running on the first master only.

roles/kubernetes-apps/metrics/tasks/main.yml

 ---
 - name: Metrics | Make sure Helm is installed
   command: "{{ bin_dir }}/helm version"
+  when:
+    - inventory_hostname == groups['kube-master'][0]
 
 - name: Metrics | Add coreos repo
   command: "{{ bin_dir }}/helm repo add coreos https://s3-eu-west-1.amazonaws.com/coreos-charts/stable/"
+  when:
+    - inventory_hostname == groups['kube-master'][0]
   run_once: true
 
 - name: Metrics | Install Prometheus Operator
   command: "{{ bin_dir }}/helm upgrade --install prometheus-operator coreos/prometheus-operator --namespace {{ monitoring_namespace }}"
-  when: prometheus_operator_enabled
+  when:
+    - prometheus_operator_enabled
+    - inventory_hostname == groups['kube-master'][0]
   run_once: true
 
 - name: Metrics | Install K8s cluster metrics
   command: "{{ bin_dir }}/helm upgrade --install kube-prometheus     coreos/kube-prometheus     --namespace {{ monitoring_namespace }}"
-  when: k8s_metrics_enabled
+  when: 
+    - k8s_metrics_enabled
+    - inventory_hostname == groups['kube-master'][0]
   run_once: true