CoreDNS kubernetes 安装使用

kubernetes 以前是skydns 后面变为 dnsmasq,coredns 也是一个不错的工具

1. 准备环境

安装 kubernetes

配置 kubelet  的cluster-dns

2. 下载coredns kubernetes 模板

地址：https://github.com/coredns/deployment/tree/master/kubernetes

3. 配置生成 coredns 配置信息

参考github 文档

./deploy.sh 10.3.0.0/24 | kubectl apply -f -

kubectl delete --namespace=kube-system deployment kube-dns

参考配置：

apiVersion: v1

kind: ConfigMap

metadata:

  name: coredns

  namespace: kube-system

data:

  Corefile: |

    .:53 {

        errors

        log stdout

        health

        kubernetes cluster.local 10.254.0.0/16

        proxy . /etc/resolv.conf

        cache 30

    }

---

apiVersion: extensions/v1beta1

kind: Deployment

metadata:

  name: coredns

  namespace: kube-system

  labels:

    k8s-app: coredns

    kubernetes.io/cluster-service: "true"

    kubernetes.io/name: "CoreDNS"

spec:

  replicas: 1

  selector:

    matchLabels:

      k8s-app: coredns

  template:

    metadata:

      labels:

        k8s-app: coredns

      annotations:

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

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

    spec:

      containers:

      - name: coredns

        image: coredns/coredns:latest

        imagePullPolicy: Always

        args: [ "-conf", "/etc/coredns/Corefile" ]

        volumeMounts:

        - name: config-volume

          mountPath: /etc/coredns

        ports:

        - containerPort: 53

          name: dns

          protocol: UDP

        - containerPort: 53

          name: dns-tcp

          protocol: TCP

        livenessProbe:

          httpGet:

            path: /health

            port: 8080

            scheme: HTTP

          initialDelaySeconds: 60

          timeoutSeconds: 5

          successThreshold: 1

          failureThreshold: 5

      dnsPolicy: Default

      volumes:

        - name: config-volume

          configMap:

            name: coredns

            items:

            - key: Corefile

              path: Corefile

---

apiVersion: v1

kind: Service

metadata:

  name: kube-dns

  namespace: kube-system

  labels:

    k8s-app: coredns

    kubernetes.io/cluster-service: "true"

    kubernetes.io/name: "CoreDNS"

spec:

  selector:

    k8s-app: coredns

  clusterIP: 10.254.0.3

  ports:

  - name: dns

    port: 53

    protocol: UDP

  - name: dns-tcp

    port: 53

    protocol: TCP

4. 创建Deployment

kubectl apply -f dns.yaml

5. 总结

使用起来还是比较简单的，就一个容器镜像，同时扩展还是比较强大的

6. 测试

测试pod :

apiVersion: v1

kind: Pod

metadata:

  name: busybox

  namespace: default

spec:

  containers:

  - image: busybox

    command:

      - sleep

      - "3600"

    imagePullPolicy: IfNotPresent

    name: busybox

  restartPolicy: Always

 测试命令 nslookup

测试命令 nslookup

7. 参考文档

https://github.com/coredns/deployment/tree/master/kubernetes

https://coredns.io/

https://coredns.io/2017/05/08/custom-dns-entries-for-kubernetes/

Kubernetes

CoreDNS kubernetes 安装使用