DaemonSet

1.概念阐述

DaemonSet：守护进程集，缩写为ds，在所有节点或者是匹配的节点上都部署一个Pod。
DaemonSet确保全部（或者某些）节点上运行一个Pod副本。当有新节点加入集群时，也会为它们新增一个Pod。当节点从集群中移除时，这些Pod也会被回收，删除DaemonSet将会删除它创建的所有Pod
  使用DaemonSet的一些典型用法：
	 运行集群存储daemon（守护进程），例如在每个节点上运行Glusterd、Ceph等
	 在每个节点运行日志收集daemon，例如Fluentd、Logstash
	 在每个节点运行监控daemon，比如Prometheus Node Exporter、Collectd、Datadog代理、New Relic代理或 Ganglia gmond

2.创建一个DaemonSet

[root@k8s-master01 ~]# cat > nginx-ds.yaml  << EFO
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:
      - image: nginx:1.15.2
        imagePullPolicy: IfNotPresent
        name: nginx
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Alwaysyaml
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
EFO

3.创建一个ds

# 创建一个ds
[root@k8s-master01 ~]# kubectl create -f nginx-ds.yaml 
daemonset.apps/nginx created

# 查看ds信息，个个节点都有一个
[root@k8s-master01 ~]# kubectl get node -owide
NAME           STATUS   ROLES    AGE   VERSION   INTERNAL-IP     EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION                CONTAINER-RUNTIME
k8s-master01   Ready    matser   43h   v1.20.0   192.168.1.100   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.14
k8s-master02   Ready    <none>   43h   v1.20.0   192.168.1.101   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.14
k8s-master03   Ready    <none>   43h   v1.20.0   192.168.1.102   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.14
k8s-node01     Ready    <none>   43h   v1.20.0   192.168.1.103   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.14
k8s-node2      Ready    <none>   43h   v1.20.0   192.168.1.104   <none>        CentOS Linux 7 (Core)   4.19.12-1.el7.elrepo.x86_64   docker://19.3.14

4.给node节点打lable

[root@k8s-master01 ~]# kubectl label node k8s-node01 k8s-node02 ds=true
[root@k8s-master01 ~]# kubectl get node --show-labels  ### 查看标签

5.更新

[root@k8s-master01 ~]# cat -n nginx-ds.yaml 
     1	apiVersion: apps/v1
     2	kind: DaemonSet
     3	metadata:
     4	  labels:
     5	    app: nginx
     6	  name: nginx
     7	spec:
     8	  revisionHistoryLimit: 10
     9	  selector:
    10	    matchLabels:
    11	      app: nginx
    12	  template:
    13	    metadata:
    14	      creationTimestamp: null
    15	      labels:
    16	        app: nginx
    17	    spec:
    18	      nodeSelector: # 新增
    19	        ds: "ture"  # 定义我们打label的节点上起DS pod
    20	      containers:
    21	      - image: nginx:1.15.2
    22	        imagePullPolicy: IfNotPresent
    23	        name: nginx
    24	        resources: {}
    25	        terminationMessagePath: /dev/termination-log
    26	        terminationMessagePolicy: File
    27	      dnsPolicy: ClusterFirst
    28	      restartPolicy: Always
    29	      schedulerName: default-scheduler
    30	      securityContext: {}
    31	      terminationGracePeriodSeconds: 30
[root@k8s-master01 ~]# kubectl replace -f nginx-ds.yaml 

6.验证查看

[root@k8s-master01 ~]# kubectl get pod -owide
NAME                     READY   STATUS    RESTARTS   AGE     IP               NODE         NOMINATED NODE   READINESS GATES
nginx-cpbpb              1/1     Running   0          7m51s   172.16.85.242    k8s-node01   <none>           <none>
nginx-hmwxf              1/1     Running   0          7m37s   172.16.169.137   k8s-node2    <none>           <none>