K8S部署kubedns步骤

基础环境

基本的k8s集群，安装部署可参考我的文章。

部署kubedns步骤

1. 准备镜像

   # kingdragon 是我的docker hub仓库，你可以换成自己的仓库，并准备相应的镜像
   kingdragon/k8s-dns-dnsmasq-nanny-amd64:1.14.5
   kingdragon/k8s-dns-kube-dns-amd64:1.14.5
   kingdragon/k8s-dns-sidecar-amd64:1.14.5
   

2. 准备yaml文件

   • kubedns-cm.yaml

     apiVersion: v1
     kind: ConfigMap
     metadata:
       name: kube-dns
       namespace: kube-system
       labels:
         addonmanager.kubernetes.io/mode: EnsureExists
     

   • kubedns-controller.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: kingdragon/k8s-dns-kube-dns-amd64:1.14.5
             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
             #__PILLAR__FEDERATIONS__DOMAIN__MAP__
             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: kingdragon/k8s-dns-dnsmasq-nanny-amd64:1.14.5
             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
             # 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: kingdragon/k8s-dns-sidecar-amd64:1.14.5
             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  # Don't use cluster DNS.
           serviceAccountName: kube-dns
     

     补充：
     1、改镜像地址为你自己的镜像仓库。
     2、cluster.local.为集群的域名，参见你配置集群时的cluster.domin参数的值。

   • kubedns-sa.yaml

     apiVersion: v1
     kind: ServiceAccount
     metadata:
       name: kube-dns
       namespace: kube-system
       labels:
         kubernetes.io/cluster-service: "true"
         addonmanager.kubernetes.io/mode: Reconcile
     

   • kubedns-svc.yaml

     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
     

     补充：
     clusterIP: 10.254.0.2 即明确指定了 kube-dns Service IP，这个 IP 需要和 kubelet 的 --cluster-dns 参数值一致。

3. 部署kubedns

   # 路径可以不一样
   $ pwd
   /root/kubedns
   
   $ ls *.yaml
   kubedns-cm.yaml  kubedns-controller.yaml  kubedns-sa.yaml  kubedns-svc.yaml
   
   $ kubectl create -f .
   

4. 校验

   $ cat >> my-nginx.yaml << EOF
   apiVersion: extensions/v1beta1
   kind: Deployment
   metadata:
     name: my-nginx
   spec:
     replicas: 2
     template:
       metadata:
         labels:
           run: my-nginx
       spec:
         containers:
         - name: my-nginx
           image: harbor-001.jimmysong.io/library/nginx:1.9
           ports:
           - containerPort: 80
   EOF
   $ 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
   
   
   # 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 Cluster IP `10.254.179.239`。
   
   
   $ kubectl create -f nginx-pod.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. jimmysong.io
   options ndots:5
   
   root@nginx:/# ping my-nginx
   PING my-nginx.default.svc.cluster.local (10.254.179.239): 56 data bytes
   76 bytes from 119.147.223.109: Destination Net Unreachable
   ^C--- my-nginx.default.svc.cluster.local ping statistics ---
   
   root@nginx:/# ping kubernetes
   PING kubernetes.default.svc.cluster.local (10.254.0.1): 56 data bytes
   ^C--- kubernetes.default.svc.cluster.local ping statistics ---
   11 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): 56 data bytes
   ^C--- kube-dns.kube-system.svc.cluster.local ping statistics ---
   6 packets transmitted, 0 packets received, 100% packet loss