[ffwd3] Ability to run scripts before reboot

In some cases depending on the environments we need to run
workarounds right before rebooting into Leapp Upgrade. We
now provide LeappPreRebootCommand which can be fed shell
script do do so.

Example on machine with nonworking console params user can
set in system_upgrade.yaml:
parameter_defaults:
  LeappPreRebootCommand:
    grubby --update-kernel=ALL --remove-args=console=ttyS0,115200n81
    grubby --update-kernel=ALL --remove-args=console=ttyS0

Resolves: rhbz#2196288
Change-Id: I1e30b3c00a56cc244ee1c5730ba22e1e33788bca

deployment/tripleo-packages/tripleo-packages-baremetal-puppet.yaml

@@ -120,6 +120,14 @@ parameters:
     type: comma_delimited_list
     tags:
       - role_specific
+  LeappPreRebootCommand:
+    type: string
+    description: |
+      Command or script snippet to run on all overcloud nodes to
+      apply any necessary workarounds before rebooting into Leapp.
+    default: ''
+    tags:
+      - role_specific
   UpgradeInitCommand:
     type: string
     description: |
@@ -182,6 +190,7 @@ resources:
               upgrade_leapp_actors_to_remove: LeappActorsToRemove
               upgrade_init_command: UpgradeInitCommand
               base_tripleo_packages: BaseTripleoPackages
+              leapp_pre_reboot_command: LeappPreRebootCommand
             - values: {get_param: [RoleParameters]}
           - values:
               DnfStreams: {get_param: DnfStreams}
@@ -190,6 +199,7 @@ resources:
               UpgradeLeappToRemove: {get_param: UpgradeLeappToRemove}
               UpgradeLeappToInstall: {get_param: UpgradeLeappToInstall}
               LeappUnloadKernelDrivers: {get_param: LeappUnloadKernelDrivers}
+              LeappPreRebootCommand: {get_param: LeappPreRebootCommand}
               LeappActorsToRemove: {get_param: LeappActorsToRemove}
               UpgradeInitCommand: {get_param: UpgradeInitCommand}
               LeappRepoInitCommand: {get_param: LeappRepoInitCommand}
@@ -374,6 +384,12 @@ outputs:
             - upgrade_leapp_enabled
             - "'Undercloud' not in group_names"
           block:
+            - name: Run LeappPreRebootCommand
+              shell:
+                list_join:
+                  - ''
+                  - - "#!/bin/bash\n\n"
+                    - {get_attr: [RoleParametersValue, value, 'leapp_pre_reboot_command']}
             - name: reboot to perform the upgrade
               reboot:
                 reboot_timeout: "{{upgrade_leapp_reboot_timeout}}"

releasenotes/notes/leapp-pre-reboot-command-7d7040d80ff132e4.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    Added LeappPreRebootCommand parameter to the tripleo-packages.
+    This is a list of commands to be executed just before rebooting the node
+    to perform the leapp upgrade.
+    This allows, for example, to remove kernel parameters to avoid affecting
+    the leapp reboot.