Use a variable for standardizing kubectl invocation (#8329)

* Add kubectl variable

* Replace kubectl usage by kubectl variable in roles

* Remove redundant --kubeconfig on kubectl usage

* Replace unecessary shell usage with command

roles/kubernetes/control-plane/tasks/kubeadm-setup.yml

@@ -190,7 +190,7 @@
 
 # FIXME(mattymo): from docs: If you don't want to taint your control-plane node, set this field to an empty slice, i.e. `taints: {}` in the YAML file.
 - name: kubeadm | Remove taint for master with node role
-  command: "{{ bin_dir }}/kubectl --kubeconfig {{ kube_config_dir }}/admin.conf taint node {{ inventory_hostname }} {{ item }}"
+  command: "{{ kubectl }} taint node {{ inventory_hostname }} {{ item }}"
   delegate_to: "{{ first_kube_control_plane }}"
   with_items:
     - "node-role.kubernetes.io/master:NoSchedule-"

roles/kubernetes/control-plane/tasks/kubeadm-upgrade.yml

@@ -61,8 +61,7 @@
 # FIXME: https://github.com/kubernetes/kubeadm/issues/1318
 - name: kubeadm | scale down coredns replicas to 0 if not using coredns dns_mode
   command: >-
-    {{ bin_dir }}/kubectl
-    --kubeconfig {{ kube_config_dir }}/admin.conf
+    {{ kubectl }}
     -n kube-system
     scale deployment/coredns --replicas 0
   register: scale_down_coredns

roles/kubernetes/kubeadm/tasks/main.yml

@@ -115,9 +115,9 @@
 #                 incorrectly to first master, creating SPoF.
 - name: Update server field in kube-proxy kubeconfig
   shell: >-
-    set -o pipefail && {{ bin_dir }}/kubectl --kubeconfig {{ kube_config_dir }}/admin.conf get configmap kube-proxy -n kube-system -o yaml
+    set -o pipefail && {{ kubectl }} get configmap kube-proxy -n kube-system -o yaml
     | sed 's#server:.*#server: https://127.0.0.1:{{ kube_apiserver_port }}#g'
-    | {{ bin_dir }}/kubectl --kubeconfig {{ kube_config_dir }}/admin.conf replace -f -
+    | {{ kubectl }} replace -f -
   args:
     executable: /bin/bash
   run_once: true
@@ -139,7 +139,7 @@
     mode: "0644"
 
 - name: Restart all kube-proxy pods to ensure that they load the new configmap
-  command: "{{ bin_dir }}/kubectl --kubeconfig {{ kube_config_dir }}/admin.conf delete pod -n kube-system -l k8s-app=kube-proxy --force --grace-period=0"
+  command: "{{ kubectl }} delete pod -n kube-system -l k8s-app=kube-proxy --force --grace-period=0"
   run_once: true
   delegate_to: "{{ groups['kube_control_plane']|first }}"
   delegate_facts: false

roles/kubernetes/node-label/tasks/main.yml

@@ -42,7 +42,7 @@
 
 - name: Set label to node
   command: >-
-      {{ bin_dir }}/kubectl label node {{ kube_override_hostname | default(inventory_hostname) }} {{ item }} --overwrite=true
+      {{ kubectl }} label node {{ kube_override_hostname | default(inventory_hostname) }} {{ item }} --overwrite=true
   loop: "{{ role_node_labels + inventory_node_labels }}"
   delegate_to: "{{ groups['kube_control_plane'][0] }}"
   changed_when: false