apiVersion: v1
kind: ConfigMap
metadata:
  name: coredns-external
  namespace: kube-system
data:
  Corefile: |-
    lb.homelab.lumpiasty.xyz.:53 {
        view externalv4 {
            expr type() in ['A'] 
            expr not hasSuffix(name(), '.in-addr.arpa.')
        }
        log . {
            class all
        }
        template IN A {
          answer "{{ .Name }} 60 IN A 139.28.40.212"
        }
    }
    .:53 {
        # Filter out anything IPv4 related
        view external {
            expr type() in ['AAAA', 'SRV', 'PTR'] 
            expr not hasSuffix(name(), '.in-addr.arpa.')
        }
        errors
        health {
            lameduck 5s
        }
        ready
        log . {
            class error
        }
        # Exposes kubernetes domain names under homelab.lumpiasty.xyz
        # https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/
        kubernetes homelab.lumpiasty.xyz ip6.arpa {
            pods insecure
            endpoint_pod_names
            ttl 30
        }
        # Exposes loadbalancer domain names under lb.homelab.lumpiasty.xyz
        k8s_external lb.homelab.lumpiasty.xyz {
            ttl 30
        }
        # Cache results to reduce stress on apiserver
        cache 30 {
            disable success homelab.lumpiasty.xyz
            disable denial homelab.lumpiasty.xyz
        }
        reload
        loadbalance
    }
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    k8s-app: kube-dns-external
    kubernetes.io/name: CoreDNS
  name: coredns-external
  namespace: kube-system
spec:
  progressDeadlineSeconds: 600
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      k8s-app: kube-dns-external
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 1
    type: RollingUpdate
  template:
    metadata:
      labels:
        k8s-app: kube-dns-external
    spec:
      subdomain: kube-dns-external
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
            - podAffinityTerm:
                labelSelector:
                  matchExpressions:
                    - key: k8s-app
                      operator: In
                      values:
                        - kube-dns
                topologyKey: kubernetes.io/hostname
              weight: 100
      containers:
        - args:
            - -conf
            - /etc/coredns/Corefile
          env:
            - name: GOMEMLIMIT
              value: 161MiB
          image: registry.k8s.io/coredns/coredns:v1.12.0
          imagePullPolicy: IfNotPresent
          livenessProbe:
            failureThreshold: 5
            httpGet:
              path: /health
              port: 8080
              scheme: HTTP
            initialDelaySeconds: 60
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 5
          name: coredns
          ports:
            - containerPort: 53
              name: dns
              protocol: UDP
            - containerPort: 53
              name: dns-tcp
              protocol: TCP
            - containerPort: 9153
              name: metrics
              protocol: TCP
          readinessProbe:
            failureThreshold: 3
            httpGet:
              path: /ready
              port: 8181
              scheme: HTTP
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 1
          resources:
            limits:
              memory: 170Mi
            requests:
              cpu: 0
              memory: 70Mi
          securityContext:
            allowPrivilegeEscalation: false
            capabilities:
              add:
                - NET_BIND_SERVICE
              drop:
                - ALL
            readOnlyRootFilesystem: true
          volumeMounts:
            - mountPath: /etc/coredns
              name: config-volume
              readOnly: true
      dnsPolicy: Default
      nodeSelector:
        kubernetes.io/os: linux
      priorityClassName: system-cluster-critical
      restartPolicy: Always
      schedulerName: default-scheduler
      serviceAccount: coredns
      tolerations:
        - effect: NoSchedule
          key: node-role.kubernetes.io/control-plane
          operator: Exists
        - effect: NoSchedule
          key: node.cloudprovider.kubernetes.io/uninitialized
          operator: Exists
      volumes:
        - configMap:
            defaultMode: 420
            items:
              - key: Corefile
                path: Corefile
            name: coredns-external
          name: config-volume