Assign Pods to Nodes

This page shows how to assign a Kubernetes Pod to a particular node in a Kubernetes cluster.

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:

To check the version, enter kubectl version.

Add a label to a node

  1. List the nodes in your cluster, along with their labels:

    1. kubectl get nodes --show-labels

    The output is similar to this:

    1. NAME      STATUS    ROLES    AGE     VERSION        LABELS
    2. worker0   Ready     <none>   1d      v1.13.0        ...,kubernetes.io/hostname=worker0
    3. worker1   Ready     <none>   1d      v1.13.0        ...,kubernetes.io/hostname=worker1
    4. worker2   Ready     <none>   1d      v1.13.0        ...,kubernetes.io/hostname=worker2

  2. Chose one of your nodes, and add a label to it:

    1. kubectl label nodes <your-node-name> disktype=ssd

    where <your-node-name> is the name of your chosen node.

  3. Verify that your chosen node has a disktype=ssd label:

    1. kubectl get nodes --show-labels

    The output is similar to this:

    1. NAME      STATUS    ROLES    AGE     VERSION        LABELS
    2. worker0   Ready     <none>   1d      v1.13.0        ...,disktype=ssd,kubernetes.io/hostname=worker0
    3. worker1   Ready     <none>   1d      v1.13.0        ...,kubernetes.io/hostname=worker1
    4. worker2   Ready     <none>   1d      v1.13.0        ...,kubernetes.io/hostname=worker2

    In the preceding output, you can see that the worker0 node has a disktype=ssd label.

Create a pod that gets scheduled to your chosen node

This pod configuration file describes a pod that has a node selector, disktype: ssd. This means that the pod will get scheduled on a node that has a disktype=ssd label.

pods/pod-nginx.yaml

  1. apiVersion: v1
  2. kind: Pod
  3. metadata:
  4.   name: nginx
  5.   labels:
  6.     env: test
  7. spec:
  8.   containers:
  9.   - name: nginx
  10.     image: nginx
  11.     imagePullPolicy: IfNotPresent
  12.   nodeSelector:
  13.     disktype: ssd

  1. Use the configuration file to create a pod that will get scheduled on your chosen node:

    1. kubectl apply -f https://k8s.io/examples/pods/pod-nginx.yaml

  2. Verify that the pod is running on your chosen node:

    1. kubectl get pods --output=wide

    The output is similar to this:

    1. NAME     READY     STATUS    RESTARTS   AGE    IP           NODE
    2. nginx    1/1       Running   0          13s    10.200.0.4   worker0

Create a pod that gets scheduled to specific node

You can also schedule a pod to one specific node via setting nodeName.

pods/pod-nginx-specific-node.yaml

  1. apiVersion: v1
  2. kind: Pod
  3. metadata:
  4.   name: nginx
  5. spec:
  6.   nodeName: foo-node # schedule pod to specific node
  7.   containers:
  8.   - name: nginx
  9.     image: nginx
  10.     imagePullPolicy: IfNotPresent

Use the configuration file to create a pod that will get scheduled on foo-node only.

What’s next