support raid root disks in stackhpc-built images

Author: sjpb

ansible/.gitignore

@@ -98,3 +98,5 @@ roles/*
 !roles/eessi/**
 !roles/topology/
 !roles/topology/**
+!roles/raid/
+!roles/raid/**

ansible/extras.yml

@@ -1,3 +1,12 @@
+- hosts: raid
+  become: yes
+  gather_facts: no
+  tags: raid
+  name: Configure image for baremetal software raid root disks
+  tasks:
+    - include_role:
+        name: raid
+
 - hosts: k3s_server:!builder
   become: yes
   tags: k3s

ansible/roles/raid/README.md

@@ -0,0 +1,13 @@
+# raid
+
+Configure an image to support software raid (via [mdadm](https://github.com/md-raid-utilities/mdadm)).
+
+RockyLinux genericcloud images already have the necessary `mdraid` dracut
+module installed, as well as kernel modules for `raid0`, `raikd1`, `raid10` and
+`raid456` [^1]. This covers all raid modes [supported by Ironic](https://docs.openstack.org/ironic/latest/admin/raid.html#software-raid)
+hence this role does not support extending this.
+
+This role changes the command line for the current kernel. It does not reboot
+the instance so generally is only useful during image builds.
+
+[^1]: As shown by `lsinitrd /boot/initramfs-$(uname -r).img | grep raid`

ansible/roles/raid/tasks/main.yml

@@ -0,0 +1,13 @@
+- name: Enable autoassembly of mdraid devices
+  # adds rd.auto=1 - see `man dracut.cmdline`
+  ansible.builtin.lineinfile:
+    path: /etc/default/grub
+    regexp: '^GRUB_CMDLINE_LINUX_DEFAULT="((?:(?!rd.auto=1).)*?)"$'
+    line: 'GRUB_CMDLINE_LINUX_DEFAULT="\1 rd.auto=1"'
+    backup: true
+    backrefs: true
+  register: update_grub
+  
+- name: Update GRUB configuration file
+  command: grub2-mkconfig -o /boot/grub2/grub.cfg --update-bls-cmdline
+  when: update_grub.changed

environments/.stackhpc/inventory/extra_groups

@@ -50,3 +50,7 @@ cluster
 
 [compute_init:children]
 compute
+
+[raid:children]
+# Configure fatimage for raid
+builder

environments/common/inventory/groups

@@ -218,3 +218,5 @@ extra_packages
 # pulp_host ansible_host=<VM-ip-address>
 # Note the host name can't conflict with group names i.e can't be called `pulp` or `pulp_server`
 
+[raid]
+# Add `builder` to configure image for software raid

environments/site/inventory/groups

@@ -166,3 +166,6 @@ compute
 # separately from the appliance. e.g
 # pulp_host ansible_host=<VM-ip-address>
 # Note inventory host name cannot conflict with group names i.e can't be called `pulp` or `pulp_server`.
+
+[raid]
+# Add `builder` to configure image for software raid