使用的文件
kubedns-cm.yaml kubedns-controller.yaml kubedns-sa.yaml kubedns-svc.yaml

cat > kubedns-cm.yaml << EOF
apiVersion: v1
kind: ConfigMap
metadata:
  name: kube-dns
  namespace: kube-system
  labels:
    addonmanager.kubernetes.io/mode: EnsureExists
EOF

cat > kubedns-controller.yaml << EOF
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: kube-dns
  namespace: kube-system
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
spec:
  strategy:
    rollingUpdate:
      maxSurge: 10%
      maxUnavailable: 0
  selector:
    matchLabels:
      k8s-app: kube-dns
  template:
    metadata:
      labels:
        k8s-app: kube-dns
      annotations:
        scheduler.alpha.kubernetes.io/critical-pod: ''
    spec:
      tolerations:
      - key: "CriticalAddonsOnly"
        operator: "Exists"
      volumes:
      - name: kube-dns-config
        configMap:
          name: kube-dns
          optional: true
      containers:
      - name: kubedns
        image: xuejipeng/k8s-dns-kube-dns-amd64:v1.14.1
        resources:
          limits:
            memory: 170Mi
          requests:
            cpu: 100m
            memory: 70Mi
        livenessProbe:
          httpGet:
            path: /healthcheck/kubedns
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        readinessProbe:
          httpGet:
            path: /readiness
            port: 8081
            scheme: HTTP
          initialDelaySeconds: 3
          timeoutSeconds: 5
        args:
        - --domain=cluster.local.
        - --dns-port=10053
        - --config-dir=/kube-dns-config
        - --v=2
        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
        volumeMounts:
        - name: kube-dns-config
          mountPath: /kube-dns-config
      - name: dnsmasq
        image: xuejipeng/k8s-dns-dnsmasq-nanny-amd64:v1.14.1
        livenessProbe:
          httpGet:
            path: /healthcheck/dnsmasq
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - -v=2
        - -logtostderr
        - -configDir=/etc/k8s/dns/dnsmasq-nanny
        - -restartDnsmasq=true
        - --
        - -k
        - --cache-size=1000
        - --log-facility=-
        - --server=/cluster.local./127.0.0.1#10053
        - --server=/in-addr.arpa/127.0.0.1#10053
        - --server=/ip6.arpa/127.0.0.1#10053
        ports:
        - containerPort: 53
          name: dns
          protocol: UDP
        - containerPort: 53
          name: dns-tcp
          protocol: TCP
        resources:
          requests:
            cpu: 150m
            memory: 20Mi
        volumeMounts:
        - name: kube-dns-config
          mountPath: /etc/k8s/dns/dnsmasq-nanny
      - name: sidecar
        image: xuejipeng/k8s-dns-sidecar-amd64:v1.14.1
        livenessProbe:
          httpGet:
            path: /metrics
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - --v=2
        - --logtostderr
        - --probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.cluster.local.,5,A
        - --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local.,5,A
        ports:
        - containerPort: 10054
          name: metrics
          protocol: TCP
        resources:
          requests:
            memory: 20Mi
            cpu: 10m
      dnsPolicy: Default 
      serviceAccountName: kube-dns
EOF

cat > kubedns-sa.yaml << EOF
apiVersion: v1
kind: ServiceAccount
metadata:
  name: kube-dns
  namespace: kube-system
  labels:
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
EOF

cat > kubedns-svc.yaml <<EOF
apiVersion: v1
kind: Service
metadata:
  name: kube-dns
  namespace: kube-system
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
    kubernetes.io/name: "KubeDNS"
spec:
  selector:
    k8s-app: kube-dns
  clusterIP: 10.254.0.2
  ports:
  - name: dns
    port: 53
    protocol: UDP
  - name: dns-tcp
    port: 53
    protocol: TCP
EOF

具体的内容大家有兴趣的话可以细看配置文件，大概就是将服务间进行关联，从而实现dns解析。

检查 kubedns 功能
新建一个 Deployment

$ cat  my-nginx.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: my-nginx
spec:
  replicas: 2
  template:
    metadata:
      labels:
        run: my-nginx
    spec:
      containers:
      - name: my-nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80
$ kubectl create -f my-nginx.yaml

Export 该 Deployment, 生成 my-nginx 服务

$ kubectl expose deploy my-nginx
$ kubectl get services --all-namespaces |grep my-nginx
default       my-nginx     10.254.210.204   <none>        80/TCP          1h

创建另一个 Pod，查看 /etc/resolv.conf 是否包含 kubelet 配置的 –cluster-dns 和 –cluster-domain，是否能够将服务 my-nginx 解析到上面显示的 Cluster IP 10.254.210.204

$ cat pod-nginx.yaml
apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  containers:
  - name: nginx
    image: nginx:1.7.9
    ports:
    - containerPort: 80

$ kubectl create -f pod-nginx.yaml
$ kubectl exec  nginx -i -t -- /bin/bash

root@nginx:/# cat /etc/resolv.conf
nameserver 10.254.0.2
search default.svc.cluster.local svc.cluster.local cluster.local tjwq01.ksyun.com
options ndots:5

root@nginx:/# ping my-nginx
PING my-nginx.default.svc.cluster.local (10.254.210.204): 48 data bytes
^C--- my-nginx.default.svc.cluster.local ping statistics ---
2 packets transmitted, 0 packets received, 100% packet loss

root@nginx:/# ping kubernetes
PING kubernetes.default.svc.cluster.local (10.254.0.1): 48 data bytes
^C--- kubernetes.default.svc.cluster.local ping statistics ---
1 packets transmitted, 0 packets received, 100% packet loss

root@nginx:/# ping kube-dns.kube-system.svc.cluster.local
PING kube-dns.kube-system.svc.cluster.local (10.254.0.2): 48 data bytes
^C--- kube-dns.kube-system.svc.cluster.local ping statistics ---
1 packets transmitted, 0 packets received, 100% packet loss

如果dns无法做到正常解析（unknow host）等错误时，请检查selinux和防火墙策略。
确保执行过
iptables -P FORWARD ACCEPT
setenforce 0