How to setup load balancer with Elastic file system (EFS) in AWS? Part 2

5 min read. Apr 18, 2022

Hello folks, in this second part of the article of configuring load balancer with EFS, we’re going to configure a virtual private cloud and create subnetworks for the load balancer and servers behind it. A virtual private cloud helps to provide multiple layers of security by allowing us to enforce the access control list (ACL) on the subnetwork and security groups on the elastic load balancer and EC2 instances as I mentioned in the last article

The minimal configuration of the load balancer requires at least two EC2 instances in different availability zones for availability and scalability of the application. Similarly, AWS docs suggest creating at least one public subnet on each of the availability zones for the load balancer. Apart from that, we also need to create two private subnets for the two servers (EC2 instances) which serve the request for incoming traffic on the load balancer.

To sum up, we need to create a VPC with two public and private subnets. 

Setup VPC and subnet

In order to get to the VPC configuration wizard, you can either type “VPC” on the search bar or select VPC from the Services > All Services on the AWS dashboard. Then, click on Create VPC on the navigation pane. 

The following provides a summary of the steps from the AWS docs to configure VPC and subnets:

  1. Select VPC, subnets, etc. from the resource creation radio-options.
  2. Give a meaningful name to the VPC.
  3. Enter in the IPV4 CIDR block for the VPC. This gives us 4096 IP addresses and it should be more than enough to be divided between 4 subnets as AWS recommends only a minimum of 8 free IP addresses on the public subnets where the load balancer resides.
  4. Default options should be fine for the rest of the fields. 
IPV6 CIDR block: No IPv6 CIDR block 
Tenancy: Default
Availability Zones (AZs): 2
Number of public subnets: 2
Number of private subnets: 2
Number of public subnets: None
VPC endpoints: S3 gateway
DNS options: Enable DNS resolution

Lastly, click on the Create VPC button to create VPC and subnets.

AWS VPC and subnets configuration

AWS VPC and subnets configuration

Image: Screenshot of VPC and subnets configuration wizard

As you can see in the below screenshot, AWS evenly divides the IP addresses to each of  the subnets within the VPC. Similarly, the two public subnets, which are connected to the internet gateway share the same route table, however, each of the private subnets has a separate record on the route table.

Image: Preview of subnets, route tables and connections in VPC

Wrapping up

The steps to create VPC and subnets are quite straightforward on the AWS management console. In addition, AWS provides a fancy real-time visualization of subnets with associated route tables and network connections while creating VPC.