Service discovery via DNS in Kubernetes - Mini Project: Build & Apply

Service discovery via DNS in Kubernetes

📖 Scenario: You are working with a Kubernetes cluster where multiple microservices need to find each other to communicate. Kubernetes provides a built-in DNS service that allows pods to discover services by their names.In this project, you will create a simple Kubernetes Service and a Pod that uses DNS to discover that Service by its name.

🎯 Goal: Build a Kubernetes Service named my-service and a Pod named my-pod that uses DNS to discover my-service by its name and prints the resolved IP address.

📋 What You'll Learn

Create a Kubernetes Service named my-service exposing port 80

Create a Pod named my-pod with a container running busybox

Configure the Pod to resolve my-service using DNS

Print the resolved IP address of my-service inside the Pod

💡 Why This Matters

🌍 Real World

In real Kubernetes clusters, services need to find each other by name to communicate. DNS-based service discovery is a core feature that makes microservices talk easily.

💼 Career

Understanding Kubernetes service discovery is essential for DevOps engineers and cloud-native developers to deploy and manage scalable applications.

1

Create a Kubernetes Service named my-service

Write a YAML manifest to create a Kubernetes Service named my-service that exposes port 80 and targets pods with label app: myapp. Use ClusterIP as the service type.

Kubernetes

# Write the YAML manifest for the Service named my-service
# Your code here

Need a hint?

Use kind: Service and specify metadata.name as my-service. The selector should match pods labeled app: myapp. Expose port 80.

2

Create a Pod named my-pod with label app: myapp

Write a YAML manifest to create a Pod named my-pod with label app: myapp. The Pod should run a busybox container that sleeps for 3600 seconds.

Kubernetes

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: myapp
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: ClusterIP

# Write the YAML manifest for the Pod named my-pod
# Your code here

Need a hint?

Use kind: Pod with metadata.name as my-pod. Add label app: myapp. Use busybox image and command sleep 3600.

3

Add a command in the Pod to resolve my-service using DNS

Modify the busybox container command in my-pod to run nslookup my-service to resolve the service DNS name, then sleep for 3600 seconds.

Kubernetes

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: myapp
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: ClusterIP
---
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
  labels:
    app: myapp
spec:
  containers:
  - name: busybox
    image: busybox
    # Change the command to run nslookup my-service then sleep
    # Your code here

Need a hint?

Use command: ["sh", "-c", "nslookup my-service && sleep 3600"] to run DNS lookup and then keep the container alive.

4

Print the resolved IP address of my-service inside the Pod

Run the Pod and check the logs to see the output of nslookup my-service which shows the IP address resolved by Kubernetes DNS.

Kubernetes

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: myapp
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: ClusterIP
---
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
  labels:
    app: myapp
spec:
  containers:
  - name: busybox
    image: busybox
    command: ["sh", "-c", "nslookup my-service && sleep 3600"]

# Run 'kubectl logs my-pod' to see the IP address output
# Your code here

Need a hint?

Use kubectl logs my-pod to see the output of nslookup my-service which includes the IP address.