标签：docker cmd always resources skydns com nes href doc
DNS (domain name system),提供域名解析服务，解决了难于记忆的IP地址问题，以更人性可读可记忆可标识的方式映射对应IP地址。
Cluster DNS扩展插件用于支持k8s集群系统中各服务之间发现与调用。
组件：
?SkyDNS 提供DNS解析服务
?Etcd 存储DNS信息
?Kube2sky 监听kubernetes，当有Service创建时，生成相应的记录到SkyDNS。
本文章的实验环境与《k8s入门系列之集群安装篇》介绍中一致。master(1) + node(4)
1.修改所有node的配置文件：/etc/kubernetes/kubelet
node1,node2,node3.node4:
[root@node1 ~]# tail -n 1 /etc/kubernetes/kubelet
KUBELET_ARGS="--cluster-dns=10.254.254.254 --cluster-domain=cluster.local"
2.所有node(node1,node2,node3,node4)重新启动kubelet服务
[root@node1 ~]# systemctl restart kubelet.service
3.根据namespace分为不同的名称空间，将系统服务统一放到一个单独的空间：kube-system，由于默认空间只有default，我们首先要创建kube-system空间。
[root@master skydns]# cat kube-system.yml
apiVersion: v1
kind: Namespace
metadata:
name: kub-system
4.在master服务器上编辑ReplicationController文件skydns-rc.yml
[root@master skydns]# cat skydns-rc.yml
apiVersion: v1 kind: ReplicationController metadata: name: kube-dns-v11 namespace: kube-system labels: k8s-app: kube-dns version: v11 kubernetes.io/cluster-service: "true" spec: replicas: 1 selector: k8s-app: kube-dns version: v11 template: metadata: labels: k8s-app: kube-dns version: v11 kubernetes.io/cluster-service: "true" spec: containers: - name: etcd image: docker.gaoxiaobang.com/kubernetes/etcd-amd64:2.2.1 resources: limits: cpu: 100m memory: 500Mi requests: 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: docker.gaoxiaobang.com/kubernetes/kube2sky:1.14 args: # command = "/kube2sky" - --domain=cluster.local - --kube-master-url=http://192.168.30.20:8080 resources: limits: cpu: 100m memory: 200Mi requests: cpu: 100m memory: 50Mi - name: skydns image: docker.gaoxiaobang.com/kubernetes/skydns:2015-10-13-8c72f8c resources: limits: cpu: 100m memory: 200Mi requests: cpu: 100m memory: 50Mi args: - -machines=http://127.0.0.1:4001 - -addr=0.0.0.0:53 - -ns-rotate=false - -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: 60 timeoutSeconds: 5 successThreshold: 1 failureThreshold: 5 readinessProbe: httpGet: path: /readiness port: 8080 scheme: HTTP initialDelaySeconds: 30 timeoutSeconds: 5 - name: healthz image: docker.gaoxiaobang.com/kubernetes/exechealthz:1.0 resources: limits: cpu: 10m memory: 20Mi requests: cpu: 10m memory: 20Mi args: - -cmd=nslookup kubernetes.default.svc.cluster.local localhost >/dev/null - -port=8080 ports: - containerPort: 8080 protocol: TCP volumes: - name: etcd-storage emptyDir: {} dnsPolicy: Default
5.在master上创建skydns服务文件skydns-svc.yml
[root@master skydns]# cat skydns-svc.yml
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: 10.254.254.254 ports: - name: dns port: 53 protocol: UDP - name: dns-tcp port: 53 protocol: TCP
6.在集群中创建cluster-dns解析应用
?创建Namespace
[root@master skydns]# kubectl create -f kube-system.yml
?创建ReplicationController
[root@master skydns]# kubectl create -f skydns-rc.yml
?创建Service
[root@master skydns]# kubectl create -f skydns-svc.yml
7.查看skydns-rc.yml文件中定义pod的启动状态，如下则启动成功。
[root@master skydns]# kubectl get pod --namespace=kube-system NAME READY STATUS RESTARTS AGE kube-dns-v11-ey14j 4/4 Running 8 1d
8.查看skydns-svc.yml文件中定义的Service的信息。
[root@master skydns]# kubectl get svc -l k8s-app=kube-dns --namespace=kube-system NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE kube-dns 10.254.254.254 <none> 53/UDP,53/TCP 1d
9.测试DNS的效果。
?部署一个busybox的Pod
[root@master test]# cat busybox.yml
apiVersion: v1 kind: Pod metadata: name: busybox namespace: default spec: containers: - image: busybox command: - sleep - "3600" imagePullPolicy: IfNotPresent name: busybox restartPolicy: Always
?验证kubernetes服务的地址解析，出现如下所示则证明DNS解析正常。
[root@master test]# kubectl exec busybox nslookup kubernetes Server: 10.254.254.254 Address 1: 10.254.254.254 Name: kubernetes Address 1: 10.254.0.1
*提示：kubernetes服务是kubernetes集群安装之后默认的一个服务。
标签：docker cmd always resources skydns com nes href doc
原文地址：http://www.cnblogs.com/xkops/p/6232392.html
