Fix idempotence for web ui enablement.

README.md

@@ -30,7 +30,7 @@ TODO.
 
 TODO.
 
-    kubernetes_enable_web_ui: True
+    kubernetes_enable_web_ui: False
 
 TODO.
 

tasks/main.yml

@@ -75,6 +75,14 @@
     - kubernetes_allow_pods_on_master
     - kubernetes_init_stat.stat.exists == False
 
+- name: Check if Kubernetes Dashboard UI service already exists.
+  shell: kubectl get services --namespace kube-system | grep -q kubernetes-dashboard
+  changed_when: False
+  register: kubernetes_dashboard_service
+  when: kubernetes_enable_web_ui
+
 - name: Enable the Kubernetes Web Dashboard UI (if configured).
   command: "kubectl create -f https://raw.githubusercontent.com/kubernetes/dashboard/master/src/deploy/recommended/kubernetes-dashboard.yaml"
-  when: kubernetes_enable_web_ui
+  when:
+    - kubernetes_enable_web_ui
+    - kubernetes_dashboard_service is failed