Label-based filtering with kubectl in Kubernetes - Mini Project: Build & Apply

Label-based filtering with kubectl

📖 Scenario: You are managing a Kubernetes cluster with multiple pods running different applications. You want to filter and view pods based on their labels to quickly find specific groups of pods.

🎯 Goal: Learn how to use kubectl commands to filter pods by their labels and display the filtered list.

📋 What You'll Learn

Use kubectl commands to list pods

Filter pods by label selectors

Understand how to add labels to pods

Display filtered pods using kubectl

💡 Why This Matters

🌍 Real World

Filtering Kubernetes resources by labels helps quickly find and manage specific groups of pods or other objects in large clusters.

💼 Career

Kubernetes administrators and DevOps engineers use label-based filtering daily to monitor, troubleshoot, and organize cluster resources efficiently.

1

Create pods with labels

Create two pods named frontend-pod and backend-pod with labels app=frontend and app=backend respectively using kubectl run commands.

Kubernetes

# Create frontend-pod with label app=frontend
# Create backend-pod with label app=backend

Need a hint?

Use kubectl run with --labels option to assign labels when creating pods.

2

Add a label selector variable

Create a shell variable called LABEL_SELECTOR and set it to app=frontend to use as a filter for pods.

Kubernetes

kubectl run frontend-pod --image=nginx --labels=app=frontend
kubectl run backend-pod --image=nginx --labels=app=backend

# Set LABEL_SELECTOR variable to 'app=frontend'

Need a hint?

Use LABEL_SELECTOR=app=frontend to create the variable.

3

Filter pods using the label selector

Use kubectl get pods with the -l option and the variable $LABEL_SELECTOR to list only pods with the label app=frontend.

Kubernetes

kubectl run frontend-pod --image=nginx --labels=app=frontend
kubectl run backend-pod --image=nginx --labels=app=backend

LABEL_SELECTOR=app=frontend

# List pods filtered by label selector

Need a hint?

Use kubectl get pods -l $LABEL_SELECTOR to filter pods by label.

4

Display the filtered pods

Run the command to display pods filtered by the label app=frontend. The output should list only the frontend-pod.

Kubernetes

kubectl run frontend-pod --image=nginx --labels=app=frontend
kubectl run backend-pod --image=nginx --labels=app=backend

LABEL_SELECTOR=app=frontend

kubectl get pods -l $LABEL_SELECTOR

# Display the filtered pods output

Need a hint?

The output should show only the pod named frontend-pod.