Add an option to reserve resources for OS system daemons (#5007)

inventory/sample/group_vars/k8s-cluster/k8s-cluster.yml

@@ -191,6 +191,15 @@ podsecuritypolicy_enabled: false
 # Acceptable options are 'pods', 'system-reserved', 'kube-reserved' and ''. Default is "".
 # kubelet_enforce_node_allocatable: pods
 
+## Optionally reserve resources for OS system daemons.
+# system_reserved: true
+## Uncomment to override default values
+# system_memory_reserved: 512M
+# system_cpu_reserved: 500m
+## Reservation for master hosts
+# system_master_memory_reserved: 256M
+# system_master_cpu_reserved: 250m
+
 # An alternative flexvolume plugin directory
 # kubelet_flexvolumes_plugins_dir: /usr/libexec/kubernetes/kubelet-plugins/volume/exec
 

roles/kubernetes/node/templates/kubelet-config.v1beta1.yaml.j2

@@ -54,4 +54,14 @@ kubeReserved:
   cpu: {{ kube_cpu_reserved }}
   memory: {{ kube_memory_reserved|regex_replace('Mi', 'M') }}
 {% endif %}
-resolvConf: "{{ kube_resolv_conf }}"
\ No newline at end of file
+{% if system_reserved is defined and system_reserved %}
+systemReserved:
+{% if is_kube_master|bool %}
+  cpu: {{ system_master_cpu_reserved|default('250m') }}
+  memory: {{ system_master_memory_reserved|default('256M')|regex_replace('Mi', 'M') }}
+{% else %}
+  cpu: {{ system_cpu_reserved|default('500m') }}
+  memory: {{ system_memory_reserved|default('512M')|regex_replace('Mi', 'M') }}
+{% endif %}
+{% endif %}
+resolvConf: "{{ kube_resolv_conf }}"