14-DaemonSets

DaemonSets

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In this section, we will take a look at DaemonSets.

DaemonSets are like replicasets, as it helps in to deploy multiple instances of pod. But it runs one copy of your pod on each node in your cluster.

DaemonSets - UseCases

DaemonSets - Definition

• Creating a DaemonSet is similar to the ReplicaSet creation process.

• For DaemonSets, we start with apiVersion, kind as DaemonSets instead of ReplicaSet, metadata and spec.

  apiVersion: apps/v1
  kind: Replicaset
  metadata:
    name: monitoring-daemon
    labels:
      app: nginx
  spec:
    selector:
      matchLabels:
        app: monitoring-agent
    template:
      metadata:
       labels:
         app: monitoring-agent
      spec:
        containers:
        - name: monitoring-agent
          image: monitoring-agent
  

  apiVersion: apps/v1
  kind: DaemonSet
  metadata:
    name: monitoring-daemon
    labels:
      app: nginx
  spec:
    selector:
      matchLabels:
        app: monitoring-agent
    template:
      metadata:
       labels:
         app: monitoring-agent
      spec:
        containers:
        - name: monitoring-agent
          image: monitoring-agent
  

  

• To create a daemonset from a definition file

  $ kubectl create -f daemon-set-definition.yaml
  

View DaemonSets

• To list daemonsets

  $ kubectl get daemonsets
  

• For more details of the daemonsets

  $ kubectl describe daemonsets monitoring-daemon
  

  

How DaemonSets Works

K8s Reference Docs

• https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/#writing-a-daemonset-spec