Multi-Stack DevOps Voting Application on AWS

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📖 Overview

This project demonstrates a complete end-to-end DevOps workflow by deploying a polyglot microservices voting application on AWS.

Users vote between Cats 🐱 and Dogs 🐶. The system processes votes asynchronously and displays real-time results.

The application is intentionally multi-language and multi-framework to showcase real-world polyglot infrastructure skills:

Service	Language / Framework	Role
Vote	Python + Flask	Frontend – accept votes
Result	Node.js + Express	Frontend – display live results
Worker	C# / .NET	Background worker
Redis	Redis	In-memory message queue
Postgres	PostgreSQL	Persistent data store

Infrastructure is fully managed as code using Terraform.
Configuration & deployment are automated with Ansible.
All application components run as Docker containers.

Goal: Production-style multi-tier architecture on AWS with proper networking, security groups, bastion host, and remote state management — ready for a professional GitHub portfolio.

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🏗️ Architecture

High-Level AWS Architecture

Key Components:

• VPC with Public and Private Subnets
• Bastion / Frontend EC2 (Public Subnet) – Vote + Result services + Jump Host
• Backend EC2 (Private Subnet) – Redis + Worker
• Database EC2 (Private Subnet) – PostgreSQL
• NAT Gateway – Outbound internet access for private instances
• Security Groups – Least-privilege rules between tiers
• Terraform Remote State – S3 + DynamoDB locking

Application Data Flow

User → Vote (Python) → Redis ← Worker (.NET) → PostgreSQL ← Result (Node.js) → User

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🛠️ Technology Stack

Category	Tools / Services
Cloud Provider	Amazon Web Services (AWS)
Infrastructure as Code	Terraform
Configuration Management	Ansible
Containerization	Docker & Docker Compose
Networking	VPC, Subnets, Route Tables, NAT Gateway, Security Groups, Bastion Host
Application Stack	Python (Flask), Node.js (Express), .NET Worker
Data Stores	Redis (queue), PostgreSQL (persistence)
CI / State	Terraform Remote Backend (S3 + DynamoDB)
Version Control	Git + GitHub

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✨ Key Features

• ✅ Multi-tier AWS architecture (Public + Private subnets)
• ✅ Infrastructure provisioned entirely with Terraform
• ✅ Configuration management & container deployment with Ansible
• ✅ Bastion host pattern for secure access to private instances
• ✅ Least-privilege Security Groups
• ✅ Dockerized polyglot microservices
• ✅ Redis as message queue + PostgreSQL for persistence
• ✅ Real-time voting results via WebSockets
• ✅ Remote Terraform state with locking
• ✅ Portfolio-ready documentation and architecture diagrams

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📁 Project Structure

.
├── terraform/                  # Infrastructure as Code
│   ├── main.tf
│   ├── variables.tf
│   ├── outputs.tf
│   ├── vpc.tf
│   ├── ec2.tf
│   ├── security_groups.tf
│   ├── backend.tf              # S3 + DynamoDB remote state
│   └── ...
├── ansible/                    # Configuration Management
│   ├── inventory/
│   ├── group_vars/
│   ├── playbooks/
│   │   ├── site.yml
│   │   ├── install_docker.yml
│   │   └── deploy_containers.yml
│   └── roles/
│       ├── docker_install/
│       ├── deploy_containers/
│       └── postgres_persist/
├── app/                        # Application source (or Docker images from Docker Hub)
│   ├── vote/
│   ├── result/
│   └── worker/
├── docs/
│   ├── architecture.png
│   └── app-architecture.jpg
├── docker-compose.yml          # Local development
└── README.md

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🚀 Getting Started

Prerequisites

• AWS Account with appropriate IAM permissions
• Terraform ≥ 1.5
• Ansible ≥ 2.14
• Docker & Docker Compose
• AWS CLI configured (aws configure)
• SSH key pair for EC2 access

1. Clone the Repository

git clone https://github.com/<your-username>/multi-stack-devops-voting-app.git
cd multi-stack-devops-voting-app

2. Provision Infrastructure (Terraform)

cd terraform
terraform init
terraform plan
terraform apply

This creates:

• VPC + Public/Private Subnets
• NAT Gateway
• 3 EC2 instances (Frontend/Bastion, Backend, Database)
• Security Groups
• Remote state backend (S3 + DynamoDB)

3. Configure Instances (Ansible)

Update inventory with private IPs / hostnames and configure SSH ProxyJump via the bastion.

cd ../ansible
ansible-playbook -i inventory/hosts playbooks/site.yml

The playbooks will:

1. Install & configure Docker
2. Pull images from Docker Hub
3. Deploy containers with correct environment variables
4. Persist PostgreSQL data on a volume

4. Access the Application

• Vote UI: http://<FRONTEND_PUBLIC_IP>:8080
• Result UI: http://<FRONTEND_PUBLIC_IP>:8081

Cast votes and watch results update in real time.

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🔐 Security Highlights

• Private subnets for Redis, Worker, and PostgreSQL (no direct internet exposure)
• Bastion host pattern for SSH access
• Security Groups enforce least privilege:
  • Frontend SG → Internet (HTTP)
  • Backend SG → Accept Redis traffic only from Frontend
  • DB SG → Accept Postgres traffic only from Worker/Backend
• Terraform remote state stored securely in S3 with DynamoDB locking
• No secrets committed to Git (use environment variables / Ansible Vault)

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🧪 Local Development (Optional)

docker compose up --build

Access:

• Vote → http://localhost:8080
• Result → http://localhost:8081

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📸 Demo & Presentation

This project is designed for a 15-minute portfolio presentation covering:

1. Terraform plan & infrastructure walkthrough
2. Ansible playbooks & roles
3. Live demo of voting + real-time results
4. Architecture diagram explanation
5. Security group & networking decisions

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🧠 What I Build

• Designing multi-tier VPC architectures (public/private subnets, NAT, route tables)
• Writing production-grade Terraform modules and remote state
• Using Ansible with jump hosts / ProxyJump for private instances
• Container networking across multiple EC2 hosts
• Least-privilege security group design
• Orchestrating polyglot microservices (Python, Node.js, .NET)
• End-to-end Infrastructure-as-Code + Configuration-as-Code workflow

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👤 Author

**Penchalaiah Jammula **

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📄 License

This project is for portfolio purposes.
Original application inspired by the Docker Sample Voting App.

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Built with ❤️ for DevOps Portfolio
AWS · Terraform · Ansible · Docker · Networking