Three Tier Architecture

AWS Three Tier Architecture Reference

This is an implementation of the classic three tier architecture for application hosting.
Three modules that constructs our architecture:

• network
• web
• db

How to deploy

Setup:

• Install Terraform
• Setup your credentials via AWS Provider
• Run Three Tier Init with the corresponding env value to setup terraform backend with s3 bucket and dynamodb
• Clone this project

Run commands to deploy:

• export env=dev (or prod)
• terraform get -update=true
• terraform init -backend-config=config/backend-${env}.conf -backend=true
• terraform apply -var-file=config/${env}.tfvars -var password=<db password> -lock=true

Learn more about Terraform commands here

Configuration files

There are two example configuration files in the config/ folder. Each contains inputs for the main terraform module to run.

• dev: for development environment settings
• prod: for production like environment settings

Main terraform module inputs

Name	Description	Type	Default	Required
allocated_storage	The amount of allocated storage	string	-	yes
db_subnet_b_cidr	The cidr range for db subnet b	string	-	yes
db_subnet_c_cidr	The cidr range for db subnet c	string	-	yes
instance_class	RDS instance class (e.g. db.t2.micro or db.m4.xlarge)	string	-	yes
multi_az	Create a replica in different zone if set to true	string	-	yes
password	RDS password	string	-	yes
private_subnet_b_cidr	The cidr range for private subnet b	string	-	yes
private_subnet_c_cidr	The cidr range for private subnet c	string	-	yes
public_subnet_b_cidr	The cidr range for public subnet b	string	-	yes
public_subnet_c_cidr	The cidr range for public subnet c	string	-	yes
skip_final_snapshot	Creates a snapshot when db is deleted if set to true	string	-	yes
username	RDS username	string	-	yes
vpc_cidr	The cidr range for vpc	string	-	yes

Outputs

Name	Description
elb_dns	Elastic Load Balancer DNS
rds_endpoint	RDS endpoint

References

• https://github.com/BWITS/terraform-best-practices#run-terraform-from-docker-container
• https://github.com/terraform-community-modules
• https://opencredo.com/terraform-infrastructure-design-patterns/
• https://github.com/terraform-providers/terraform-provider-aws/tree/master/examples/rds
• https://github.com/gruntwork-io/terragrunt-infrastructure-modules-example

CI/CD support

• Three Tier CI CD