by To understand the Kubernetes services, lets create a simple image, that you can use to understand and experiment with ClusterIP, LoadBalancer, and NodePort services in Kubernetes. For simplicity, Let’s create a simple Node.js web server for this purpose..
Create a Node.js web server::
Create a file namedserver.jswith the following content:
package main
const http = require('http');
const port = 3000;
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/plain');
res.end('Hello, Kubernetes!\n');
});
server.listen(port, () => {
console.log(`Server running at http://localhost:${port}/`);
});
Create a Dockerfile:
FROM node:alpine
WORKDIR /app
COPY server.js .
EXPOSE 3000
CMD [“node”, “server.js”]
Build the Docker image:
Open a terminal in the directory where your Dockerfile and server.js are located, and run:
docker build -t simple-node-server .
2. Deployment YAML:
Create a Deployment YAML file (deployment.yaml):
package main
apiVersion: apps/v1
kind: Deployment
metadata:
name: example-deployment
spec:
replicas: 3
selector:
matchLabels:
app: example-app
template:
metadata:
labels:
app: example-app
spec:
containers:
- name: web-server
image: simple-node-server
Apply the deployment:
kubectl apply -f deployment.yaml
Service YAML for ClusterIP (service-clusterip.yaml):
package main
apiVersion: v1
kind: Service
metadata:
name: example-service-clusterip
spec:
selector:
app: example-app
ports:
- protocol: TCP
port: 80
targetPort: 3000
type: ClusterIP
Apply the ClusterIP service:
kubectl apply -f service-clusterip.yaml
Service YAML for NodePort (service-nodeport.yaml):
package main
apiVersion: apps/v1
apiVersion: v1
kind: Service
metadata:
name: example-service-nodeport
spec:
selector:
app: example-app
ports:
- protocol: TCP
port: 80
targetPort: 3000
type: NodePort
Apply the NodePort service:
kubectl apply -f service-nodeport.yaml
Service YAML for LoadBalancer (service-loadbalancer.yaml):
package main
apiVersion: v1
kind: Service
metadata:
name: example-service-loadbalancer
spec:
selector:
app: example-app
ports:
- protocol: TCP
port: 80
targetPort: 3000
type: LoadBalancer
Apply the LoadBalancer service:
kubectl apply -f service-loadbalancer.yaml
Now, you have a simple web server deployed in Kubernetes with different service types (ClusterIP, NodePort, and LoadBalancer). You can access them based on the service type and experiment with the behavior.
