kernel: allow to override modules & sysctl settings

Allow to easily personalize Kernel modules and sysctl settings with two new parameters.
ExtraKernelModules and ExtraSysctlSettings are dictionaries that will take precedence
over the defaults settings provided in the composable service.

Closes-Bug: #1742440
Change-Id: I9cd43331e5e9a6074cd47040c29815ca32c61693

puppet/services/kernel.yaml

@@ -64,6 +64,14 @@ parameters:
     default: 1024
     description: Configures sysctl fs.inotify.max_user_instances key
     type: number
+  ExtraKernelModules:
+    default: {}
+    description: Hash of extra Kernel modules to load.
+    type: json
+  ExtraSysctlSettings:
+    default: {}
+    description: Hash of extra sysctl settings to apply.
+    type: json
 
 
 outputs:
@@ -73,10 +81,13 @@ outputs:
       service_name: kernel
       config_settings:
         kernel_modules:
-          nf_conntrack: {}
+          map_merge:
+            - nf_conntrack: {}
               nf_conntrack_proto_sctp: {}
+            - {get_param: ExtraKernelModules}
         sysctl_settings:
-          net.ipv4.tcp_keepalive_intvl:
+          map_merge:
+            - net.ipv4.tcp_keepalive_intvl:
                 value: 1
               net.ipv4.tcp_keepalive_probes:
                 value: 5
@@ -137,6 +148,7 @@ outputs:
               # set inotify value for neutron/dnsmasq scale
               fs.inotify.max_user_instances:
                 value: {get_param: InotifyIntancesMax}
+            - {get_param: ExtraSysctlSettings}
 
       step_config: |
         include ::tripleo::profile::base::kernel

releasenotes/notes/kernel-extra-aa48704056be72cd.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Allow to easily personalize Kernel modules and sysctl settings with two new parameters.
+    ExtraKernelModules and ExtraSysctlSettings are dictionaries that will take precedence
+    over the defaults settings provided in the composable service.