4.kubernetes的服务发现插件-CoreDNS

1.1.部署K8S内网资源清单http服务

1.2.部署coredns

部署K8S内网资源清单http服务

在运维主机HDSS7-200.host.com上,配置一个nginx虚拟主机,用以提高k8s统一的资源配置清单访问入口

• 配置nginx

[root@hdss7-200 ~]# vi /etc/nginx/conf.d/k8s-yaml.fx.com.conf
server {
    listen       80;
    server_name  k8s-yaml.fx.com;

    location / {
        autoindex on;
        default_type text/plain;
        root /data/k8s-yaml;
    }
}
[root@hdss7-200 ~]# nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
[root@hdss7-200 ~]# nginx -s reload
[root@hdss7-200 ~]# cd /data
[root@hdss7-200 data]# mkdir k8s-yaml
[root@hdss7-200 data]# cd k8s-yaml/
[root@hdss7-200 k8s-yaml]# mkdir coredns
[root@hdss7-200 k8s-yaml]# 

• 配置dns解析

[root@hdss7-11 ~]# vi /var/named/fx.com.zone 
$ORIGIN fx.com.
$TTL 600        ; 10 minutes
@               IN SOA  dns.fx.com. dnsadmin.fx.com. (
                        2020060903  ; serial
                         10800      ; refresh (3 hours)
                         900        ; retry (15 minutes)
                         604800     ; expire (1 week)
                         86400      ; minimum (1 day)
                         )
                        NS      dns.fx.com.
$TTL 60 ; 1 minute
dns             A       10.4.7.11
harbor          A       10.4.7.200
k8s-yaml        A       10.4.7.200
[root@hdss7-11 ~]# systemctl restart named
[root@hdss7-11 ~]# dig -t A k8s-yaml.fx.com @10.4.7.11 +short
10.4.7.200

下载coredns(docker)镜像并打包上传到harbor仓库

[root@hdss7-200 k8s-yaml]# docker pull coredns/coredns:1.6.1
[root@hdss7-200 k8s-yaml]# docker tag c0f6e815079e harbor.fx.com/public/coredns:v1.6.1
[root@hdss7-200 k8s-yaml]# docker push harbor.fx.com/public/coredns:v1.6.1

准备资源配置清单

[root@hdss7-200 ~]#  mkdir -p /data/k8s-yaml/coredns && cd /data/k8s-yaml/coredns/

• rbac.yaml

[root@hdss7-200 coredns]# vi rbac.yaml
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

• configmap.yaml

[root@hdss7-200 coredns]# vi cm.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: coredns
  namespace: kube-system
data:
  Corefile: |
    .:53 {
        errors
        log
        health
        ready
        kubernetes cluster.local 192.168.0.0/16
        forward . 10.4.7.11
        cache 30
        loop
        reload
        loadbalance
       }

• dp.yaml

[root@hdss7-200 coredns]# vi dp.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: coredns
  namespace: kube-system
  labels:
    k8s-app: coredns
    kubernetes.io/name: "CoreDNS"
spec:
  replicas: 1
  selector:
    matchLabels:
      k8s-app: coredns
  template:
    metadata:
      labels:
        k8s-app: coredns
    spec:
      priorityClassName: system-cluster-critical
      serviceAccountName: coredns
      containers:
      - name: coredns
        image: harbor.fx.com/public/coredns:v1.6.1
        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
        - containerPort: 9153
          name: metrics
          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

• svc.yaml

[root@hdss7-200 coredns]# vi svc.yaml
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
  - name: metrics
    port: 9153
    protocol: TCP

 应用资源配置清单

[root@hdss7-21 ~]# kubectl apply -f http://k8s-yaml.fx.com/coredns/rbac.yaml
serviceaccount/coredns created
clusterrole.rbac.authorization.k8s.io/system:coredns created
clusterrolebinding.rbac.authorization.k8s.io/system:coredns created
[root@hdss7-21 ~]# kubectl apply -f http://k8s-yaml.fx.com/coredns/cm.yaml
configmap/coredns created
[root@hdss7-21 ~]# kubectl apply -f http://k8s-yaml.fx.com/coredns/dp.yaml
deployment.apps/coredns created
[root@hdss7-21 ~]# kubectl apply -f http://k8s-yaml.fx.com/coredns/svc.yaml
service/coredns created
[root@hdss7-21 ~]# kubectl get all -n kube-system
NAME                           READY   STATUS    RESTARTS   AGE
pod/coredns-65cb567d6f-4x5tn   1/1     Running   0          32s


NAME              TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)                  AGE
service/coredns   ClusterIP   192.168.0.2   <none>        53/UDP,53/TCP,9153/TCP   26s


NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/coredns   1/1     1            1           32s

NAME                                 DESIRED   CURRENT   READY   AGE
replicaset.apps/coredns-65cb567d6f   1         1         1       32s

验证coredns

[root@hdss7-21 ~]# dig -t A www.baidu.com @192.168.0.2 +short
www.a.shifen.com.
220.181.38.150
220.181.38.149
[root@hdss7-21 ~]# kubectl get svc -n kube-public
NAME       TYPE        CLUSTER-IP        EXTERNAL-IP   PORT(S)   AGE
nginx-dp   ClusterIP   192.168.164.107   <none>        80/TCP    28h
[root@hdss7-21 ~]# dig -t A nginx-dp.kube-public.svc.cluster.local. @192.168.0.2 +short
192.168.164.107
[root@hdss7-21 ~]# kubectl get pods -o wide
NAME             READY   STATUS    RESTARTS   AGE     IP           NODE                NOMINATED NODE   READINESS GATES
nginx-ds-ffw5x   1/1     Running   0          3h48m   172.7.22.2   hdss7-22.host.com   <none>           <none>
nginx-ds-t2scb   1/1     Running   0          3h47m   172.7.21.2   hdss7-21.host.com   <none>           <none>
[root@hdss7-21 ~]# kubectl exec -it nginx-ds-ffw5x /bin/bash
root@nginx-ds-ffw5x:/# curl nginx-dp.kube-public
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
         35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>