Creating a Service in Kubernetes

 

What is a Service?

A Service is a Kubernetes object that provides a stable IP address and DNS name to access Pods.

Since Pod IP addresses can change when Pods are recreated, a Service acts as a fixed endpoint for accessing the application.

Why Do We Need a Service?

Suppose you have 3 Pods: Pod-1/Pod-2/Pod-3

If Pod-1 crashes, Kubernetes creates a new Pod with a different IP address.

Without a Service:

Users need to know individual Pod IPs.

Pod IPs keep changing.

With a Service:

Users connect to one stable IP/DNS.

The Service automatically forwards traffic to available Pods.

Service YAML Example

apiVersion: v1

kind: Service

metadata:

  name: nginx-service

spec:

  selector:

    app: nginx

  ports:

  - protocol: TCP

    port: 80

    targetPort: 80

  type: ClusterIP

Understanding the YAML

selector - The Service finds all Pods having (labels:  app: nginx)

selector:

  app: nginx

port - The port exposed by the Service.

port: 80

targetPort - The port on the container where the application is running.

targetPort: 80

type - Defines how the Service is exposed.

type: ClusterIP

How Service Works (The Service distributes incoming requests among all available Pods.)

nginx-service

|

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

|       |        |

Pod1   Pod2    Pod3

Create a Service

kubectl apply -f service.yaml

kubectl get svc

kubectl get services

Types of Services

1. ClusterIP (Default)

Accessible only inside the Kubernetes cluster.

type: ClusterIP

2. NodePort

Exposes the application on a port of every worker node. <Node-IP>:30000

type: NodePort

3. LoadBalancer

Creates an external load balancer (AWS, Azure, GCP). [Access: External IP]

type: LoadBalancer