Add preflight checks for cgroup kernel params in k3s setup

- Ensure cgroup kernel parameters are present before k3s installation.
- Introduce playbook changes to integrate cgroup prerequisites role.

infrastructure/playbooks/site.yml

@@ -23,6 +23,13 @@
     - local_user
     - rsyslog
 
+- name: K3s cgroup prerequisites
+  hosts: k3s_hosts
+  become: true
+  serial: 1
+  roles:
+    - cgroups
+
 - name: K3s Cluster Setup
   hosts: k3s_hosts
   become: true

infrastructure/roles/k3s/tasks/main.yml

@@ -35,6 +35,16 @@
   changed_when: false
   failed_when: rancher_mounted.rc != 0
 
+- name: Preflight - ensure cgroup kernel params are present
+  ansible.builtin.command: "cat /proc/cmdline"
+  register: k3s_proc_cmdline
+  changed_when: false
+
+- name: Fail if cgroup params are missing (reboot required)
+  ansible.builtin.fail:
+    msg: "Missing cgroup params in /proc/cmdline: {{ ['cgroup_memory=1', 'cgroup_enable=memory'] | reject('in', k3s_proc_cmdline.stdout) | list }}. Reboot required before k3s install."
+  when: (['cgroup_memory=1', 'cgroup_enable=memory'] | reject('in', k3s_proc_cmdline.stdout) | list) | length > 0
+
 - name: Guardrail - ensure rancher mountpoint is not on SD/rootfs
   ansible.builtin.command: "findmnt -n -o SOURCE {{ k3s_rancher_mountpoint | default('/var/lib/rancher') }}"
   register: rancher_source