ecs-terraform-terragrunt

This repository contains terraform code to deploy a simple ghost api container on ECS Fargate cluster with an application load balancer and autoscaling group

Methodology

I am using terraform and terragrunt for expressing the infrastructure resources in AWS cloud.
terraform is used to express resources in the cloud using its aws provider whereas terragrunt is being used to keep the terraform code clean and dry of configuration.
I would be creating all resources, including VPC and subnets, routing and internet gateways, so that a dedicated, isolated environment can be established for the task.
terragrunt allows a single click deployment of all terraform code, using terragrunt run-all apply that can detect changes in the terragrunt configuration and apply the diff.
terragrunt allows code to be organised in a heirarchical manner so that resources can be organised.

Prerequisites

NOTE: These instructions are for Linux

aws: v2.0

sudo apt install unzip
curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
unzip awscliv2.zip
sudo ./aws/install

terraform: v1.2.1

sudo apt-get update && sudo apt-get install -y gnupg software-properties-common curl
curl -fsSL https://apt.releases.hashicorp.com/gpg | sudo apt-key add -
sudo apt-add-repository "deb [arch=amd64] https://apt.releases.hashicorp.com $(lsb_release -cs) main"
sudo apt-get update && sudo apt-get install terraform==1.2.1

terragrunt: v0.37.1

TERRAGRUNT_VERSION=0.37.1
wget https://github.com/gruntwork-io/terragrunt/releases/download/v$TERRAGRUNT_VERSION/terragrunt_linux_amd64
chmod +x terragrunt_linux_amd64
mv terragrunt_linux_amd64 /usr/local/bin/terragrunt

Infrastructure deployment and testing

Please configure your aws credentials by running aws configure after installing the cli utility.
After that, please cd into the terragrunt/ folder, and execute, terragrunt run-all apply command. terragrunt with the help of terraform would detect that the configuration was never applied and would print out a plan of deployment. Please enter y followed by enter to proceed. It will take few minutes for the entire deployment to be complete.
The application load balancer DNS name acts as a test-endpoint for the deployment. The DNS endpoint, alb_url, is emitted as an output during the aws_alb deployment.
Please copy the DNS endpoint and enter it in a browser, followed by the port, 80 in the format, alb_url:80.

Folder Structure

Folder structure of my code is as follows:

├── README.md
├── terraform
│   ├── aws_alb
│   │   ├── main.tf
│   │   ├── outputs.tf
│   │   └── variables.tf
│   ├── ecs_application
│   │   ├── main.tf
│   │   ├── outputs.tf
│   │   └── variables.tf
│   ├── ecs_cluster
│   │   ├── main.tf
│   │   ├── outputs.tf
│   │   └── variables.tf
│   └── vpc_subnet_module
│       ├── main.tf
│       ├── outputs.tf
│       └── variables.tf
└── terragrunt
    ├── base-infrastructure
    │   ├── dev
    │   │   ├── aws_alb
    │   │   │   └── terragrunt.hcl
    │   │   ├── ecs_application
    │   │   │   └── terragrunt.hcl
    │   │   ├── ecs_cluster
    │   │   │   └── terragrunt.hcl
    │   │   ├── stage.hcl
    │   │   └── vpc_subnet_module
    │   │       └── terragrunt.hcl
    │   └── staging
    ├── root-config.hcl
    └── terragrunt.hcl

Every terraform resource has a corresponding terragrunt.hcl configuration stored in terragrunt folder. This allows all resources to be created and configured indepenedently of each other.
In this project, we created resources only for a dev environment. We can always extend this project for other environments (staging and production) by creating their respective terragrunt configurations.

Code for ecs_application does not belong in base_infrastructure rather in a application folder at the same level as base_infrastructure. This would have looked as follows:

|── terragrunt
├── applications
│   └── ecs_application
│       └── terragrunt.hcl
├── base-infrastructure
│   ├── dev
│   │   ├── aws_alb
│   │   │   └── terragrunt.hcl
│   │   ├── ecs_cluster
│   │   │   └── terragrunt.hcl
│   │   ├── stage.hcl
│   │   └── vpc_subnet_module
│   │       └── terragrunt.hcl
│   └── staging
├── root-config.hcl
└── terragrunt.hcl

I was unable to do this during the challenge because i was running under time constraint after resolving an annoying issue on the way.

Future improvements

pre-commit hook could be installed and configured to format and lint the code (terragrunt hclfmt and terraform fmt -recursive) before committing it to the git repo.
The code can be tested for validity, using terragrunt validate prior to being pushed into the git repo.
This project could be set to have its own domain, which can be registered using AWS Route53. This domain can serve as a static endpoint through which the ghost application can be reached directly.
The project could be set to be available at HTTPS endpoint, using an SSL certificate generated by AWS Certificate Manager against the domain issued via the Route53
Automated autoscaling of tasks could be configured using aws_appautoscaling_target and aws_appautoscaling_policy resources.
A dockerfile for the application could be added to the terragrunt/applications/ecs_application folder which would be built, using docker provider and deployed to Fargate.

gqadonis / ecs-terraform-terragrunt Goto Github PK