSP
* p2: LVM PV (``rootpv``)

The LVM Logical Volumes are:

============== ================== =========
LV             Mount point        Size (GB)
============== ================== =========
``lv_root``    ``/``              5G
``lv_tmp``     ``/tmp``           1G
``lv_var``     ``/var``           1G
``lv_var_tmp`` ``/var/tmp``       1G
``lv_log``     ``/var/log``       1G
``lv_audit``   ``/var/log/audit`` 128M
``lv_home``    ``/home``          128M
============== ================== =========

A compatible LVM configuration is provided, and covered in :ref:`lvm`.
The Logical Volumes in the image are defined with small sizes, with the
intention that they will be grown after provisioning.

For RedHat family distributions, Dracut modules are configured via
``stackhpc_overcloud_dib_dracut_enabled_modules_default_config``.