Three-Tier-Architecture

Architecture

This network architecture has three subnet tiers split across three availability zones. The web subnets also have a VPC routing table that will provide it access to the internet. The application and database tiers will not have such access; their routing tables will only allow internal network communication.

Prerequisites

• An AWS Account with an IAM user capable of creating resources – AdminstratorAccess
• A locally configured AWS profile for the above IAM user
• Terraform installation - steps
• AWS EC2 key pair - steps
• Environment Variables for AWS CLI - steps
• tfupdate installation - steps
• tfsec installation - steps

How to Apply/Destroy

This section details the deployment and teardown of the three-tier-architecture. Warning: this will create AWS resources that costs money

Deployment Steps

1. Clone the repo

git clone https://github.com/BJWRD/three-tier-architecture && cd three-tier-architecture

2. Update the s3 bucket name to your own - versions.tf

backend "s3" {
  bucket = "ENTER HERE"
  key    = "terraform.tfstate"
  region = "eu-west-2"
}

3. Update versions.tf

tfupdate terraform versions.tf && tfupdate provider aws versions.tf

4. Access the relevant environment

cd dev

NOTE: The environment you choose is dependent on whether you plan to provision resources which are adequate for a dev/stage/prod environment.

5. Initialise the TF directory

terraform init

5. Ensure the terraform code is formatted and validated

terraform fmt && terraform validate

6. tfsec - vulnerability check

tfsec

7. Create an execution plan

terraform plan

8. Execute terraform configuration

terraform apply --auto-approve

Verification Steps

1. Check AWS Infrastructure

Check the infrastructure deployment status, by enter the following terraform command -

 terraform show

NOTE: You may want to ouput terraform show to a .txt file for easier viewing i.e. terraform show > tf_infrastructure.txt

Alternatively, log into the AWS Console and verify your AWS infrastructure deployment from there.

VPC Verification

EC2 Verification

RDS Verification

2. Verify bjwrd/app.py webapp is running via Docker

SSH onto one of the EC2 hosts and verify that the bjwrd/app.py docker container is running -

docker ps

Alternatively, you can retrieve the ALB DNS address and search within your browser.

Teardown Steps

1. Destroy the deployed AWS Infrastructure

terraform destroy --auto-approve

Requirements

Name	Version
terraform	~>1.3.9
aws	~>3.50.0

Providers

Name	Version
aws	~>3.50.0

Modules

Name	Source
vpc	three-tier-architecture/modules/vpc
ec2	three-tier-architecture/modules/ec2
rds	three-tier-architecture/modules/rds

Resources

Name	Type
aws_launch_template	resource
aws_db_instance	resource
aws_vpc	resource
aws_subnet	resource
aws_internet_gateway	resource
aws_route_table	resource
aws_route_table_association	resource
aws_lb	resource
aws_lb_listener	resource
aws_lb_target_group	resource
aws_autoscaling_group	resource
aws_db_subnet_group	resource
aws_security_group	resource