在之前几篇文章的基础，（Centos7部署Kubernetes集群、基于kubernetes集群部署DashBoard、为Kubernetes集群部署本地镜像仓库），本文继续搭建Kubernete中的服务注册发现机制——SkyDNS.
kubernetes可以为pod提供dns（skyDNS）内部域名解析服务。其主要作用是为pod提供可以直接通过service的名字解析为对应service的ip的功能。skyDNS由三部分组成：kube2sky、etcd、skydns。
kube2sky的功能是监测api-server中的service的变化，当service创建、删除、修改时，获取对应的service信息，将其保存在etcd的中；
Etcd的功能是存储kube2sky保存过来的数据；
Skydns。在kubelet创建pod时，会使用为kubelet配置的“KUBELET_ARGS="--cluster-dns=10.254.10.2 --cluster-domain=sky --allow-privileged=true"” 在创建的pod中从而使用对应的dns服务器。而这一dns解析服务，实际是由Skydns提供的。
[root@k8s-master ~]# etcdctl mk /skydns/config ‘{"dns-addr":"10.254.10.2:53","ttl":3600,"domain":"sky."}‘ {"dns-addr":"10.254.10.2:53","ttl":3600,"domain":"sky."}
在每个node中更改kubelet的配置文件如下红色部分，更改完成之后重启服务。
[root@K8s-node-1 ~]# vim /etc/kubernetes/kubelet ### # kubernetes kubelet (minion) config # The address for the info server to serve on (set to 0.0.0.0 or "" for all interfaces) KUBELET_ADDRESS="--address=0.0.0.0" # The port for the info server to serve on # KUBELET_PORT="--port=10250" # You may leave this blank to use the actual hostname #KUBELET_HOSTNAME="--hostname-override=127.0.0.1" KUBELET_HOSTNAME="--hostname-override=k8s-node-1" # location of the api-server KUBELET_API_SERVER="--api-servers=http://k8s-master:8080" # pod infrastructure container KUBELET_POD_INFRA_CONTAINER="--pod-infra-container-image=registry.access.redhat.com/rhel7/pod-infrastructure:latest" # Add your own! KUBELET_ARGS="--cluster-dns=10.254.10.2 --cluster-domain=sky --allow-privileged=true" [root@k8s-node-1 ~]# systemctl restart kubelet.service
编辑skydns_dpm.yaml文件，更改以下红色部分（拷贝到机器上之后，最好把中文注释去掉）：
apiVersion: extensions/v1beta1 kind: Deployment metadata: name: kube-dns namespace: kube-system spec: replicas: 1 template: metadata: labels: name: kube-dns tier: platform subsystem: unconfirmed k8s-app: kube-dns version: v9 partition: "no" kubernetes.io/cluster-service: "true" spec: containers: - name: kube2sky #填写你自己的镜像名称 image: gcr.io/google_containers/kube2sky:1.11 resources: limits: cpu: 100m memory: 50Mi args: # 同etcd中配置的/skydns/config中的domain名 - -domain=sky # master地址 - --kube_master_url=http://10.0.251.148:8080 # etcd地址 - -etcd-server=http://10.0.251.148:2379 - name: skydns #你的镜像名称 image: gcr.io/google_containers/skydns:2015-10-13-8c72f8c resources: limits: cpu: 100m memory: 50Mi args: # command = "/skydns" # etcd地址 - -machines=http://10.0.251.148:2379 - -addr=0.0.0.0:53 - -ns-rotate=false #同etcd中配置的/skydns/config中的domain名，最后有‘点’ - -domain=sky. ports: - containerPort: 53 name: dns protocol: UDP - containerPort: 53 name: dns-tcp protocol: TCP dnsPolicy: Default # Don‘t use cluster DNS.
编辑skydns-svc.yaml文件，更改以下红色部分:
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: 10.254.10.2 ports: - name: dns port: 53 protocol: UDP - name: dns-tcp port: 53 protocol: TCP
在master执行如下命令：
kubectl create -f skydns_dpm.yaml
kubectl create -f skydns-svc.yaml
之后，dns搭建完成。
[root@k8s-master yaml]# kubectl get deployment --all-namespaces NAMESPACE NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE kube-system kube-dns 1 1 1 1 2m kube-system kubernetes-dashboard-latest 1 1 1 1 1d [root@k8s-master yaml]# kubectl get pod -o wide --all-namespaces NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE kube-system kube-dns-520758324-1luff 2/2 Running 0 2m 10.0.28.2 k8s-node-1 kube-system kubernetes-dashboard-latest-127826951-pxrpk 1/1 Running 0 1d 10.0.62.2 k8s-node-2
[root@k8s-master yaml]# cat test_svc.yml apiVersion: v1 kind: Service metadata: labels: name: mysql role: service name: mysql-service spec: ports: - port: 3306 targetPort: 3306 type: NodePort selector: name: mysql [root@k8s-master yaml]# kubectl create -f test_svc.yml service "mysql-service" created [root@k8s-master yaml]# kubectl get service NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes 10.254.0.1 <none> 443/TCP 1d mysql-service 10.254.61.203 <nodes> 3306/TCP 6s
[root@k8s-master yaml]# cat busybox.yml apiVersion: v1 kind: Pod metadata: labels: name: busybox role: master name: busybox spec: containers: - name: busybox image: docker.io/busybox command: - sleep - "360000" [root@k8s-master yaml]# kubectl create -f busybox.yml pod "busybox" created [root@k8s-master yaml]# kubectl get pod -o wide --all-namespaces NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE default busybox 1/1 Running 0 18s 10.0.62.3 k8s-node-2 kube-system kube-dns-520758324-1luff 2/2 Running 0 33m 10.0.28.2 k8s-node-1 kube-system kubernetes-dashboard-latest-127826951-pxrpk 1/1 Running 0 1d 10.0.62.2 k8s-node-2
[root@k8s-master yaml]# kubectl exec -i -t busybox sh / # cat /etc/resolv.conf search default.svc.sky svc.sky sky openstacklocal nameserver 10.254.10.2 nameserver 10.0.251.90 nameserver 192.168.5.225 nameserver 192.168.5.226 options ndots:5 / # / # ping mysql-service PING mysql-service (10.254.61.203): 56 data bytes
原文：http://www.cnblogs.com/zhenyuyaodidiao/p/6500992.html