Network Load Balancer (NLB) in AWS - Mini Project: Build & Apply

Create a Network Load Balancer (NLB) with AWS CDK

📖 Scenario: You are setting up a simple Network Load Balancer (NLB) in AWS to distribute incoming TCP traffic to backend servers. This is a common task when you want to improve availability and scalability of your application.

🎯 Goal: Build an AWS CDK stack that creates a Network Load Balancer with one listener on port 80 and a target group with two IP targets.

📋 What You'll Learn

Create a Network Load Balancer named myNLB in the default VPC

Add a listener on port 80 for TCP protocol

Create a target group named myTargetGroup with TCP protocol on port 80

Add two IP targets with IP addresses 10.0.0.10 and 10.0.0.11 to the target group

💡 Why This Matters

🌍 Real World

Network Load Balancers are used to distribute TCP traffic efficiently to backend servers, improving availability and scalability of applications.

💼 Career

Understanding how to configure NLBs with AWS CDK is important for cloud engineers and developers managing scalable network architectures.

1

Create the Network Load Balancer

Create a Network Load Balancer called myNLB in the default VPC using AWS CDK. Use the NetworkLoadBalancer construct from @aws-cdk/aws-elasticloadbalancingv2 and set internetFacing to true.

AWS

import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
import * as elbv2 from 'aws-cdk-lib/aws-elasticloadbalancingv2';

export class NlbStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const vpc = ec2.Vpc.fromLookup(this, 'DefaultVPC', { isDefault: true });

    // Create a Network Load Balancer called myNLB in the default VPC
    // Your code here
  }
}

Need a hint?

Use new elbv2.NetworkLoadBalancer(this, 'myNLB', { vpc, internetFacing: true }) to create the NLB.

2

Add a listener on port 80

Add a listener to the Network Load Balancer myNLB on port 80 using TCP protocol. Use the addListener method with port: 80 and protocol: elbv2.Protocol.TCP.

AWS

import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
import * as elbv2 from 'aws-cdk-lib/aws-elasticloadbalancingv2';

export class NlbStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const vpc = ec2.Vpc.fromLookup(this, 'DefaultVPC', { isDefault: true });

    const myNLB = new elbv2.NetworkLoadBalancer(this, 'myNLB', {
      vpc,
      internetFacing: true
    });

    // Add a listener on port 80 with TCP protocol
    // Your code here
  }
}

Need a hint?

Use myNLB.addListener('Listener', { port: 80, protocol: elbv2.Protocol.TCP }) to add the listener.

3

Create a target group with TCP protocol

Create a target group called myTargetGroup with TCP protocol on port 80 in the default VPC. Use the NetworkTargetGroup construct from @aws-cdk/aws-elasticloadbalancingv2.

AWS

import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
import * as elbv2 from 'aws-cdk-lib/aws-elasticloadbalancingv2';

export class NlbStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const vpc = ec2.Vpc.fromLookup(this, 'DefaultVPC', { isDefault: true });

    const myNLB = new elbv2.NetworkLoadBalancer(this, 'myNLB', {
      vpc,
      internetFacing: true
    });

    const listener = myNLB.addListener('Listener', {
      port: 80,
      protocol: elbv2.Protocol.TCP
    });

    // Create a target group called myTargetGroup with TCP protocol on port 80
    // Your code here
  }
}

Need a hint?

Use new elbv2.NetworkTargetGroup(this, 'myTargetGroup', { vpc, port: 80, protocol: elbv2.Protocol.TCP }) to create the target group.

4

Add IP targets to the target group and attach to listener

Add two IP targets with IP addresses 10.0.0.10 and 10.0.0.11 to the target group myTargetGroup. Then attach myTargetGroup to the listener listener using the addTargetGroups method.

AWS

import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
import * as elbv2 from 'aws-cdk-lib/aws-elasticloadbalancingv2';

export class NlbStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const vpc = ec2.Vpc.fromLookup(this, 'DefaultVPC', { isDefault: true });

    const myNLB = new elbv2.NetworkLoadBalancer(this, 'myNLB', {
      vpc,
      internetFacing: true
    });

    const listener = myNLB.addListener('Listener', {
      port: 80,
      protocol: elbv2.Protocol.TCP
    });

    const myTargetGroup = new elbv2.NetworkTargetGroup(this, 'myTargetGroup', {
      vpc,
      port: 80,
      protocol: elbv2.Protocol.TCP
    });

    // Add IP targets 10.0.0.10 and 10.0.0.11 to myTargetGroup
    // Attach myTargetGroup to listener
    // Your code here
  }
}

Need a hint?

Use myTargetGroup.addTarget(new elbv2.IpTarget('10.0.0.10', 80)) and similarly for the second IP. Then attach with listener.addTargetGroups('TargetGroupAttachment', { targetGroups: [myTargetGroup] }).