[root@k8s-master01 ~]# kubectl get nodes
NAME           STATUS   ROLES    AGE   VERSION
k8s-master01   Ready    <none>   8d    v1.23.3
k8s-master02   Ready    <none>   8d    v1.23.3
k8s-master03   Ready    <none>   8d    v1.23.3
k8s-node01     Ready    <none>   8d    v1.23.3
k8s-node02     Ready    <none>   8d    v1.23.3

比如從上段代碼中可以看到我們集群有五個(gè)節(jié)點(diǎn)，Daemon會(huì)在這五個(gè)節(jié)點(diǎn)都部署一個(gè)Pod；又或者我們只需要在node節(jié)點(diǎn)部署，那么可以利用標(biāo)簽的方式只在node節(jié)點(diǎn)上部署Pod。比如我們的calico網(wǎng)絡(luò)插件就是用DaemonSet部署的。

DaemonSet 的使用場(chǎng)景：

監(jiān)控?cái)?shù)據(jù)收集：需要每個(gè)節(jié)點(diǎn)上收集數(shù)據(jù)
監(jiān)控節(jié)點(diǎn)狀態(tài)
負(fù)責(zé)每個(gè)節(jié)點(diǎn)的網(wǎng)絡(luò)、存儲(chǔ)等組件，如calico、ceph等

DaemonSet的使用：

apiVersion: apps/v1
kind: DaemonSet
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.18.0
        imagePullPolicy: Always
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30

注意：沒有副本數(shù)的參數(shù)

創(chuàng)建一個(gè)ds；然后查看可以看到每個(gè)節(jié)點(diǎn)上都生成了一個(gè)nginx副本。

[root@k8s-master01 ~]# kubectl create -f nginx-ds.yaml 
daemonset.apps/nginx created
[root@k8s-master01 ~]# kubectl get pod -o wide 
NAME          READY   STATUS    RESTARTS         AGE    IP               NODE           NOMINATED NODE   READINESS GATES
busybox       1/1     Running   21 (2m45s ago)   8d     172.27.14.193    k8s-node02     <none>           <none>
nginx-2c7xf   1/1     Running   0                2m2s   172.25.92.79     k8s-master02   <none>           <none>
nginx-kjdx8   1/1     Running   0                2m2s   172.25.244.200   k8s-master01   <none>           <none>
nginx-wwltz   1/1     Running   0                2m2s   172.27.14.199    k8s-node02     <none>           <none>
nginx-zl2lr   1/1     Running   0                2m2s   172.18.195.19    k8s-master03   <none>           <none>
nginx-znprg   1/1     Running   0                2m2s   172.17.125.7     k8s-node01     <none>           <none>

需要注意的地方：