DaemonSet确保在所有（或部分）Node节点上运行Pod的副本。随着新的Node被添加到群集中的同时，会将Pod添加到新Node中。随着节点从群集中删除，垃圾收集器也将会删除这些Pod。DaemonSet的一些典型场景和用法：

    • 集群存储：在每个Node节点上，运行集群存储守护程序，例如glusterd，ceph。
    • 日志收集：在每个Node节点上，运行日志收集守护程序，例如fluentd或logstash。
    • 节点监控：在每个Node节点上，运行节点监控守护程序，例如Prometheus Node Exporter,collectd，Dynatrace OneAgent，Datadog agent，New Relic agent，Ganglia gmond或者Instana agent
    1. apiVersion: apps/v1
    2. kind: DaemonSet
    3. metadata:
    4.   name: fluentd-elasticsearch
    5.   namespace: kube-system
    6.   labels:
    7.     k8s-app: fluentd-logging
    8. spec:
    9.   selector:
    10.     matchLabels:
    11.       name: fluentd-elasticsearch
    12.   template:
    13.     metadata:
    14.       labels:
    15.         name: fluentd-elasticsearch
    16.     spec:
    17.       tolerations:
    18.       - key: node-role.kubernetes.io/master
    19.         effect: NoSchedule
    20.       containers:
    21.       - name: fluentd-elasticsearch
    22.         image: k8s.gcr.io/fluentd-elasticsearch:1.20
    23.         resources:
    24.           limits:
    25.             memory: 200Mi
    26.           requests:
    27.             cpu: 100m
    28.             memory: 200Mi
    29.         volumeMounts:
    30.         - name: varlog
    31.           mountPath: /var/log
    32.         - name: varlibdockercontainers
    33.           mountPath: /var/lib/docker/containers
    34.           readOnly: true
    35.       terminationGracePeriodSeconds: 30
    36.       volumes:
    37.       - name: varlog
    38.         hostPath:
    39.           path: /var/log
    40.       - name: varlibdockercontainers
    41.         hostPath:
    42.           path: /var/lib/docker/containers