Kubernetes Services

Cluster IP, Node Port, LoadBalancer, Headless Service

Think of Kubernetes Services as the receptionist in a big office building. Just like how the receptionist directs visitors to the right offices, Kubernetes Services directs incoming traffic to the right places (called Pods) in a Kubernetes cluster.

“Kubernetes Services are an essential component for enabling communication between different parts of an application running on a Kubernetes cluster.”

There are four types of Kubernetes services — ClusterIP, NodePort, LoadBalancer and ExternalName]

COMMANDS:

Create a Service: kubectl create -f service.yaml

Get Information about Services: kubectl get services

Describe a Service: kubectl describe service <service-name>

Delete a Service: kubectl delete service <service-name>

Edit a Service: kubectl edit service <service-name>

Check Service Endpoints: kubectl get endpoints <service-name>

Edit Service Endpoints: kubectl edit endpoints <service-name>

Expose a Deployment as a service : kubectl expose deployment <deployment-name> --type=NodePort --port=<port> --target-port=<target-port>

ClusterIP:

Cluster IP (By Default): Expose port Inside the cluster ( Provide Internal Connectivity )

Let’s create a service:

# Service 

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: my-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080

Deployment YAML File:

# Deployment 

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-container
          image: my-image:latest
          ports:
            - containerPort: 8080

Attaching service and Deployment to POD:

# Pod 

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
  labels:
    app: my-app
spec:
  containers:
    - name: my-container
      image: my-image:latest
      ports:
        - containerPort: 8080

NodePort:

NodePort: It enables access to the service from outside the cluster (Provides access to external traffic)

# service.yaml

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: my-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
  type: NodePort

# Pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
  labels:
    app: my-app
spec:
  containers:
    - name: my-container
      image: my-image:latest
      ports:
        - containerPort: 8080

LoadBalancer:

LoadBalancer provides internal and external connectivity

#Service.yaml

apiVersion: v1
kind: Service
metadata:
  name: my-loadbalancer-service
spec:
  selector:
    app: my-app
  ports:
    - protocol: TCP
      port: 80  # External connectivity: Exposes port 80 externally
      targetPort: 8080  # Internal connectivity: Forwards traffic to port 8080 on selected pods
  type: LoadBalancer  # External connectivity: Creates an external load balancer

Headless Service:

Headless service allows the client to directly communicate with the Pods. Do not assign IP to itself.

Headless Services are used in deploying Stateful Applications in Kubernetes.

#Service.yaml

apiVersion: v1
kind: Service
metadata:
  name: my-headless-service
spec:
  clusterIP: None  # Specifies that this is a headless service
  selector:
    app: my-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080

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