Backport of fixes to release-2.8 for 2.8.1? (#3897)

* Fix assertion for alone etcd nodes (#3847)

* Fix error with ipvs on cluster reset task (#3848)

* Reset: Check for kube-ipvs0 presence before remove it (#3816)

roles/kubernetes/preinstall/tasks/0020-verify-settings.yml

@@ -109,7 +109,7 @@
 - name: Stop if RBAC and anonymous-auth are not enabled when insecure port is disabled
   assert:
     that: rbac_enabled and kube_api_anonymous_auth
-  when: kube_apiserver_insecure_port == 0
+  when: kube_apiserver_insecure_port == 0 and inventory_hostname in groups['kube-master']
   ignore_errors: "{{ ignore_assert_errors }}"
 
 - name: Stop if kernel version is too low

roles/reset/tasks/main.yml

@@ -110,12 +110,18 @@
 - name: Clear IPVS virtual server table
   shell: "ipvsadm -C"
   when:
-    - kube_proxy_mode == 'ipvs'
+    - kube_proxy_mode == 'ipvs' and inventory_hostname in groups['k8s-cluster']
+
+- name: reset | check kube-ipvs0 network device
+  stat:
+    path: /sys/class/net/kube-ipvs0
+  register: kube_ipvs0
 
 - name: reset | Remove kube-ipvs0
   command: "ip link del kube-ipvs0"
   when:
     - kube_proxy_mode == 'ipvs'
+    - kube_ipvs0.stat.exists
 
 - name: reset | delete some files and directories
   file: