二进制部署K8s集群第21节addons之安装部署coredns

二进制部署K8s集群第21节addons之安装部署coredns

一、k8s服务发现插件-CoreDNS

CoreDNS能够实现自动关联Service资源的 “名称” 和 ”集群网络IP“，从而达到服务被集群自动发现

操作过程

运维主机创建资源配置清单 下载coredns镜像上传到仓库 配置内网dns node主机应用资源配置清单

1.1 架构

1.2 部署k8s资源配置清单的内网> /etc/nginx/conf.d/k8s-yaml.od.com.conf << 'eof' server { listen 80; server_name k8s-yaml.od.com; location / { autoindex on; default_type text/plain; root /data/k8s-yaml; } } eof nginx -s reload

1.3 准备资源配置清单

rbac.yaml 基于角色访问控制资源配置清单 configmap.yaml 配置资源配置清单 deployment.yaml 控制器资源配置清单 svc.yaml service资源配置清单

资源清单下载地址：准备rbac.yaml文件

mkdir -p /data/k8s-yaml/coredns && cd /data/k8s-yaml/coredns cat > /data/k8s-yaml/coredns/rbac.yaml << 'eof' apiVersion: v1 kind: ServiceAccount metadata: name: coredns namespace: kube-system labels: kubernetes.io/cluster-service: "true" addonmanager.kubernetes.io/mode: Reconcile --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRole metadata: labels: kubernetes.io/bootstrapping: rbac-defaults addonmanager.kubernetes.io/mode: Reconcile name: system:coredns rules: - apiGroups: - "" resources: - endpoints - services - pods - namespaces verbs: - list - watch --- apiVersion: rbac.authorization.k8s.io/v1 kind: ClusterRoleBinding metadata: annotations: rbac.authorization.kubernetes.io/autoupdate: "true" labels: kubernetes.io/bootstrapping: rbac-defaults addonmanager.kubernetes.io/mode: EnsureExists name: system:coredns roleRef: apiGroup: rbac.authorization.k8s.io kind: ClusterRole name: system:coredns subjects: - kind: ServiceAccount name: coredns namespace: kube-system eof

1.3.2 configmap.yaml 资源配置清单

cat > /data/k8s-yaml/coredns/configmap.yaml << 'eof' apiVersion: v1 kind: ConfigMap metadata: name: coredns namespace: kube-system data: Corefile: | .:53 { errors log health kubernetes cluster.local 192.168.0.0/16 proxy . /etc/resolv.conf cache 30 } eof

1.3.3 deployment.yaml 控制器资源配置清单

cat > /data/k8s-yaml/coredns/deployment.yaml << 'eof' 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 spec: serviceAccountName: coredns containers: - name: coredns image: harbor.od.com/k8s/coredns:v1.3.1 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 imagePullSecrets: - name: harbor volumes: - name: config-volume configMap: name: coredns items: - key: Corefile path: Corefile eof

1.3.4 svc.yaml service资源配置清单

cat > /data/k8s-yaml/coredns/svc.yaml << 'eof' apiVersion: v1 kind: Service metadata: name: coredns namespace: kube-system labels: k8s-app: coredns kubernetes.io/cluster-service: "true" kubernetes.io/name: "CoreDNS" spec: selector: k8s-app: coredns clusterIP: 192.168.0.2 ports: - name: dns port: 53 protocol: UDP - name: dns-tcp port: 53 eof

1.4 下载kube-dns(coredns)到本地仓库

harbor界面创建K8s项目

docker pull coredns/coredns:1.3.1 docker images | grep coredns coredns/coredns 1.3.1 eb516548c180 20 months ago 40.3MB docker tag eb516548c180 harbor.od.com/k8s/coredns:v1.3.1 docker push harbor.od.com/k8s/coredns:v1.3.1

1.5 配置内网DNS解析

在hdss7-11.host.com上操作

cat >> /var/named/od.com.zone <<'eof' k8s-yaml A 10.4.7.200 eof vi /var/named/od.com.zone 2020092703 ; serial # 日期需要加1 systemctl restart named

1.6 测试访问

1.7 部署kube-dns(coredns)

hdss7-21或hdss7-22任意一台节点上操作

kubectl create secret docker-registry harbor --docker-server=harbor.od.com --docker-username=admin --docker-password=Harbor12345 --docker-email=1934844044@qq.com -n kube-system kubectl apply -f http://k8s-yaml.od.com/coredns/rbac.yaml kubectl apply -f http://k8s-yaml.od.com/coredns/configmap.yaml kubectl apply -f http://k8s-yaml.od.com/coredns/deployment.yaml kubectl apply -f 检查

[root@hdss7-21 ~]# kubectl create deployment nginx-dp --=image=harbor.od.com/public/nginx:v1.7.9 -n kube-public --replicas=1 [root@hdss7-21 ~]# kubectl expose deployment nginx-dp --port=80 -n kube-public [root@hdss7-21 ~]# kubectl get svc -n kube-public # 新建容器集群IP为134结尾 NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE nginx-dp ClusterIP 192.168.109.134 80/TCP 58m [root@hdss7-21 ~]# kubectl get pods -n kube-system -o wide # coredns安装放在kube-system内 NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES coredns-57c78bdbcd-lsf5z 1/1 Running 0 172.7.21.3 hdss7-21.host.com [root@hdss7-21 ~]# kubectl get svc -n kube-system # creodns的svc存在kube-system内 NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE coredns ClusterIP 192.168.0.2 53/UDP,53/TCP 4m30s [root@hdss7-21 ~]# dig -t A nginx-dp.kube-public.svc.cluster.local @192.168.0.2 +short 192.168.109.134 # 查看到能够解析IP，但域名只能在集群内部使用，因为集群IP只能在内网使用 [root@hdss7-21 ~]# dig -t A baidu.com @192.168.0.2 +short # 解析百度 a.shifen.com. 14.215.177.38 14.215.177.39 [root@hdss7-21 ~]# kubectl exec -ti nginx-dp-7f74c75ff9-jtzhs -n kube-public -- /bin/bash root@nginx-dp-7f74c75ff9-jtzhs:/# cat /etc/resolv.conf # 进入容器内查看dns配置了search nameserver 192.168.0.2 search kube-public.svc.cluster.local svc.cluster.local cluster.local host.com options ndots:5 root@nginx-dp-7f74c75ff9-jtzhs:/# ping nginx-dp # 容器内部ping PING nginx-dp.kube-public.svc.cluster.local (192.168.109.134): 48 data bytes 56 bytes from 192.168.109.134: icmp_seq=0 ttl=64 time=0.234 ms

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