Creating Pods with kubectl in Kubernetes - Visual Walkthrough

Process Flow - Creating Pods with kubectl

Write Pod YAML file

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Run kubectl apply -f pod.yaml

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kubectl sends request to API Server

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API Server validates and stores Pod spec

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Scheduler assigns Pod to a Node

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Kubelet on Node creates container

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Pod status changes to Running

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kubectl get pods shows Pod status

This flow shows how writing a Pod definition, applying it with kubectl, and Kubernetes components work together to create and run a Pod.

Execution Sample

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: my-container
    image: nginx

This YAML defines a Pod named 'my-pod' running an nginx container.

Process Table

Step	Action	Command/Operation	Result/Output
1	Write Pod YAML file	Create pod.yaml with Pod spec	File pod.yaml created with Pod definition
2	Apply Pod YAML	kubectl apply -f pod.yaml	Pod 'my-pod' created in Kubernetes cluster
3	API Server receives request	API Server validates Pod spec	Pod object stored in etcd
4	Scheduler assigns Pod	Scheduler selects a Node	Pod assigned to Node 'node-1'
5	Kubelet creates container	Kubelet pulls nginx image and starts container	Container running on Node
6	Pod status update	Pod status changes to Running	kubectl get pods shows STATUS=Running
7	Verify Pod	kubectl get pods	NAME READY STATUS RESTARTS AGE my-pod 1/1 Running 0 1m

💡 Pod is running successfully; kubectl get pods confirms the Pod status as Running.

Status Tracker

Variable	Start	After Step 2	After Step 4	After Step 6	Final
Pod Object	Not created	Created in cluster	Assigned to Node 'node-1'	Container running	Pod Running
Pod Status	None	Pending	Pending	Running	Running

Key Moments - 3 Insights

Why does the Pod status show 'Pending' before it becomes 'Running'?

After applying the Pod YAML (Step 2), the Pod object exists but the scheduler has not assigned it to a Node yet (Step 4). During this time, the status is 'Pending' as Kubernetes prepares to run it.

What does 'kubectl apply -f pod.yaml' actually do?

It sends the Pod definition to the Kubernetes API Server which validates and stores it (Step 3). This command does not create the container directly but triggers the cluster to create the Pod.

How do we know the Pod is successfully running?

The final 'kubectl get pods' command (Step 7) shows the Pod with STATUS=Running and READY=1/1, meaning the container inside the Pod is up and running.

Visual Quiz - 3 Questions

Look at the execution table, at which step does the Pod get assigned to a Node?

A Step 3

B Step 4

C Step 5

D Step 6

💡 Hint

Check the 'Action' column for 'Scheduler assigns Pod' in the execution table.

According to the variable tracker, what is the Pod status after Step 2?

A Succeeded

B Running

C Pending

D Failed

💡 Hint

Look at the 'Pod Status' row under 'After Step 2' in the variable tracker.

If the container image was incorrect, which step would most likely fail?

A Step 5 - Kubelet creates container

B Step 3 - API Server validation

C Step 2 - Apply Pod YAML

D Step 7 - kubectl get pods

💡 Hint

Refer to the 'Kubelet creates container' action in Step 5 where the image is pulled and container started.

Concept Snapshot

Creating Pods with kubectl:
- Write Pod YAML file defining apiVersion, kind, metadata, spec
- Run 'kubectl apply -f pod.yaml' to send Pod spec to cluster
- API Server validates and stores Pod object
- Scheduler assigns Pod to a Node
- Kubelet on Node pulls image and starts container
- Pod status changes from Pending to Running
- Use 'kubectl get pods' to check Pod status

Full Transcript

To create a Pod in Kubernetes, you first write a YAML file describing the Pod's details like its name and container image. Then you run 'kubectl apply -f pod.yaml' which sends this definition to the Kubernetes API Server. The API Server checks the Pod spec and stores it. Next, the Scheduler picks a Node to run the Pod. The Kubelet on that Node pulls the container image and starts the container. The Pod status changes from Pending to Running once the container is up. You can verify the Pod is running by using 'kubectl get pods' which shows the Pod's status and readiness.