Hashicorp Terraform AWS VPC Module

Terraform AWS VPC Module by Source4Learn(An Opensource learning community.)

AWS VPC Module

This AWS Terraform module is designed to implement the common AWS infrastructure patterns such as single or multi-tier. The multi-tier patterns allow users to create infrastructure in separate layers as per the needs of modern applications.

AWS VPC Module will create following resources:

• VPC and Subnets
• Route Tables
• Security Gruoups
• Internet Gateway
• NAT Gateway
• Elatic IPs
• Network ACLs
• VPC Endpoints

Usage

provider "aws" {
  region = "ap-south-1"
}

module "vpc" {
  source                = "source4learn/vpc/aws"
  version               = "0.1.1"
  cluster_prefix        = "source4learn"
  cluster_environment   = "development"
  cluster_architecture  = "3-tier"
  cidr                  = "10.0.0.0/20"
  subnet_bits           = "4"
}

AWS Multi Layer Architecture

The AWS resources created in the public layers can be accessed publicly(i.e. - frontend servers, load-balancers, bastion instances, etc) but backed resources such as application servers, databases, caching servers will remain in private sections.

The AWS infrastructure patterns can be categories as follows:

• Public Layer: This layer consists of public subnets and has one subnet on each availability zone for high availability.
• Application Layer: This layer of AWS infrastructure contains the private subnets and one on each Availability Zone.
• Database Layer: The third layer consists of 3 private subnets and the same subnet on each availability zone.

Let's take a brief overview of multi-layers or multi-tier architecture. It divides the AWS infrastructure into layers like - Public, Private, and Storage(Isolated database) layers. The reason behind this implementation is to protect and isolate private layers from any unwanted public access. In other words, the Public layer provides a shield to internal layers of architecture.

To split the AWS infrastructure into multiple tiers and availability zones, please refer to below architectural diagram:

AWS allows users to create the multi-tier infrastructure and distribute it across the availability zones of the current region to achieve the high availability of resources.

3-tier architecture

A three-tier architecture pattern will help users to design a highly secured, modular, scalable, and fault-tolerant infrastructure. In this approach, the application infrastructure will be divided into a public layer, business logic, and storage layer. The resources in the individual layer are being created separately and they can communicate with specific pre-defined routes and security rules.

Use this approach while users needs to implement a microservices-based application architecture. The internet-facing services like - Frontend servers and bastion instances can be created public layer, app servers can be created in the intermediate application layer, and storage layer can have data services such as databases/caching etc.

This AWS Terraform module will help you to create an AWS VPC with 3-tier by just passing cluster_architecture as 3-tier. Users also need to define the desired VPC size in form of cidr and subnet mask as subnet_bits.

Example: Let's assume that the user needs to create a VPC network with ~4000 hosts available and each subnet should have 254 IP addresses. So the cidr value for vpc would be x.x.x.x/20 and the expected value for subnet would be x.x.x.x/24. But in this Terraform module, it accepts subnet mask value as subnet bits which can be calculated by subtracting the subnet cidr value with vpc cidr value.

cluster_architecture  = "3-tier"
cidr                  = "10.0.0.0/20"
subnet_bits           = "4"

2-tier architecture

The two-tier pattern is suitable for that application architecture which requires the isolation between the presentation and business logic without increasing the complexity of application infrastructure.

cluster_architecture  = "2-tier"
cidr                  = "10.0.0.0/20"
subnet_bits           = "4"

1-tier architecture

This single tier architecture can be used for monolythic infrastructures(Highly in-secure) and test/devlopment environments.

cluster_architecture  = "1-tier"
cidr                  = "10.0.0.0/20"
subnet_bits           = "4"

Requirements

Name	Version
terraform	>= 0.12.0

Providers

Name	Version
aws	n/a

Modules

Name	Source	Version
nat_gateway	./modules/nat-gateways
private_subnet	./modules/subnets
public_subnet	./modules/subnets
security_group	./modules/security-groups

Resources

Name	Type
aws_internet_gateway.igw	resource
aws_vpc.vpc	resource

Inputs

Name	Description	Type	Default	Required
cidr	CIDR block value to define the size of the AWS VPC	string	"10.0.0.0/20"	yes
cluster_architecture	To apply generic cluster architecture to AWS VPC Resources	string	n/a	yes
cluster_environment	To apply generic environment to AWS VPC Resources	string	n/a	yes
cluster_prefix	To apply generic naming to AWS VPC Resources	string	n/a	yes
subnet_bits	Subnet bits for cidrsubnet interpolation or Size we need to define for the Subnet (cidr of VPC + Subnet bits)	string	n/a	yes

Outputs

Name	Description
vpc_id	Terraform Output

Summary

If you encounter an error or problem in this setup, please report in the GitHub repository issues.
Reach us in case you need any further assistance.

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