本文基于kubernetes 1.5.2版本编写

在kubernetes1.2之前，采用skydns+kube2dns+etcd的方式来部署dns。而从1.3开始，则部署方式有了一点儿变化，将skydns和kube2dns封装到了一个容器镜像中，放弃了etcd，而将dns解析直接放入到了内存之中，同时引入了dnsmasq，进一步利用其缓存。

使用DaemonSet方式部署，在每台宿主机上均有一个DNS服务。

使用http方式访问api server

cat skydns-rc.yaml

apiVersion: extensions/v1beta1

kind: DaemonSet

metadata:

  name: kube-dns

  namespace: kube-system

  labels:

    k8s-app: kube-dns

    kubernetes.io/cluster-service: "true"

spec:

  template:

    metadata:

      labels:

        k8s-app: kube-dns

      annotations:

        scheduler.alpha.kubernetes.io/critical-pod: ''

        scheduler.alpha.kubernetes.io/tolerations: '[{"key":"CriticalAddonsOnly", "operator":"Exists"}]'

    spec:

      containers:

      - name: kubedns

        image: docker.io/googlecontainer/kubedns-amd64:1.9

        imagePullPolicy: IfNotPresent

        resources:

          limits:

            memory: 170Mi

          requests:

            cpu: 100m

            memory: 70Mi

        livenessProbe:

          httpGet:

            path: /healthz-kubedns

            port: 8080

            scheme: HTTP

          initialDelaySeconds: 60

          timeoutSeconds: 5

          successThreshold: 1

          failureThreshold: 5

        readinessProbe:

          httpGet:

            path: /readiness

            port: 8081

            scheme: HTTP

          initialDelaySeconds: 3

          timeoutSeconds: 5

        args:

        - --domain=lykops.net.

        #域名

        - --dns-port=10053

        - --config-map=kube-dns

        - --kube-master-url=http://192.168.20.128:8080

        - --v=0

        env:

        - name: PROMETHEUS_PORT

          value: "10055"

        ports:

        - containerPort: 10053

          name: dns-local

          protocol: UDP

        - containerPort: 10053

          name: dns-tcp-local

          protocol: TCP

        - containerPort: 10055

          name: metrics

          protocol: TCP

      - name: dnsmasq

        image: docker.io/googlecontainer/kube-dnsmasq-amd64:1.4.1

        imagePullPolicy: IfNotPresent

        livenessProbe:

          httpGet:

            path: /healthz-dnsmasq

            port: 8080

            scheme: HTTP

          initialDelaySeconds: 60

          timeoutSeconds: 5

          successThreshold: 1

          failureThreshold: 5

        args:

        - --cache-size=1000

        - --no-resolv

        - --server=127.0.0.1#10053

        ports:

        - containerPort: 53

          name: dns

          protocol: UDP

        - containerPort: 53

          name: dns-tcp

          protocol: TCP

        resources:

          requests:

            cpu: 150m

            memory: 10Mi

      - name: dnsmasq-metrics

        image:  docker.io/googlecontainer/dnsmasq-metrics-amd64:1.0.1

        imagePullPolicy: IfNotPresent

        livenessProbe:

          httpGet:

            path: /metrics

            port: 10054

            scheme: HTTP

          initialDelaySeconds: 60

          timeoutSeconds: 5

          successThreshold: 1

          failureThreshold: 5

        args:

        - --v=2

        - --logtostderr

        ports:

        - containerPort: 10054

          name: metrics

          protocol: TCP

        resources:

          requests:

            memory: 10Mi

      - name: healthz

        image: docker.io/googlecontainer/exechealthz-amd64:1.2

        imagePullPolicy: IfNotPresent

        resources:

          limits:

            memory: 50Mi

          requests:

            cpu: 10m

            memory: 50Mi

        args:

        - --cmd=nslookup kubernetes.default.svc.lykops.net 127.0.0.1 >/dev/null

        - --url=/healthz-dnsmasq

        - --cmd=nslookup kubernetes.default.svc.lykops.net 127.0.0.1:10053 >/dev/null

        - --url=/healthz-kubedns

        - --port=8080

        - --quiet

        ports:

        - containerPort: 8080

          protocol: TCP

      dnsPolicy: Default

kubectl create -f skydns-rc.yaml

使用https方式访问apiserver接口

cat skydns-rc.yaml

......

        args:

        - --domain=lykops.net.

        - --dns-port=10053

        - --config-map=kube-dns

        - --kube-master-url=https://192.168.20.128:6443

        #这里修改为https

        - --kubecfg-file=/etc/kubernetes/kubelet-config

        #添加认证信息配置文件

        - --v=0

        #挂载认证需要的信息配置文件和证书

        volumeMounts:

        - name: config

          mountPath: /etc/kubernetes/kubelet-config

          readOnly: True

        - name: certs

          mountPath: /etc/ssl/kube

          readOnly: True

        env:

        - name: PROMETHEUS_PORT

          value: "10055"

      .......

      #挂载宿主机的信息配置文件和证书

      volumes:

      - name: certs

        hostPath:

          path: /etc/ssl/kube

      - name: config

        hostPath:

          path: /etc/kubernetes/kubelet-config

      dnsPolicy: Default

kubectl create -f skydns-rc.yaml

配置service

cat skydns-svc.yaml

apiVersion: v1

kind: Service

metadata:

  name: kube-dns

  namespace: kube-system

  labels:

    k8s-app: kube-dns

    kubernetes.io/cluster-service: "true"

    kubernetes.io/name: "KubeDNS"

spec:

  selector:

    k8s-app: kube-dns

  clusterIP: 172.17.114.114

  #固定IP地址

  ports:

  - name: dns

    port: 53

    protocol: UDP

  - name: dns-tcp

    port: 53

protocol: TCP

kubectl create -f skydns-svc.yaml

配置kubelet--实现服务发现

等待服务部署完成，在集群宿主机上执行telnet 172.17.114.114 53，能通表示部署完成

在客户端上执行修改/etc/kubernetes/kubelet

KUBELET_ARGS="--cluster-domain=lykops.net --cluster_dns=172.17.114.114"

重启服务

service kubelet restart