Kubernetes DNS服务配置案例

首先创建DNS服务的RC配置文件skydns-rc.yaml

apiVersion: v1
kind: ReplicationController
metadata:
  name: kube-dns-v8
  namespace: kube-system
  labels:
    k8s-app: kube-dns
    version: v8
    kubernetes.io/cluster-service: "true"
spec:
  replicas: 1
  selector:
    k8s-app: kube-dns
    version: v8
  template:
    metadata:
      labels:
        k8s-app: kube-dns
        version: v8
        kubernetes.io/cluster-service: "true"
    spec:
      containers:
      - name: etcd
        image: googlecontainer/etcd:2.0.9
        resources:
          limits:
            cpu: 100m
            memory: 50Mi
        command:
        - /usr/local/bin/etcd
        - -data-dir
        - /var/etcd/data
        - -listen-client-urls
        - http://127.0.0.1:2379,http://127.0.0.1:4001
        - -advertise-client-urls
        - http://127.0.0.1:2379,http://127.0.0.1:4001
        - -initial-cluster-token
        - skydns-etcd
        volumeMounts:
        - name: etcd-storage
          mountPath: /var/etcd/data
      - name: kube2sky
        image: googlecontainer/kube2sky:1.11
        resources:
          limits:
            cpu: 100m
            memory: 50Mi
        args:
        # command = "/kube2sky"
        - --kube_master_url=http://39.108.97.109:8080 #根据实际修改
        - -domain=cluster.local
      - name: skydns
        image: googlecontainer/skydns:2015-03-11-001
        resources:
          limits:
            cpu: 100m
            memory: 50Mi
        args:
        # command = "/skydns"
        - -machines=http://localhost:4001
        - -addr=0.0.0.0:53
        - -domain=cluster.local
        ports:
        - containerPort: 53
          name: dns
          protocol: UDP
        - containerPort: 53
          name: dns-tcp
          protocol: TCP
        livenessProbe:
          httpGet:
            path: /healthz
            port: 8080
            scheme: HTTP
          initialDelaySeconds: 30
          timeoutSeconds: 5
      volumes:
      - name: etcd-storage
        emptyDir: {}
      dnsPolicy: Default # Don't use cluster DNS.

 创建DNS服务的Service配置文件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:  10.254.0.100 #根据实际修改
  ports:
  - name: dns
    port: 53
    protocol: UDP
  - name: dns-tcp
    port: 53
    protocol: TCP

创建RC和Service，然后修改每台Node上Kubelet的启动参数，配置文件/etc/kubernetes/kubelet，修改后重启Kubelet。--resolv-conf=''不继承宿主机/etc/resolv.conf配置。

--cluster_dns=10.254.0.100
--cluster_domain=cluster.local
--resolv-conf=''

创建Pod busybox.yaml 用于测试DNS解释是否成功

apiVersion: v1
kind: Pod
metadata:
  name: busybox
spec:
  containers:
  - image: googlecontainer/busybox
    command:
      - sleep
      - "3600"
    imagePullPolicy: IfNotPresent
    name: busybox
  restartPolicy: Always

测试命令和结果

# kubectl exec busybox -- nslookup mysql
Server:    10.254.0.100
Address 1: 10.254.0.100

Name:      mysql
Address 1: 10.254.67.179

参考资料

https://github.com/kubernetes/kubernetes/blob/v1.0.1/cluster/addons/dns/skydns-rc.yaml.in

Customizing DNS Service

DNS for Services and Pods