五、搭建kube-dns

2022-12-29 20:33:15

1. 简介

kube-dns用来为kubernetes service分配子域名，在集群中可以通过名称访问service。通常kube-dns会为service赋予一个名为“service名称.namespace.svc.cluster.local”的A记录，用来解析service的cluster ip。

2.修改Node配置文件

2.1 修改kubelet配置文件

vim /etc/kubernetes/kubelet

KUBELET_ADDRESS="--address=0.0.0.0"

#KUBELET_HOSTNAME="--hostname-override=127.0.0.1"

KUBELET_HOSTNAME="--hostname-override=k8s-node-1"

KUBELET_API_SERVER="--api-servers=http://k8s-master:8080"

KUBELET_POD_INFRA_CONTAINER="--pod-infra-container-image=registry.access.redhat.com/rhel7/pod-infrastructure:latest"

KUBELET_ARGS="--cluster-dns=172.16.1.100 --cluster-domain=cluster.local. --allow-privileged=true"    #设置dns ip

2.2 重启kubelet服务

systemctl restart kubelet.service

3.创建kube-dns所需配置文件

3.1 创建kube-dns-rc文件

vim kube-dns-rc.yaml

apiVersion: v1

kind: ReplicationController

metadata:

  name: kube-dns-v20

  namespace: kube-system

  labels:

    k8s-app: kube-dns

    version: v20

    kubernetes.io/cluster-service: "true"

spec:

  replicas: 1

  selector:

    k8s-app: kube-dns

    version: v20

  template:

    metadata:

      labels:

        k8s-app: kube-dns

        version: v20

      annotations:

        scheduler.alpha.kubernetes.io/critical-pod: ''

        scheduler.alpha.kubernetes.io/tolerations: '[{"key":"CriticalAddonsOnly", "operator":"Exists"}]'

    spec:

      containers:

      - name: kubedns

        image: gcr.io/google_containers/kubedns-amd64:1.8

        imagePullPolicy: IfNotPresent

        resources:

          limits:

            memory: 170Mi

          requests:

            cpu: 100m

            memory: 70Mi

        livenessProbe:

          httpGet:

            path: /healthz-kubedns

            port: 8080

            scheme: HTTP

          initialDelaySeconds: 60

          timeoutSeconds: 5

          successThreshold: 1

          failureThreshold: 5

        readinessProbe:

          httpGet:

            path: /readiness

            port: 8081

            scheme: HTTP

          initialDelaySeconds: 3

          timeoutSeconds: 5

        args:

        - --domain=cluster.local.

        - --dns-port=10053

        - --kube-master-url=http://10.0.251.148:8080

        ports:

        - containerPort: 10053

          name: dns-local

          protocol: UDP

        - containerPort: 10053

          name: dns-tcp-local

          protocol: TCP

      - name: dnsmasq

        image: gcr.io/google_containers/kube-dnsmasq-amd64:1.4.1

        imagePullPolicy: IfNotPresent

        livenessProbe:

          httpGet:

            path: /healthz-dnsmasq

            port: 8080

            scheme: HTTP

          initialDelaySeconds: 60

          timeoutSeconds: 5

          successThreshold: 1

          failureThreshold: 5

        args:

        - --cache-size=1000

        - --no-resolv

        - --server=127.0.0.1#10053

        - --log-facility=-

        ports:

        - containerPort: 53

          name: dns

          protocol: UDP

        - containerPort: 53

          name: dns-tcp

          protocol: TCP

      - name: healthz

        image: gcr.io/google_containers/exechealthz-amd64:1.2

        imagePullPolicy: IfNotPresent

        resources:

          limits:

            memory: 50Mi

          requests:

            cpu: 10m

            memory: 50Mi

        args:

        - --cmd=nslookup kubernetes.default.svc.cluster.local. 127.0.0.1 >/dev/null

        - --url=/healthz-dnsmasq

        - --cmd=nslookup kubernetes.default.svc.cluster.local. 127.0.0.1:10053 >/dev/null

        - --url=/healthz-kubedns

        - --port=8080

        - --quiet

        ports:

        - containerPort: 8080

          protocol: TCP

      dnsPolicy: Default

此rc配置文件需要确定的是Kubernetes Master地址填写正确，以及image可以正常pull使用。

3.2 创建kube-dns-svc.yaml

vim kube-dns-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: 172.16.1.100    #设置dns服务地址

  ports:

  - name: dns

    port: 53

    protocol: UDP

  - name: dns-tcp

    port: 53

    protocol: TCP

3.3 下载docker镜像

docker pull gcr.io/google_containers/kubedns-amd64:1.8

docker pull gcr.io/google_containers/kube-dnsmasq-amd64:1.4.1

docker pull gcr.io/google_containers/exechealthz-amd64:1.2

在所有Node上准备好所需镜像，可以提升Kubernetes创建Pod的速度。

3.4 启动RC和SVC

kubectl create -f kube-dns-rc.yaml

kubectl create -f kube-dns-svc.yaml

3.5 验证dns-pod启动是否成功

kubectl get -o wide

&验证kube-dns pod启动没问题后，kube-dns及可使用。至此Kubernetes环境构建完成，可以先上使用，接下来就需要我们自己编写配置文件了。

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