How to Setup AWS Application Load Balancer

2020/2/44 min read

This blog will show how to create an AWS application load balancer with custom VPC's EC2 instances.

Setup Custom VPC

Create VPC

Go to VPC and click create VPC, enter the VPC field as below example.

Name tag: enter your VPC name
IPv4 CIDR block: enter your CIDR block IP range
IPv6 CIDR block: choose IPv6
Network Border Group
Tenancy: Default (you can choose if you want to single-tenant, dedicated hardware or not)

Create Subnet

We'll need 2 subnets to create the Application Load Balancer.

Name tag: enter any name
VPC: choose the VPC just created
Availability Zone: choose the availability zone
IPv4 CIDR block: 172.0.1.0/24
IPv6 CIDR block: don't assign IPv6 (don't need IPv6 for this blog)

Create the second subnet, for creating Application Load balancer, you'll need at least 2 subnets.

set auto-assign IP, so EC2 instance will get the public IP address.

Create Internet Gateway

Create an internet gateway and attach the custom VPC.

Setup Route Table

Create a route table for the subnet

associate subnet to the route table

set route table to use the internet gateway for internet, enter the routes as following

Destination: 0.0.0.0/0 (for IPv4 Access)

Target: choose the Internet gateway

Now, VPC setup is done, we can use this custom VPC to create your own EC2.

Setup EC2

We'll set up EC2 with simple Php code, let's leave everything as a default setting and create 2 EC2 Instance.

Choose AMI (For example, choose Amazon AMI)
Choose General Purpose: t2.micro
Configure Instance Details

Network: choose the VPC just created
Subnet: choose the subnet just created
Leave everything as default
Put following to User Data field, this will start PHP simple site.

#!/bin/bash
yum update -y
yum install httpd -y
chkconfig httpd on
service httpd start
cd /var/www/html
echo "hi, server-01" > index.html

Configure Security Group

add port 80 so it will be accessible from the browser.

Now, let's create another EC2 instance. Setup everything as the first one, except the User data, change to server-02 as following

#!/bin/bash
yum update -y
yum install httpd -y
chkconfig httpd on
service httpd start
cd /var/www/html
echo "hi, server-02" > index.html

Create Target Groups

Let's create a target group for Application Load Balancer, this blog only trying to set up HTTP only.

Target type choose Instances
Enter any name for the target group name
Protocol - Http - 80
Choose the VPC
Health checks

Enter the path

Choose available instances
Click Create Target Group
Creating a target is done and associated with a list of instances.

Create Registered targets

Click registered targets and add EC2 instance by choose 2 EC2 instance and click include as pending

Create Application Load Balancer

Click Create Load Balancer
Choose Application Load Balancer
Enter Name
Use default Http - 80
Choose VPC
Choose subnet (here you'll need at least 2 subnet)
Choose Security Groups
Configure Routing (here, select the target group created earlier)
Now, Load Balancer is creating
Should be able to see application load between 2 instances

After Application Load Balancer become active, copy the dns name to the browser you should see the site will change between the two server.Now, this is how you can simple provision application load balancer with AWS.

AWS VPC