Add PodDisruptionBudget for CoreDNS deployment. Allows users to contr…

…ol disruption behavior and set maximum unavailable pods

roles/kubernetes-apps/ansible/defaults/main.yml

@@ -16,8 +16,14 @@ coredns_ordinal_suffix: ""
 coredns_deployment_nodeselector: "kubernetes.io/os: linux"
 coredns_default_zone_cache_block: |
   cache 30
+
 coredns_host_network: false
 coredns_port: 53
+
+coredns_pod_disruption_budget: false
+# value for coredns pdb
+coredns_pod_disruption_budget_max_unavailable: 1
+
 # coredns_additional_configs adds any extra configuration to coredns
 # coredns_additional_configs: |
 #   whoami

roles/kubernetes-apps/ansible/tasks/coredns.yml

@@ -33,12 +33,14 @@
     - { name: coredns, src: coredns-deployment.yml, file: coredns-deployment-secondary.yml, type: deployment }
     - { name: coredns, src: coredns-svc.yml, file: coredns-svc-secondary.yml, type: svc }
     - { name: dns-autoscaler, src: dns-autoscaler.yml, file: coredns-autoscaler-secondary.yml, type: deployment }
+    - { name: coredns, file: coredns-poddisruptionbudget.yml, type: poddisruptionbudget, when: "{{ coredns_pod_disruption_budget }}"}
   register: coredns_secondary_manifests
   vars:
     clusterIP: "{{ skydns_server_secondary }}"
     coredns_ordinal_suffix: "-secondary"
   when:
     - dns_mode == 'coredns_dual'
     - inventory_hostname == groups['kube_control_plane'][0]
+    - item.when | default(True) | bool
   tags:
     - coredns

roles/kubernetes-apps/ansible/templates/coredns-poddisruptionbudget.yml.j2

@@ -0,0 +1,11 @@
+{%- if coredns_pod_disruption_budget -%}
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: coredns{{ coredns_ordinal_suffix }}
+spec:
+  maxUnavailable: {{ coredns_pod_disruption_budget_max_unavailable }}
+  selector:
+    matchLabels:
+      k8s-app: kube-dns{{ coredns_ordinal_suffix }}
+{% endif %}