本頁面由 Cloud Translation API 翻譯而成。

設定自訂 kube-dns 部署作業

標準

本頁說明如何為 Google Kubernetes Engine (GKE) 標準模式叢集執行 kube-dns 的自訂 Deployment。本頁面不適用於 GKE Autopilot，因為 Google 會管理 kube-dns。

總覽

如要設定 kube-dns CPU、記憶體和其他參數，您必須執行自訂 Deployment，並停用 GKE 提供的 Deployment。您也可以按照本頁的操作說明，執行 Core DNS 或任何其他 DNS 供應商的自訂部署作業，這些供應商都遵循 Kubernetes DNS 規格。

如要進一步瞭解 GKE 如何實作服務探索，請參閱「服務探索和 DNS」。

建立自訂部署作業

為 kube-dns、Core DNS 或其他 DNS 供應商建立 Deployment 資訊清單。

下列 kube-dns 資訊清單範例包含 -q 標記，可記錄查詢結果。將資訊清單儲存為 custom-kube-dns.yaml。

apiVersion: apps/v1
kind: Deployment
metadata:
  name: DNS_DEPLOYMENT_NAME
  namespace: kube-system
  annotations:
    deployment.kubernetes.io/revision: "1"
    k8s-app: kube-dns
spec:
  selector:
    matchLabels:
      k8s-app: kube-dns
  strategy:
    rollingUpdate:
      maxSurge: 10%
      maxUnavailable: 0
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        k8s-app: kube-dns
    spec:
      containers:
      - name: kubedns
        image: registry.k8s.io/dns/k8s-dns-kube-dns:1.17.3
        resources:
          limits:
            memory: '170Mi'
          requests:
            cpu: 100m
            memory: '70Mi'
        livenessProbe:
          httpGet:
            path: /healthcheck/kubedns
            port: 10054
            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
        - --config-dir=/kube-dns-config
        - --v=2
        env:
        - name: PROMETHEUS_PORT
          value: "10055"
        ports:
        - containerPort: 10053
          name: dns-local
          protocol: UDP
        - containerPort: 10053
          name: dns-tcp-local
          protocol: TCP
        - containerPort: 10055
          name: metrics
          protocol: TCP
        volumeMounts:
        - name: kube-dns-config
          mountPath: /kube-dns-config
        securityContext:
          allowPrivilegeEscalation: false
          readOnlyRootFilesystem: true
          runAsUser: 1001
          runAsGroup: 1001
      - name: dnsmasq
        image: registry.k8s.io/dns/k8s-dns-dnsmasq-nanny:1.17.3
        livenessProbe:
          httpGet:
            path: /healthcheck/dnsmasq
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - -v=2
        - -logtostderr
        - -configDir=/etc/k8s/dns/dnsmasq-nanny
        - -restartDnsmasq=true
        - --
        - -k
        - --cache-size=1000
        - --no-negcache
        - --dns-forward-max=1500
        - --log-facility=-
        - --server=/cluster.local/127.0.0.1#10053
        - --server=/in-addr.arpa/127.0.0.1#10053
        - --server=/ip6.arpa/127.0.0.1#10053
        ports:
        - containerPort: 53
          name: dns
          protocol: UDP
        - containerPort: 53
          name: dns-tcp
          protocol: TCP
        resources:
          requests:
            cpu: 150m
            memory: 20Mi
        volumeMounts:
        - name: kube-dns-config
          mountPath: /etc/k8s/dns/dnsmasq-nanny
        securityContext:
          capabilities:
            drop:
            - all
            add:
            - NET_BIND_SERVICE
            - SETGID
      - name: sidecar
        image: registry.k8s.io/dns/k8s-dns-sidecar:1.17.3
        livenessProbe:
          httpGet:
            path: /metrics
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - --v=2
        - --logtostderr
        - --probe=kubedns,127.0.0.1:10053,kubernetes.default.svc.cluster.local,5,SRV
        - --probe=dnsmasq,127.0.0.1:53,kubernetes.default.svc.cluster.local,5,SRV
        ports:
        - containerPort: 10054
          name: metrics
          protocol: TCP
        resources:
          requests:
            memory: 20Mi
            cpu: 10m
        securityContext:
          allowPrivilegeEscalation: false
          readOnlyRootFilesystem: true
          runAsUser: 1001
          runAsGroup: 1001
      dnsPolicy: Default
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      serviceAccount: kube-dns
      serviceAccountName: kube-dns
      terminationGracePeriodSeconds: 30
      tolerations:
      - key: CriticalAddonsOnly
        operator: Exists
      volumes:
      - configMap:
          defaultMode: 420
          name: kube-dns
          optional: true
        name: kube-dns-config

