Tasks

Step-by-step instructions for performing operations with Kubernetes.

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Assigning 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.

Adding a label to a node

  1. List the nodes in your cluster:

     kubectl get nodes
    

    The output is similar to this:

     NAME      STATUS    AGE     VERSION
     worker0   Ready     1d      v1.6.0+fff5156
     worker1   Ready     1d      v1.6.0+fff5156
     worker2   Ready     1d      v1.6.0+fff5156
    
  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    AGE     VERSION            LABELS
     worker0   Ready     1d      v1.6.0+fff5156     ...,disktype=ssd,kubernetes.io/hostname=worker0
     worker1   Ready     1d      v1.6.0+fff5156     ...,kubernetes.io/hostname=worker1
     worker2   Ready     1d      v1.6.0+fff5156     ...,kubernetes.io/hostname=worker2
    

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

Creating 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.

pod.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 create -f http://k8s.io/docs/tasks/administer-cluster/pod.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
    

What’s next

Learn more about labels and selectors.

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