Three tier architecture on AWS

Demo project for deploying a 3 tier architecture on AWS. You can use the code into this repository to deploy a demo application in a fault tolerant and high available manner.

Overview

The picture below represents the architecture we will deploy:

We will install a web server, an application server and a db server in each EC2. The instances span across 3 different Availability Zones to ensure a certain degree of fault tolerance and high availability. The DB will be a Mongo deployed as a replica set, and the db engine itself will take care of the synchronization across the 3 AZs.

Project structure

The code is organized in several folders. Here a brief description of each one.

• network: this folder contains a terraform module used to deploy all the network resoruces needed by the application, such as VPC, subnets, route tables etc...
• infra: in this folder there is a module used to deploy the infrastructure resources over the network built. We use this module to deploy EC2, Elastic Load Balancer etc...
• config: here we store all the configuration managment part. In particular, there are 3 Ansible playbooks used to configure, respectively a database (Mongo), an application server (NGINX Unit) and a web server (NGINX)
• src: this folder contains the real web server and application server source code, nothing more complex than two Flask application with a trivial RESTful API.
• deploy: this last folder contains all the utility scripts (Bash and Python) that can be used to automatically deploy all the infrastructure and start or stop the EC2 instances

For further details, every folder contains a README.md.

Quick deploy

If you do not change the structure of this repo, deploying the project is pretty simple.

NOTE: you should have an AWS account. All the resources deployed are included in the Free Tier but make sure to destroy everything when you are done!

Prerequisites

You need to install in your system the following tools/packages/whatever they are called:

• Ansible
• Terraform
• Python 3.X
• AWS CLI

You need also to configure a credentials file for the AWS CLI, read here

Deploy

NOTE: The architecture deployed will be open to the world. If you want to restrict access to the application, change the varibale values in main.tf. To understand the meaning of each value, take a look at the README.md into infra and network folders

IMPORTANT: substitute the id_rsa.pub file with your id_rsa.pub. Without doing this, Ansible will not be able to connect to the instance and configure them

You need to position into the deploy folder > cd deploy OPTIONAL: create a python virtual environment, to avoid conflicts and let your system clean

> python3 -m venv venv
> source ./venv/bin/activate

Install the required python packages

(venv)> pip install -r requirements

Modify the provider.tf variables according to you preferences. I suggest to change only shared_credentials_file and profile values. For more information, read here

Now you are ready to deploy!

(venv)> ./deploy.sh <your_aws_profile> <aws_region_name>

Test

It simple as cd deploy && ./tests.sh :)

Destroy Everything!!

Once you have finished, run the following command: terraform destroy --auto-approve