What is Kubernetes LoadBalancer?

A LoadBalancer service is the standard way to expose a service to the outside. On cloud, this will spin up a Network Load Balancer that will give you a single IP address that will forward all traffic to your service.

If your Kubernetes cluster environment is on any cloud provider like google cloud, Azure, or AWS, then if you use the type load balancer, you will get an external IP from this provider on behalf of you. so you can access your application using the external IP provided by the provider that will forward the request to the pods. But is chargeable.

if you are using On-Premises BareMetal Kubernetes Environment then you need to use MetalLB for getting the load balancer external IP

A pure software solution: MetalLB

MetalLB provides a network load-balancer implementation for Kubernetes clusters that do not run on a supported cloud provider, effectively allowing the usage of LoadBalancer Services within any cluster.

This section demonstrates how to use the Layer 2 configuration mode of MetalLB together with the NGINX Ingress controller in a Kubernetes cluster that has publicly accessible nodes. In this mode, one node attracts all the traffic for the ingress-nginx Service IP.

Installation

Helm Add Repository and Update We will add the helm repository and then make sure that all of our repositories are up to date.

helm repo add metallb https://metallb.github.io/metallb
helm repo update

Basic configuration

$ cat values.yaml 
apiVersion: v1
kind: ConfigMap
metadata:
  namespace: metallb-system
  name: config
data:
  config: |
    address-pools:
    - name: default
      protocol: layer2
      addresses:
        - 192.168.100.120-192.168.100.130

kubectl apply -f  values.yaml

Load Balancer workflow diagram

First, we need to create a deployment

root@Kubernet-Master:~# cat deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:    #label name should be common in load balancer service  
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

root@Kubernet-Master:~#

kubectl apply -f  deployment.yaml

For checking the deployment status

kubectl get deployment

Load balancer Manifest file

root@Kubernet-Master:~# cat loadbalancer.yaml
apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: LoadBalancer
status:
  loadBalancer:

Apply the configuration

kubectl apply -f loadbalancer.yaml

For checking the service output

kubectl get svc

http://192.168.100.120

Hope you have got an idea about Kubernetes Load Balancer and why it is needed

Thank you !!!