Added readme, deployment notes and architecture, and configured Host port in Docker compose

Author: Lavanya-GOW

README.md

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+# AWS Three-Tier Flask Application using Terraform, Docker & GitHub Actions
+
+## Overview
+
+This project demonstrates the deployment of a production-inspired three-tier application on AWS using Infrastructure as Code (Terraform), containerization (Docker), and CI/CD (GitHub Actions).
+
+The infrastructure is completely provisioned using Terraform and supports automatic scaling, load balancing, and secure networking.
+
+---
+
+## Tech Stack
+
+- AWS
+- Terraform
+- Docker
+- Docker Compose
+- GitHub Actions
+- Flask
+- Redis
+- PostgreSQL (RDS)
+- Auto Scaling Groups
+- Application Load Balancers
+- CloudWatch
+- IAM
+
+---
+
+## Architecture
+
+```
+Internet
+    │
+    ▼
+Internet Gateway
+    │
+    ▼
+External Application Load Balancer
+    │
+    ▼
+Frontend Auto Scaling Group
+    │
+    ▼
+Internal Application Load Balancer
+    │
+    ▼
+Backend Auto Scaling Group
+    │
+    ▼
+Amazon RDS PostgreSQL
+```
+
+Infrastructure also includes:
+
+- Bastion Host
+- NAT Gateway
+- Public and Private Subnets
+- Route Tables
+- IAM Roles
+- CloudWatch Alarms
+- Security Groups
+- Remote Terraform State
+
+---
+
+## Features
+
+- Infrastructure as Code
+- Highly Available Architecture
+- Multi-AZ Deployment
+- Automatic Scaling
+- Internal & External Load Balancing
+- CI/CD Pipelines
+- Dockerized Application
+- Bastion Host Access
+- Secure Private Networking
+- Remote Terraform Backend
+
+---
+
+## Repository Structure
+
+```
+.
+├── terraform_infra/
+│   ├── main.tf
+│   ├── variables.tf
+│   ├── outputs.tf
+│   ├── backend.tf
+│   ├── scripts/
+│   └── ...
+│
+├── .github/
+│   └── workflows/
+│       ├── docker_pipeline.yml
+│       ├── terraform_pipeline.yml
+│       ├── terraform_apply.yml
+│       └── terraform_destroy.yml
+│
+├── Dockerfile
+├── docker-compose.yml
+├── app.py
+├── requirements.txt
+└── README.md
+```
+
+---
+
+## GitHub Actions
+
+This repository contains four workflows.
+
+### Docker Pipeline
+
+- Build Docker image
+- Push to DockerHub
+- Smoke Test
+
+### Terraform Pipeline
+
+- fmt
+- validate
+- plan
+
+### Terraform Apply
+
+Manual Deployment
+
+### Terraform Destroy
+
+Manual Infrastructure Cleanup
+
+---
+
+## Deployment
+
+```bash
+terraform init
+terraform plan
+terraform apply
+```
+
+or
+
+Run the GitHub Actions workflow:
+
+Terraform Apply
+
+---
+
+## Future Improvements
+
+- Kubernetes Migration
+- Helm Charts
+- ArgoCD
+- Monitoring using Prometheus
+- Grafana
+- EKS Deployment
+- Service Mesh
+
+---
+
+## Author
+
+Built by Lavanya as part of a Cloud/DevOps learning journey.

architecture.md

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+# Infrastructure Architecture
+
+## Components
+
+### Networking
+
+- VPC
+- Internet Gateway
+- NAT Gateway
+- Elastic IP
+- Public Subnet
+- Frontend Private Subnets
+- Backend Private Subnets
+- Database Private Subnets
+- Route Tables
+
+---
+
+### Security
+
+- Security Groups
+- IAM Roles
+- IAM Instance Profiles
+- Bastion Host
+
+---
+
+### Compute
+
+Frontend Layer
+
+- Launch Template
+- Auto Scaling Group
+- Docker
+- Flask
+
+Backend Layer
+
+- Launch Template
+- Auto Scaling Group
+- Docker
+- Flask API
+
+---
+
+### Load Balancers
+
+External ALB
+
+Receives traffic from Internet
+
+↓
+
+Routes traffic to Frontend ASG
+
+Internal ALB
+
+Receives traffic from Frontend
+
+↓
+
+Routes traffic to Backend ASG
+
+---
+
+### Database
+
+Amazon RDS PostgreSQL
+
+Private Subnet
+
+---
+
+### CI/CD
+
+GitHub
+
+↓
+
+GitHub Actions
+
+↓
+
+Docker Build
+
+↓
+
+DockerHub
+
+↓
+
+Terraform Apply
+
+↓
+
+EC2 User Data
+
+↓
+
+Docker Compose Pull
+
+↓
+
+Application Starts
+
+---
+
+## Request Flow
+
+```
+User
+
+↓
+
+External ALB
+
+↓
+
+Frontend ASG
+
+↓
+
+Internal ALB
+
+↓
+
+Backend ASG
+
+↓
+
+RDS
+```
+
+---
+
+## Availability
+
+- Multi Availability Zone
+- Auto Scaling
+- Health Checks
+- Target Groups
+- CloudWatch Monitoring
+
+---
+
+## Security
+
+- Bastion Host
+- Private EC2
+- Private Database
+- IAM Roles
+- Security Groups