Upgrade kubernetes to V1.11.x (#3078)

Upgrade Kubernetes to V1.11.2
The kubeadm configuration file version has been upgraded from v1alpha1 to v1alpha2
Add bootstrap kubeadm-config.yaml with external etcd

roles/kubernetes/kubeadm/tasks/main.yml

@@ -27,23 +27,36 @@
   register: temp_token
   delegate_to: "{{ groups['kube-master'][0] }}"
 
+- name: gets the kubeadm version
+  command: "{{ bin_dir }}/kubeadm version -o short"
+  register: kubeadm_output
+
+- name: sets kubeadm api version to v1alpha1
+  set_fact:
+    kubeadmConfig_api_version: v1alpha1
+  when: kubeadm_output.stdout|version_compare('v1.11.0', '<')
+
+- name: defaults kubeadm api version to v1alpha2
+  set_fact:
+    kubeadmConfig_api_version: v1alpha2
+  when: kubeadm_output.stdout|version_compare('v1.11.0', '>=')
+
 - name: Create kubeadm client config
   template:
-    src: kubeadm-client.conf.j2
-    dest: "{{ kube_config_dir }}/kubeadm-client.conf"
+    src: "kubeadm-client.conf.{{ kubeadmConfig_api_version }}.j2"
+    dest: "{{ kube_config_dir }}/kubeadm-client.{{ kubeadmConfig_api_version }}.conf"
     backup: yes
   when: not is_kube_master
   vars:
     kubeadm_token: "{{ temp_token.stdout }}"
-  register: kubeadm_client_conf
 
 - name: Join to cluster if needed
   command: >-
     {{ bin_dir }}/kubeadm join
-    --config {{ kube_config_dir}}/kubeadm-client.conf
+    --config {{ kube_config_dir}}/kubeadm-client.{{ kubeadmConfig_api_version }}.conf
     --ignore-preflight-errors=all
   register: kubeadm_join
-  when: not is_kube_master and (kubeadm_client_conf.changed or not kubelet_conf.stat.exists)
+  when: not is_kube_master and (not kubelet_conf.stat.exists)
 
 - name: Wait for kubelet bootstrap to create config
   wait_for: