Skip to main content
Welcome to this lesson on manually scheduling pods in Kubernetes. This guide explains how to assign pods to nodes without relying on Kubernetes’ built-in scheduler. Manual scheduling can be useful in niche scenarios where you need tighter control over pod placement. In this article, we review a basic pod manifest, demonstrate how manual scheduling works, and show you how to use binding objects to reassign pods if necessary.

​
Understanding the Default Scheduler Behavior

Every pod definition includes a field called nodeName, which is left unset by default. The Kubernetes scheduler automatically scans for pods without a nodeName and selects an appropriate node by updating this field and creating a binding object. Consider the basic pod manifest below: 
apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    name: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 8080
Typically, you do not include the nodeName field in your manifest. The scheduler uses this field only after selecting a node for the pod.

​
Manually Setting the Node Name

To manually assign a pod to a specific node during creation, populate the nodeName field in the manifest. For example, to schedule the pod on a node called “node02”, update your manifest as follows: 
apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    name: nginx
spec:
  nodeName: node02
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 8080
After creating the pod with this manifest, check its status with: 
kubectl get pods
Sample output before the scheduler assigns the IP: 
NAME    READY   STATUS    RESTARTS   AGE
nginx   0/1     Pending   0          3s
And after the pod becomes ready: 
kubectl get pods
NAME      READY   STATUS    RESTARTS   AGE   IP         NODE
nginx     1/1     Running   0          9s    10.40.0.4  node02
The nodeName must be set during pod creation. Once the pod is running, Kubernetes does not permit modifications to the nodeName field.

​
Reassigning a Running Pod Using a Binding Object

If a pod is already running and you need to change its node assignment, you cannot modify its nodeName directly. In this scenario, you can create a binding object that mimics the scheduler’s behavior.
  1. Create a binding object that specifies the target node (“node02”): 
    apiVersion: v1
kind: Binding
metadata:
  name: nginx
target:
  apiVersion: v1
  kind: Node
  name: node02
  2. The original pod definition remains unchanged: 
    apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    name: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    ports:
    - containerPort: 8080
  3. Convert the YAML binding to JSON (e.g., save it as binding.json) and send a POST request to the pod’s binding API using curl: 
    curl --header "Content-Type: application/json" --request POST --data @binding.json http://$SERVER/api/v1/namespaces/default/pods/nginx/binding
This binding instructs Kubernetes to assign the existing pod to the specified node without altering its original manifest.

​
Quick Reference Table

MethodUse CaseExample Snippet Reference
Direct AssignmentSet nodeName during pod creationSee manifest with nodeName: node02
Using a Binding ObjectReassign a running podSee binding object example

​
Additional Resources

That’s it for this lesson. Experiment with manually scheduling pods to solidify your understanding of Kubernetes node assignments. Happy scheduling!

Watch Video

Practice Lab