Service selectors and labels in Kubernetes - Mini Project: Build & Apply

Service selectors and labels

📖 Scenario: You are managing a Kubernetes cluster for a small online store. You want to organize your pods and services so that the services can find the right pods using labels and selectors.

🎯 Goal: Learn how to create pods with labels and a service that selects those pods using matching labels.

📋 What You'll Learn

Create pods with specific labels

Create a service with a selector matching the pod labels

Verify the service selects the correct pods

💡 Why This Matters

🌍 Real World

Labels and selectors help organize and manage groups of pods in Kubernetes. Services use selectors to route traffic to the right pods automatically.

💼 Career

Understanding labels and selectors is essential for Kubernetes administrators and DevOps engineers to deploy and maintain scalable applications.

1

Create pods with labels

Create two pod YAML definitions named pod1.yaml and pod2.yaml. Each pod should have the label app: webstore. Use the image nginx for both pods.

Kubernetes

# Create pod1.yaml with label app: webstore
# Create pod2.yaml with label app: webstore

Need a hint?

Use metadata.labels to add labels to pods. Both pods must have the label app: webstore.

2

Create a service with a selector

Create a service YAML definition named service.yaml that selects pods with the label app: webstore. Use the service type ClusterIP and expose port 80.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: pod1
  labels:
    app: webstore
spec:
  containers:
  - name: nginx
    image: nginx
---
apiVersion: v1
kind: Pod
metadata:
  name: pod2
  labels:
    app: webstore
spec:
  containers:
  - name: nginx
    image: nginx

# Create service.yaml with selector app: webstore, type ClusterIP, port 80

Need a hint?

Use spec.selector to match the label app: webstore. Set spec.type to ClusterIP and expose port 80.

3

Verify the service selects the pods

Write the kubectl command to list pods selected by the service webstore-service using the label selector app=webstore.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: pod1
  labels:
    app: webstore
spec:
  containers:
  - name: nginx
    image: nginx
---
apiVersion: v1
kind: Pod
metadata:
  name: pod2
  labels:
    app: webstore
spec:
  containers:
  - name: nginx
    image: nginx
---
apiVersion: v1
kind: Service
metadata:
  name: webstore-service
spec:
  selector:
    app: webstore
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: ClusterIP

# Write the kubectl command to list pods with label app=webstore

Need a hint?

Use kubectl get pods -l app=webstore to list pods with the label app=webstore.

4

Display the pods selected by the service

Run the command kubectl get pods -l app=webstore and print the output exactly as it appears.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: pod1
  labels:
    app: webstore
spec:
  containers:
  - name: nginx
    image: nginx
---
apiVersion: v1
kind: Pod
metadata:
  name: pod2
  labels:
    app: webstore
spec:
  containers:
  - name: nginx
    image: nginx
---
apiVersion: v1
kind: Service
metadata:
  name: webstore-service
spec:
  selector:
    app: webstore
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: ClusterIP

# Print the output of kubectl get pods -l app=webstore

Need a hint?

The output shows the pods with label app=webstore selected by the service.