Update Azure udev rules workaround for WALinuxAgent

For RHEL 8.6, we no longer need the 25rhcos-azure-udev-rules overlay
because the WALinuxAgent-udev package exists. We do still need the glue
code that copies the udev files into the initramfs via a dracut module,
thought. This is not needed for RHEL 9.0.

This migrates the glue code that installs the udev rules into the
initramfs to an overlay module in the RHCOS repo for 8.6. It was no
longer needed in FCOS and removed from the overlay there in [1].

[1] coreos/fedora-coreos-config#1686

From: #785

common.yaml

@@ -29,7 +29,6 @@ ostree-layers:
   - overlay/15rhcos-tuned-bits
   - overlay/20platform-chrony
   - overlay/21dhcp-chrony
-  - overlay/25rhcos-azure-udev-rules
 
 arch-include:
   x86_64:

overlay.d/25rhcos-azure-udev/usr/lib/dracut/modules.d/25rhcos-azure-udev/module-setup.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+# -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-
+# ex: ts=8 sw=4 sts=4 et filetype=sh
+
+# We want to provide Azure udev rules as part of the initrd, so that Ignition
+# is able to detect disks and act on them.
+#
+# The WALinuxAgent-udev has been changed to install udev rules into
+# the initramfs [1], but that change isn't in el8 yet. This can be
+# dropped when moving to el9.
+#
+# [1] https://src.fedoraproject.org/rpms/WALinuxAgent/c/521b67bc8575f53a30b4b2c4e63292e67483a4e1?branch=rawhide
+
+install() {
+    inst_multiple \
+        /usr/lib/udev/rules.d/66-azure-storage.rules \
+        /usr/lib/udev/rules.d/99-azure-product-uuid.rules
+}

overlay.d/README.md

@@ -41,8 +41,20 @@ https://listengine.tuxfamily.org/chrony.tuxfamily.org/chrony-dev/2020/05/msg0002
 25rhcos-azure-udev-rules
 ------------------------
 
+RHEL 8.5 only
+
 Ships udev rules for Azure. This works in tandem with the
 `25coreos-azure-udev` dracut module in 05core which ships
 them in the initramfs. In the future, we should be able to
 drop this overlay and instead ship `WALinuxAgent-udev` as we
 do in FCOS (https://bugzilla.redhat.com/show_bug.cgi?id=1913074).
+
+25rhcos-azure-udev
+-------------
+
+RHEL 8.6 only
+
+We want to provide Azure udev rules as part of the initrd, so that Ignition is
+able to detect disks and act on them. The WALinuxAgent-udev has been changed to
+install udev rules into the initramfs, but that change isn't in el8 yet. This
+can be dropped when moving to el9.

rhel-8.5.yaml

@@ -2,6 +2,7 @@
 ostree-layers:
   # Temporary logrotate service and timer units
   - overlay/15rhcos-logrotate
+  - overlay/25rhcos-azure-udev-rules
 
 # See README.md
 # and https://github.com/openshift/release/blob/master/core-services/release-controller/README.md#rpm-mirrors

rhel-8.6.yaml

@@ -2,6 +2,7 @@
 ostree-layers:
   # Temporary logrotate service and timer units
   - overlay/15rhcos-logrotate
+  - overlay/25rhcos-azure-udev
 
 # See README.md
 # and https://github.com/openshift/release/blob/master/core-services/release-controller/README.md#rpm-mirrors