Kubernetes-DaemonSet

2023-10-18

字数统计: 1.1k字 | 阅读时长≈ 6分

DaemonSet 是什么

DaemonSet: 守护进程集，缩写为 ds，在所有节点或者是匹配的节点上部署一个 Pod。

使用 DaemonSet 的场景：

运行集群存储的 daemon：比如 ceph，glusterd
节点的 CNI 网络插件：Calico
节点日志的收集，fluentd 或者 filebeat
节点的监控：node exporter
服务暴露：部署一个 ingress nginx

每个节点创建一个 DaemonSet

创建一个 DaemonSet 示例 nginx-ds.yaml 文件，如下

apiVersion: apps/v1
kind: DaemonSet
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.15.2
        imagePullPolicy: IfNotPresent
      restartPolicy: Always
      terminationGracePeriodSeconds: 30

创建一个 ds

1 2	# kubectl create -f nginx-ds.yaml daemonset.apps/nginx created

查看节点信息以及 ds 生成的 Pod 信息

# kubectl get nodes -owide
NAME            STATUS   ROLES    AGE   VERSION   INTERNAL-IP      EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION                CONTAINER-RUNTIME
k8s-master-01   Ready    master   57d   v1.19.7   192.168.200.18   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.15
k8s-master-02   Ready    master   57d   v1.19.7   192.168.200.19   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.15
k8s-master-03   Ready    master   57d   v1.19.7   192.168.200.20   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.15
k8s-node-01     Ready    node     57d   v1.19.7   192.168.200.21   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.15
k8s-node-02     Ready    node     57d   v1.19.7   192.168.200.22   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.15

# kubectl get pod -owide
NAME          READY   STATUS    RESTARTS   AGE   IP               NODE            NOMINATED NODE   READINESS GATES
nginx-7vhgv   1/1     Running   0          66s   172.19.98.152    k8s-node-02     <none>           <none>
nginx-949mg   1/1     Running   0          66s   172.30.107.90    k8s-master-01   <none>           <none>
nginx-jz5pl   1/1     Running   0          66s   172.21.176.218   k8s-master-02   <none>           <none>
nginx-lzpwj   1/1     Running   0          66s   172.20.183.153   k8s-master-03   <none>           <none>
nginx-pvg2p   1/1     Running   0          66s   172.31.44.33     k8s-node-01     <none>           <none>

按照标签选择器部署 DS

给所有的 node 节点添加一个 ds=true 的标签

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# kubectl label node k8s-node-01 k8s-node-02 ds=true
node/k8s-node-01 labeled
node/k8s-node-02 labeled

查看节点信息

# kubectl get nodes --show-labels 
NAME            STATUS   ROLES    AGE   VERSION   LABELS
k8s-master-01   Ready    master   57d   v1.19.7   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master-01,kubernetes.io/os=linux,node-role.kubernetes.io/master=,node.kubernetes.io/node=
k8s-master-02   Ready    master   57d   v1.19.7   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master-02,kubernetes.io/os=linux,node-role.kubernetes.io/master=,node.kubernetes.io/node=
k8s-master-03   Ready    master   57d   v1.19.7   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master-03,kubernetes.io/os=linux,node-role.kubernetes.io/master=,node.kubernetes.io/node=
k8s-node-01     Ready    node     57d   v1.19.7   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,ds=true,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node-01,kubernetes.io/os=linux,node-role.kubernetes.io/node=,node.kubernetes.io/node=
k8s-node-02     Ready    node     57d   v1.19.7   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,ds=true,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node-02,kubernetes.io/os=linux,node-role.kubernetes.io/node=,node.kubernetes.io/node=

修改 nginx-ds.yaml 文件在文件最下面添加 nodeSelector 属性，如下。

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:1.15.2
        imagePullPolicy: IfNotPresent
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
    dnsPolicy: ClusterFirst
    restartPolicy: Always
    schedulerName: default-scheduler
    securityContext: {}
    terminationGracePeriodSeconds: 30
    nodeSelector:
        ds: "true"

使用 replace 命令更新 ds

1 2	# kubectl replace -f nginx-ds.yaml daemonset.apps/nginx replaced

再次查看运行的 Pod

# kubectl get pod
NAME          READY   STATUS    RESTARTS   AGE
nginx-5kgxb   1/1     Running   0          65s
nginx-6522j   1/1     Running   0          58s

# kubectl get pod -o wide
NAME          READY   STATUS    RESTARTS   AGE     IP              NODE          NOMINATED NODE   READINESS GATES
nginx-5kgxb   1/1     Running   0          2m18s   172.31.44.34    k8s-node-01   <none>           <none>
nginx-6522j   1/1     Running   0          2m11s   172.19.98.153   k8s-node-02   <none>           <none>

DaemonSet 扩容

新节点运行 ds，比如需要在 k8s-master-01 节点上部署 ds，只需要给 k8s-master-01 节点添加一个 ds=true 的标签即可
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# kubectl label nodes k8s-master-01 ds=true
node/k8s-master-01 labeled

查看最新的 Pod 部署状态

# kubectl get pods -owide
NAME          READY   STATUS    RESTARTS   AGE     IP              NODE            NOMINATED NODE   READINESS GATES
nginx-5kgxb   1/1     Running   0          6m52s   172.31.44.34    k8s-node-01     <none>           <none>
nginx-6522j   1/1     Running   0          6m45s   172.19.98.153   k8s-node-02     <none>           <none>
nginx-vqdnv   1/1     Running   0          31s     172.30.107.91   k8s-master-01   <none>           <none>

DaemonSet 的更新与回滚

StatefulSet，DaemonSet 的更新和回滚和 Deployment 一致；