Pod lifecycle states in Kubernetes - Commands & Configuration

Introduction

Pods are the smallest units in Kubernetes that run containers. Understanding their lifecycle states helps you know what is happening to your app at each step, like when it starts, runs, or stops.

When you want to check if your app is running correctly inside Kubernetes.

When your pod is stuck and you need to know why it is not starting.

When you want to monitor the health and status of your app containers.

When you need to debug issues related to pod crashes or restarts.

When you want to understand how Kubernetes manages your app's containers over time.

Commands

This command creates a pod named example-pod running the nginx container. The restart=Never flag means Kubernetes will not restart the pod automatically if it stops.

Terminal

kubectl run example-pod --image=nginx --restart=Never

Expected Output

pod/example-pod created

→

--image - Specifies the container image to run inside the pod

→

--restart - Controls the pod restart policy; Never means no automatic restart

This command shows the current state of the example-pod, such as Pending, Running, or Completed.

Terminal

kubectl get pods example-pod

Expected Output

NAME          READY   STATUS    RESTARTS   AGE

example-pod   1/1     Running   0          10s

This command gives detailed information about the pod, including events and state changes, helping you understand its lifecycle transitions.

Terminal

kubectl describe pod example-pod

Expected Output

Name:         example-pod

Namespace:    default

Status:       Running

Containers:

  nginx:

    Container ID:   docker://abcdef123456

    Image:          nginx

    State:          Running

      Started:      Thu, 01 Jan 1970 00:00:10 +0000

Events:

  Type    Reason     Age   From               Message

  ----    ------     ----  ----               -------

  Normal  Scheduled  1m    default-scheduler  Successfully assigned default/example-pod to node-1

  Normal  Pulled     1m    kubelet            Container image "nginx" already present on machine

  Normal  Created    1m    kubelet            Created container nginx

  Normal  Started    1m    kubelet            Started container nginx

This command deletes the example-pod, which moves it to the Terminating state before removal.

Terminal

kubectl delete pod example-pod

Expected Output

pod "example-pod" deleted

Key Concept

If you remember nothing else from pod lifecycle states, remember: pods move through states like Pending, Running, and Terminating to show their current condition.

Common Mistakes

Trying to create a pod without specifying a container image

Kubernetes needs a container image to run inside the pod; without it, the pod cannot start.

Always specify a valid container image using the --image flag when creating a pod.

Assuming a pod is running just because it exists

A pod can exist but be in Pending or Failed state, meaning it is not ready to serve your app.

Use kubectl get pods and check the STATUS column to confirm the pod is Running.

Deleting a pod without understanding it will be Terminating first

The pod does not disappear instantly; it goes through Terminating state which may take time if cleanup is needed.

Wait for the pod to fully terminate before assuming it is gone.

Summary

Create a pod with kubectl run specifying the container image and restart policy.

Check the pod's current lifecycle state with kubectl get pods.

Use kubectl describe pod to see detailed state changes and events.

Delete the pod to move it to the Terminating state before removal.