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. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

• Katacoda
• Play with Kubernetes

Add a label to a node

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

   kubectl get nodes --show-labels
   

   The output is similar to this:

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

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

   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:

   kubectl get nodes --show-labels
   

   The output is similar to this:

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

apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    env: test
spec:
  containers:
  - name: nginx
    image: nginx
    imagePullPolicy: IfNotPresent
  nodeSelector:
    disktype: ssd

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

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

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

   kubectl get pods --output=wide
   

   The output is similar to this:

   NAME     READY     STATUS    RESTARTS   AGE    IP           NODE
   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

apiVersion: v1
kind: Pod
metadata:
  name: nginx
spec:
  nodeName: foo-node # schedule pod to specific node
  containers:
  - name: nginx
    image: nginx
    imagePullPolicy: IfNotPresent

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

What's next

• Learn more about labels and selectors.
• Learn more about nodes.