Build overcloud host images via DIB by default

Changes overcloud_dib_build_host_images to true, as promised in
I93d242889e225b4e60254f6b9cc5eeb457294ac8.

Change-Id: I322432985535348fb4ebe5bff7db5dd68f16b340

ansible/inventory/group_vars/all/overcloud-dib

@@ -7,8 +7,8 @@
 # Whether to build host disk images with DIB directly instead of through
 # Bifrost. Setting it to true disables Bifrost image build and allows images to
 # be built with the `kayobe overcloud host image build` command. Default value
-# is {{ os_distribution == 'rocky' }}. This will change in a future release.
+# is true.
-overcloud_dib_build_host_images: "{{ os_distribution == 'rocky' }}"
+overcloud_dib_build_host_images: true
 
 # List of additional build host packages to install.
 overcloud_dib_host_packages_extra: []

doc/source/configuration/reference/bifrost.rst

@@ -42,7 +42,7 @@ Overcloud root disk image configuration
 .. note::
 
    This configuration only applies when ``overcloud_dib_build_host_images``
-   (set in ``${KAYOBE_CONFIG_PATH}/overcloud-dib.yml``) is not changed to true.
+   (set in ``${KAYOBE_CONFIG_PATH}/overcloud-dib.yml``) is changed to false.
 
 Bifrost uses Diskimage builder (DIB) to build a root disk image that is
 deployed to overcloud hosts when they are provisioned. The following options

doc/source/configuration/reference/overcloud-dib.rst

@@ -19,8 +19,7 @@ following option:
     Whether to build host disk images with DIB directly instead of through
     Bifrost. Setting it to true disables Bifrost image build and allows images
     to be built with the ``kayobe overcloud host image build`` command. Default
-    value is false, except on Rocky where it is true. This will change in a
+    value is true since the Zed release.
-    future release.
 
 With this option enabled, Bifrost will be configured to stop building a root
 disk image. This will become the default behaviour in a future release.

doc/source/deployment.rst

@@ -172,8 +172,8 @@ At this point the seed services need to be deployed on the seed VM.  These
 services are deployed in the ``bifrost_deploy`` container.
 
 This command will also build the Operating System image that will be used to
-deploy the overcloud nodes using Disk Image Builder (DIB), unless
+deploy the overcloud nodes using Disk Image Builder (DIB), if
-``overcloud_dib_build_host_images`` is set to ``True``.
+``overcloud_dib_build_host_images`` is set to ``False``.
 
 .. note::
 
@@ -229,8 +229,7 @@ Building Overcloud Host Disk Images
 .. note::
 
    This step is only relevant if ``overcloud_dib_build_host_images`` is set to
-   ``True``. By default, a host disk image is automatically built by Bifrost
+   ``True``, which is the default since the Zed release.
-   unless you're running Rocky Linux - which requires this step.
 
 Host disk images are deployed on overcloud hosts during provisioning. To build
 host disk images::

etc/kayobe/overcloud-dib.yml

@@ -7,7 +7,7 @@
 # Whether to build host disk images with DIB directly instead of through
 # Bifrost. Setting it to true disables Bifrost image build and allows images to
 # be built with the `kayobe overcloud host image build` command. Default value
-# is {{ os_distribution == 'rocky' }}. This will change in a future release.
+# is true.
 #overcloud_dib_build_host_images:
 
 # List of additional build host packages to install. Default is an empty list.

releasenotes/notes/overcloud-dib-default-dda199b09d40cb3b.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Overcloud host images are now built via DIB by default, rather than
+    Bifrost. The old behaviour may be obtained by setting
+    ``overcloud_dib_build_host_images`` to ``false``.