3-Tier Application Deployment on Linux

This repository contains step-by-step instructions for deploying a 3-tier web application across three Linux virtual machines:

1. Web Tier – Nginx reverse proxy
2. Application Tier – Python Flask app served by Gunicorn
3. Database Tier – PostgreSQL

The documentation is split into sections for easier navigation.

📂 Documentation Sections

Section	File	Description
0 & 1 – Topology & Common Preparation	common.md	Network layout, IP assignments, and base setup for all VMs.
2 – Database VM Setup	database.md	Install and configure PostgreSQL, create database, user, and schema.
3 – Application VM Setup	app.md	Deploy Flask app with Gunicorn, configure systemd service, connect to DB.
4 – Web VM Setup	nginx.md	Configure Nginx reverse proxy to forward requests to the App tier.
5 – Verification & Troubleshooting	verification.md	End-to-end testing and debugging tips.

🗂 Directory Structure

.
├── README.md        # Main index (this file)
├── common.md        # Section 1
├── database.md      # Section 2
├── app.md           # Section 3
├── nginx.md         # Section 4
└── verification.md  # Section 5

🚀 Quick Start

1. Follow common.md to prepare all VMs.
2. Configure the database.md on the DB VM.
3. Deploy the app.md on the App VM.
4. Set up the nginx.md on the Web VM.
5. Run tests from verification.md to ensure everything works.

🔗 Related

• All steps assume RHEL/Rocky/AlmaLinux 9 or similar.
• SELinux is kept enforcing.
• Firewalld is used for network security.

If you’d like, I can also make this README.md include direct GitHub-style section anchors so clicking a link jumps directly to a section in the respective file. That makes it even easier for students to navigate. Would you like me to do that?