CoreDNS Caching Sidecar

dns-sidecar.yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: busybox
spec:
  replicas: 1
  selector:
    matchLabels:
      app: busybox
      version: v1
  template:
    metadata:
      labels:
        app: busybox
        version: v1
    spec:
      initContainers:
      - name: init-dns
        image: busybox
        imagePullPolicy: IfNotPresent
        command:
        - sh
        args:
        - -c
        - |
          sed 's/nameserver.*/nameserver 127.0.0.1/g' /etc/resolv.conf > /mnt/resolvconf/resolv.conf
          echo ".:53 {
            errors
            health
            forward . /etc/resolv.conf
            cache 300 {
              prefetch 1
            }
          }" > /etc/coredns/Corefile
        volumeMounts:
        - name: etc-resolvconf
          mountPath: /mnt/resolvconf
        - name: coredns-config
          mountPath: /etc/coredns
      containers:
      - name: busybox
        image: busybox
        imagePullPolicy: IfNotPresent
        command:
        - sh
        args:
        - -c
        - |
          while true; do
            sleep 1
          done
        volumeMounts:
        - name: etc-resolvconf
          mountPath: /etc/resolv.conf
          subPath: resolv.conf
      - name: coredns
        image: mcr.microsoft.com/oss/kubernetes/coredns:1.6.6
        imagePullPolicy: IfNotPresent
        args:
        - -conf
        - /etc/coredns/Corefile
        livenessProbe:
          failureThreshold: 5
          httpGet:
            path: /health
            port: 8080
            scheme: HTTP
          initialDelaySeconds: 60
          periodSeconds: 10
          successThreshold: 1
          timeoutSeconds: 5
        resources:
          limits:
            memory: 170Mi
          requests:
            cpu: 100m
            memory: 70Mi
        securityContext:
          allowPrivilegeEscalation: false
          capabilities:
            add:
            - NET_BIND_SERVICE
            drop:
            - all
          procMount: Default
          readOnlyRootFilesystem: true
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
        volumeMounts:
        - name: coredns-config
          mountPath: /etc/coredns
          readOnly: true
        - name: coredns-tmp
          mountPath: /tmp
      volumes:
      - name: coredns-config
        emptyDir: {}
      - name: coredns-tmp
        emptyDir: {}
      - name: etc-resolvconf
        emptyDir: {}