Role parameter for tripleo_kernel_defer_reboot

To help operators protect their workload, they can now enable the
KernelArgsDeferReboot role parameter. This will prevent the tripleo-kernel
ansible module from automatically rebooting nodes even if KernelArgs
were changed unexpectedly.

Change-Id: I52e43f264a03775b6d609444f8da1a36d9565281

deployment/kernel/kernel-boot-params-baremetal-ansible.yaml

@@ -35,6 +35,19 @@ parameters:
     description: Kernel Args to apply to the host
     tags:
       - role_specific
+  KernelArgsDeferReboot:
+    default: false
+    type: boolean
+    description: >
+      When enabled, nodes will not get rebooted automatically by tripleo-kernel
+      if KernelArgs have been changed. Operators will have to manually reboot
+      nodes after the deployment or update process is completed.
+
+      Leaving this enabled during a scale-up operation will prevent reboot on
+      new nodes. This might cause deployment errors as the KernelArgs will not
+      be applied.
+    tags:
+      - role_specific
   TunedProfileName:
     default: 'throughput-performance'
     type: string
@@ -66,11 +79,13 @@ resources:
             - tuned_profile: TunedProfileName
               isolated_cores: IsolCpusList
               kernel_args: KernelArgs
+              kernel_args_defer_reboot: KernelArgsDeferReboot
             - values: {get_param: [RoleParameters]}
           - values:
               TunedProfileName: {get_param: TunedProfileName}
               IsolCpusList: {get_param: IsolCpusList}
               KernelArgs: {get_param: KernelArgs}
+              KernelArgsDeferReboot: {get_param: KernelArgsDeferReboot}
 
 outputs:
   role_data:
@@ -94,6 +109,7 @@ outputs:
             tasks_from: kernelargs.yml
           vars:
             tripleo_kernel_args: {get_attr: [RoleParametersValue, value, kernel_args]}
+            tripleo_kernel_defer_reboot: {get_attr: [RoleParametersValue, value, kernel_args_defer_reboot]}
             tripleo_kernel_reboot_timeout: {get_param: NodeRebootWaitTimeout}
       upgrade_tasks:
         - name: upgrade prepare for leapp to align kernel arg shortcommings in leapp

releasenotes/notes/add-parameter-kernelargsdeferreboot-5b8e8b2f64c64a91.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    To help operators protect their workload, they can now enable the
+    KernelArgsDeferReboot role parameter. This will prevent the tripleo-kernel
+    ansible module from automatically rebooting nodes even if KernelArgs
+    were changed unexpectedly.