Kubernetes1.15 部署 coredns

coredns.yaml文件如下所示

# __MACHINE_GENERATED_WARNING__

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
- apiGroups:
  - ""
  resources:
  - nodes
  verbs:
  - get
---
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
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: coredns
  namespace: kube-system
  labels:
      addonmanager.kubernetes.io/mode: EnsureExists
data:
  Corefile: |
    .: {
        errors
        health
        kubernetes cluster.local in-addr.arpa ip6.arpa {
            pods insecure
            upstream
            fallthrough in-addr.arpa ip6.arpa
            ttl
        }
        prometheus :
        forward . /etc/resolv.conf
        cache
        loop
        reload
        loadbalance
    }
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: coredns
  namespace: kube-system
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
    kubernetes.io/name: "CoreDNS"
spec:
  # replicas: not specified here:
  # . In order to make Addon Manager do not reconcile this replicas parameter.
  # . Default is .
  # . Will be tuned in real time if DNS horizontal auto-scaling is turned on.
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable:
  selector:
    matchLabels:
      k8s-app: kube-dns
  template:
    metadata:
      labels:
        k8s-app: kube-dns
      annotations:
        seccomp.security.alpha.kubernetes.io/pod: 'docker/default'
    spec:
      priorityClassName: system-cluster-critical
      serviceAccountName: coredns
      tolerations:
        - key: "CriticalAddonsOnly"
          operator: "Exists"
      nodeSelector:
        beta.kubernetes.io/os: linux
      containers:
      - name: coredns
        image: k8s.gcr.io/coredns:
        imagePullPolicy: IfNotPresent
        resources:
          limits:
            memory: 70Mi
          requests:
            cpu: 100m
            memory: 70Mi
        args: [ "-conf", "/etc/coredns/Corefile" ]
        volumeMounts:
        - name: config-volume
          mountPath: /etc/coredns
          readOnly: true
        ports:
        - containerPort:
          name: dns
          protocol: UDP
        - containerPort:
          name: dns-tcp
          protocol: TCP
        - containerPort:
          name: metrics
          protocol: TCP
        livenessProbe:
          httpGet:
            path: /health
            port:
            scheme: HTTP
          initialDelaySeconds:
          timeoutSeconds:
          successThreshold:
          failureThreshold:
        readinessProbe:
          httpGet:
            path: /health
            port:
            scheme: HTTP
        securityContext:
          allowPrivilegeEscalation: false
          capabilities:
            add:
            - NET_BIND_SERVICE
            drop:
            - all
          readOnlyRootFilesystem: true
      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
  annotations:
    prometheus.io/port: "
    prometheus.io/scrape: "true"
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
    addonmanager.kubernetes.io/mode: Reconcile
    kubernetes.io/name: "CoreDNS"
spec:
  selector:
    k8s-app: kube-dns
  clusterIP: 10.0.0.2
  ports:
  - name: dns
    port:
    protocol: UDP
  - name: dns-tcp
    port:
    protocol: TCP
  - name: metrics
    port:
    protocol: TCP

修改以上yaml文件中红色部分修改成自己对于的信息

kubectl apply -f coredns.yaml

执行apply  生成pod（需要替换镜像，不然会拉取失败）

[root@k8s-master yaml]# kubectl get all -n kube-system | grep coredns
pod/coredns-867ccfd476-9ghff              /     Running            42h
pod/coredns-867ccfd476-p5md4              /     Running            42h
deployment.apps/coredns                /                            44h
replicaset.apps/coredns-867ccfd476                                       44h
[root@k8s-master yaml]# 

创建测试的pod

[root@k8s-master test]# cat my-apache.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: my-apache
spec:
  replicas:
  template:
    metadata:
      labels:
        run: my-apache
    spec:
      containers:
      - name: my-apache
        image: httpd:2.4
        ports:
        - containerPort: 

---
apiVersion: v1
kind: Service
metadata:
  name: my-apache
  labels:
    run: my-apache
spec:
  type: NodePort
  ports:
  - port:
    targetPort:
    nodePort:
  selector:
    run: my-apache

生成pod

[root@k8s-master test]# kubectl apply -f my-apache.yaml

查看pod运行状态

[root@k8s-master test]# kubectl get pod
NAME                         READY   STATUS    RESTARTS   AGE
my-apache-75f574f468-8psfw   /     Running             24h
my-apache-75f574f468-msrrn   /     Running             24h
[root@k8s-master test]# 

已经全部运行

[root@k8s-master test]# kubectl get svc
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   /TCP        2d
my-apache    NodePort    :/TCP   24h
[root@k8s-master test]# curl 10.0.0.71
<html><body><h1>It works!</h1></body></html>
[root@k8s-master test]# 

由此可见dns服务是可用的