將 DNS_DEPLOYMENT_NAME 替換為自訂 kube-dns Deployment 的名稱。

將資訊清單套用至叢集：
```
kubectl create -f custom-kube-dns.yaml
```
確認 Pod 正在執行：
```
kubectl get pods -n kube-system -l=k8s-app=kube-dns
```
輸出內容會與下列內容類似，顯示自訂 kube-dns Pod：
```
NAME                               READY   STATUS    RESTARTS   AGE
custom-kube-dns-5685645b44-kzs8w   3/3     Running   0          22h
```
新的 Deployment 與 kube-dns 具有相同的選取器，這表示 Pod 會使用相同的 kube-dns 服務 IP 位址，與執行自訂 kube-dns Deployment 的 Pod 通訊。

完成這個步驟後，請按照下一節的步驟縮減 kube-dns。

縮減 kube-dns

使用下列指令將 kube-dns Deployment 和自動調度器縮放為零，即可停用 GKE 管理的 kube-dns：

kubectl scale deployment --replicas=0 kube-dns-autoscaler --namespace=kube-system
kubectl scale deployment --replicas=0 kube-dns --namespace=kube-system

建立自訂自動調度器

如果自訂 DNS 需要自動調度資源，您必須設定及部署個別的自動調度器。kube-dns-autoscaler 只會調度叢集上的預設 kube-dns Deployment。您也需要為自動配置器設定自訂 ClusterRole，並新增修改自訂 kube-dns 部署作業的權限。

為自動配置器建立 ClusterRole 和 Deployment 資訊清單，並將資訊清單儲存為 custom-dns-autoscaler.yaml：

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: system:custom-dns-autoscaler
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: system:custom-dns-autoscaler
subjects:
- kind: ServiceAccount
  name: kube-dns-autoscaler
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: system:custom-dns-autoscaler
rules:
- apiGroups:
  - ""
  resources:
  - nodes
  verbs:
  - list
  - watch
- apiGroups:
  - apps
  resourceNames:
  - DNS_DEPLOYMENT_NAME
  resources:
  - deployments/scale
  verbs:
  - get
  - update
- apiGroups:
  - ""
  resources:
  - configmaps
  verbs:
  - get
  - create
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: custom-dns-autoscaler
  namespace: kube-system
  labels:
    k8s-app: custom-dns-autoscaler
spec:
  selector:
    matchLabels:
      k8s-app: custom-dns-autoscaler
  template:
    metadata:
      labels:
        k8s-app: custom-dns-autoscaler
      annotations:
        seccomp.security.alpha.kubernetes.io/pod: 'docker/default'
    spec:
      priorityClassName: system-cluster-critical
      securityContext:
        supplementalGroups: [ 65534 ]
        fsGroup: 65534
      nodeSelector:
        kubernetes.io/os: linux
      containers:
      - name: autoscaler
        image: registry.k8s.io/cluster-proportional-autoscaler-amd64:1.7.1
        resources:
            requests:
                cpu: "20m"
                memory: "10Mi"
        command:
          - /cluster-proportional-autoscaler
          - --namespace=kube-system
          - --configmap=custom-dns-autoscaler
          - --target=Deployment/DNS_DEPLOYMENT_NAME
          - --default-params={"linear":{"coresPerReplica":256,"nodesPerReplica":16,"preventSinglePointFailure":true}}
          - --logtostderr=true
          - --v=2
      tolerations:
      - key: "CriticalAddonsOnly"
        operator: "Exists"
      serviceAccountName: kube-dns-autoscaler

將資訊清單套用至叢集：

kubectl create -f custom-dns-autoscaler.yaml

後續步驟

閱讀總覽，瞭解 GKE 如何提供受管理 DNS。
如要瞭解 Kubernetes 叢集如何使用 DNS，請參閱「服務和 Pod 的 DNS」。