Kubernetes 之 DaemonSet 基本原理

DaemonSet 定義

DaemonSet 確保全部（或者某些）節點上運行一個 Pod 的副本。 當有節點加入集群時， 也會為他們新增一個 Pod 。 當有節點從集群移除時，這些 Pod 也會被回收。刪除 DaemonSet 將會刪除它創建的所有 Pod。它最經常被使用在收集集群日志的用途上。

DaemonSet 使用

apiVersion: apps/v1
kind: DaemonSet
metadata:name: fluentd-elasticsearchnamespace: kube-systemlabels:k8s-app: fluentd-logging
spec:selector:matchLabels:name: fluentd-elasticsearchtemplate:metadata:labels:name: fluentd-elasticsearchspec:tolerations:# 這些容忍度設置是為了讓該守護進程集在控制平面節點上運行# 如果你不希望自己的控制平面節點運行 Pod，可以刪除它們- key: node-role.kubernetes.io/control-planeoperator: Existseffect: NoSchedule- key: node-role.kubernetes.io/masteroperator: Existseffect: NoSchedulecontainers:- name: fluentd-elasticsearchimage: quay.io/fluentd_elasticsearch/fluentd:v2.5.2resources:limits:memory: 200Mirequests:cpu: 100mmemory: 200MivolumeMounts:- name: varlogmountPath: /var/log# 可能需要設置較高的優先級類以確保 DaemonSet Pod 可以搶占正在運行的 Pod# priorityClassName: importantterminationGracePeriodSeconds: 30volumes:- name: varloghostPath:path: /var/log

root@k8s-master1:~# kubectl get ds -n kube-system
NAME                    DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR            AGE
fluentd-elasticsearch   3         3         3       3            3           <none>                   112s
kube-proxy              3         3         3       3            3           kubernetes.io/os=linux   18droot@k8s-master1:~# kubectl get pods -n kube-system -owide -l name=fluentd-elasticsearch
NAME                          READY   STATUS    RESTARTS   AGE    IP               NODE          NOMINATED NODE   READINESS GATES
fluentd-elasticsearch-6fmkb   1/1     Running   0          3m8s   10.244.194.122   k8s-worker1   <none>           <none>
fluentd-elasticsearch-pd4ps   1/1     Running   0          3m8s   10.244.159.156   k8s-master1   <none>           <none>
fluentd-elasticsearch-tkkvq   1/1     Running   0          3m8s   10.244.126.2     k8s-worker2   <none>           <none>