dynamic-dns-example.yaml

apiVersion: v1
kind: List
metadata:
  name: custom-dns
items:
  - apiVersion: v1
    kind: Namespace
    metadata:
      name: custom-dns
  - apiVersion: v1
    kind: ServiceAccount
    metadata:
      name: coredns
      namespace: custom-dns
  - apiVersion: rbac.authorization.k8s.io/v1
    kind: ClusterRoleBinding
    metadata:
      name: system:custom-dns:coredns
    roleRef:
      apiGroup: rbac.authorization.k8s.io
      kind: ClusterRole
      name: openshift-dns
    subjects:
      - kind: ServiceAccount
        name: coredns
        namespace: custom-dns
  - apiVersion: v1
    kind: Service
    metadata:
      name: coredns
      namespace: custom-dns
    spec:
      ports:
        - name: dns
          port: 53
          protocol: UDP
          targetPort: dns
        - name: dns-tcp
          port: 53
          protocol: TCP
          targetPort: dns-tcp
        - name: metrics
          port: 9153
          protocol: TCP
          targetPort: metrics
      selector:
        app: coredns
      sessionAffinity: None
      type: ClusterIP
  - apiVersion: v1
    kind: ConfigMap
    metadata:
      name: coredns
      namespace: custom-dns
    data:
      Corefile: |
        # Add your CoreDNS customizations as import files.
        # Refer to https://cloud.ibm.com/docs/containers?topic=containers-cluster_dns for details.
        .:5353 {
            errors
            health {
                lameduck 20s
            }
            rewrite name exact my-on-prem-application-17146.com my-on-prem-application-17146.custom-dns.svc.cluster.local 
            ready
            kubernetes cluster.local in-addr.arpa ip6.arpa {
                pods insecure
                fallthrough in-addr.arpa ip6.arpa
                ttl 120
            }
            prometheus :9153
            forward . /etc/resolv.conf {
                policy sequential
            }
            cache 900 {
                denial 9984 30
            }
            reload
        }
  - apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: coredns
      namespace: custom-dns
    spec:
      replicas: 1
      selector:
        matchLabels:
          app: coredns
      template:
        metadata:
          labels:
            app: coredns
        spec:
          serviceAccount: coredns
          affinity:
            podAntiAffinity:
              requiredDuringSchedulingIgnoredDuringExecution:
                - labelSelector:
                    matchExpressions:
                      - key: app
                        operator: In
                        values: [ "coredns" ]
                  topologyKey: "kubernetes.io/hostname"
              preferredDuringSchedulingIgnoredDuringExecution:
                - weight: 100
                  podAffinityTerm:
                    labelSelector:
                      matchExpressions:
                        - key: app
                          operator: In
                          values: [ "coredns" ]
                    topologyKey: topology.kubernetes.io/zone
          containers:
            - args:
                - -conf
                - /etc/coredns/Corefile
              command:
                - coredns
              image: quay.io/openshift-release-dev/ocp-v4.0-art-dev@sha256:f834b7db3bda6ee97c94869393c7a0dd24fec2bb3aba0f5c684bfaa1d7c28de3
              imagePullPolicy: IfNotPresent
              livenessProbe:
                failureThreshold: 5
                httpGet:
                  path: /health
                  port: 8080
                  scheme: HTTP
                initialDelaySeconds: 60
                periodSeconds: 10
                successThreshold: 1
                timeoutSeconds: 5
              name: dns
              ports:
                - containerPort: 5353
                  name: dns
                  protocol: UDP
                - containerPort: 5353
                  name: dns-tcp
                  protocol: TCP
              readinessProbe:
                failureThreshold: 3
                httpGet:
                  path: /ready
                  port: 8181
                  scheme: HTTP
                initialDelaySeconds: 10
                periodSeconds: 3
                successThreshold: 1
                timeoutSeconds: 3
              resources:
                requests:
                  cpu: 50m
                  memory: 70Mi
              terminationMessagePath: /dev/termination-log
              terminationMessagePolicy: FallbackToLogsOnError
              volumeMounts:
                - mountPath: /etc/coredns
                  name: config-volume
                  readOnly: true
          volumes:
            - name: config-volume
              configMap:
                defaultMode: 420
                name: coredns