# Building a Basic DaemonSet LLMS index: [llms.txt](/llms.txt) --- This page demonstrates how to build a basic that runs a Pod on every node in a Kubernetes cluster. It covers a simple use case of mounting a file from the host, logging its contents using an [init container](/docs/concepts/workloads/pods/init-containers/), and utilizing a pause container. ## Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

A Kubernetes cluster with at least two nodes (one control plane node and one worker node) to demonstrate the behavior of DaemonSets. ## Define the DaemonSet In this task, a basic DaemonSet is created which ensures that the copy of a Pod is scheduled on every node. The Pod will use an init container to read and log the contents of `/etc/machine-id` from the host, while the main container will be a `pause` container, which keeps the Pod running.

    application/basic-daemonset.yaml
    
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: example-daemonset
spec:
  selector:
    matchLabels:
      app.kubernetes.io/name: example
  template:
    metadata:
      labels:
        app.kubernetes.io/name: example
    spec:
      containers:
      - name: pause
        image: registry.k8s.io/pause
      initContainers:
      - name: log-machine-id
        image: busybox:1.37
        command: ['sh', '-c', 'cat /etc/machine-id > /var/log/machine-id.log']
        volumeMounts:
        - name: machine-id
          mountPath: /etc/machine-id
          readOnly: true
        - name: log-dir
          mountPath: /var/log
      volumes:
      - name: machine-id
        hostPath:
          path: /etc/machine-id
          type: File
      - name: log-dir
        hostPath:
          path: /var/log

1. Create a DaemonSet based on the (YAML) manifest: ```shell kubectl apply -f https://k8s.io/examples/application/basic-daemonset.yaml ``` 1. Once applied, you can verify that the DaemonSet is running a Pod on every node in the cluster: ```shell kubectl get pods -o wide ``` The output will list one Pod per node, similar to: ``` NAME READY STATUS RESTARTS AGE IP NODE example-daemonset-xxxxx 1/1 Running 0 5m x.x.x.x node-1 example-daemonset-yyyyy 1/1 Running 0 5m x.x.x.x node-2 ``` 1. You can inspect the contents of the logged `/etc/machine-id` file by checking the log directory mounted from the host: ```shell kubectl exec -- cat /var/log/machine-id.log ``` Where `` is the name of one of your Pods. ## Cleaning up To delete the DaemonSet, run this command: ```shell kubectl delete --cascade=foreground --ignore-not-found --now daemonsets/example-daemonset ``` This simple DaemonSet example introduces key components like init containers and host path volumes, which can be expanded upon for more advanced use cases. For more details refer to [DaemonSet](/docs/concepts/workloads/controllers/daemonset/). ## What's next * See [Performing a rolling update on a DaemonSet](/docs/tasks/manage-daemon/update-daemon-set/) * See [Creating a DaemonSet to adopt existing DaemonSet pods](/docs/concepts/workloads/controllers/daemonset/)