参考文档：
Kube-DNS在集群范围内完成服务名到ClusterIP的解析，对服务进行访问，提供了服务发现机制的基本功能。
1. 基础环境
Kubernetes支持kube-dns以Cluster Add-On的形式运行。Kubernetes会在集群中调度一个DNS的Pod与Service。
1. 准备images
kubernetes部署Pod服务时，为避免部署时发生pull镜像超时的问题，建议提前将相关镜像pull到相关所有节点（实验），或搭建本地镜像系统。
2. 下载kube-dns范本
3. 配置kube-dns Service
4. 配置kube-dns ServiceAccount
5. 配置kube-dns ConfigMap
ConfigMap的典型用法是：
验证kube-dns功能不需要做修改，如果需要自定义DNS与上游DNS服务器，可对ConfigMap进行修改，见第四章节。
6. 配置kube-dns Deployment
# 第97，148，187行的三个容器的启动镜像； # 第127，168,200，201行的域名，域名同kubelet启动参数中的”--cluster-domain”对应，注意域名”cluster.local.”后的“.” [root@kubenode1 kubedns]# vim kube-dns.yaml 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: # replicas: not specified here: # 1. In order to make Addon Manager do not reconcile this replicas parameter. # 2. Default is 1. # 3. Will be tuned in real time if DNS horizontal auto-scaling is turned on. 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: netonline/k8s-dns-kube-dns-amd64:1.14.8 resources: # TODO: Set memory limits when we've profiled the container for large # clusters, then set request = limit to keep this container in # guaranteed class. Currently, this container falls into the # "burstable" category so the kubelet doesn't backoff from restarting it. 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 # we poll on pod startup for the Kubernetes master service and # only setup the /readiness HTTP server once that's available. 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: netonline/k8s-dns-dnsmasq-nanny-amd64:1.14.8 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 - --no-negcache - --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 # see: https://github.com/kubernetes/kubernetes/issues/29055 for details resources: requests: cpu: 150m memory: 20Mi volumeMounts: - name: kube-dns-config mountPath: /etc/k8s/dns/dnsmasq-nanny - name: sidecar image: netonline/k8s-dns-sidecar-amd64:1.14.8 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,SRV - --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local.,5,SRV ports: - containerPort: 10054 name: metrics protocol: TCP resources: requests: memory: 20Mi cpu: 10m dnsPolicy: Default # Don't use cluster DNS. serviceAccountName: kube-dns
7. 启动kube-dns
1. kube-dns Deployment&Service&Pod
2. kube-dns 查询
从kubernetes v1.6开始，用户可以在集群内配置私有DNS区域（一般称为存根域Stub Domain）与外部上游域名服务。
1. 原理
2. 自定义DNS方式
3. 重建kube-dns ConfigMap
4. 自定义dns服务器
5. 启动Pod
6. 验证自定义的DNS配置
观察stub domain 172.20.1.201上dnsmasq服务的输出：kube节点172.30.200.23（Pod所在的节点，flannel网络，snat出节点）对server.out.kubenetes的查询，dnsmasq返回预定义的主机地址。
原文链接：https://www.cnblogs.com/netonline/p/8858809.html
原创文章，作者：优速盾-小U，如若转载，请注明出处：https://www.cdnb.net/bbs/archives/22651
