AuctionApp - Production Django Auction Platform

A Django 5.1 auction platform with real-time bidding, deployed on Google Cloud Platform with production-grade infrastructure.

Live Demo: AuctionApp - link

---

🏗️ Production Architecture

Internet Request
    ↓
Nginx (Reverse Proxy)
    ├── Static file serving with far-future cache headers
    ├── Request buffering and SSL termination
    └── Unix socket proxy to ↓
    
Gunicorn (3 Workers)
    └── Forwards to ↓
    
Django Application
    └── Database connection via ↓
    
Cloud SQL Proxy
    ├── Encrypted tunnel (eliminates public DB IP)
    ├── IAM-based authentication
    └── Connects to Cloud SQL PostgreSQL

Key Architectural Decisions

Why Nginx as Reverse Proxy?

• Static files served directly without touching Django (70% bandwidth reduction)
• Request buffering prevents slow clients from blocking app workers
• Enables future horizontal scaling with load balancing

Why Cloud SQL Proxy?

• No public database IP needed (security layer)
• Automatic encryption without manual SSL certificate management
• Handles IAM authentication and automatic credential rotation
• Connection pooling and automatic reconnection on network issues

Why Unix Sockets over TCP?

• Lower latency (no TCP/IP stack overhead)
• Better performance for local inter-process communication
• Automatic access control via filesystem permissions

Why 3 Gunicorn Workers?

• Formula: (2 x CPU_cores) + 1 = optimal for e2-micro (1 vCPU)
• Balances concurrency with memory constraints
• Prevents resource exhaustion under load

---

🔐 Security Implementation

Infrastructure Security

• Cloud SQL Proxy Tunnel: Database connections never exposed to public internet
• GCP Secret Manager: Credentials stored encrypted, never in code or config files
• Systemd Process Isolation: Application runs as dedicated user (not root)
• Environment-based Configuration: Separation of dev/prod secrets via python-decouple

Application Security

• Rate Limiting on Bids: 10 bids/minute prevents auction manipulation
• Email Verification: Token-based confirmation with 24-hour expiration
• Self-bidding Prevention: Business logic enforces auction integrity
• Password Requirements: 8+ chars, mixed case, numbers, special characters enforced server-side

Production Settings

# Security headers automatically added in production
SECURE_SSL_REDIRECT = True
SESSION_COOKIE_SECURE = True
CSRF_COOKIE_SECURE = True
SECURE_HSTS_SECONDS = 31536000
X_FRAME_OPTIONS = 'DENY'

---

🚀 Deployment Stack

Infrastructure: GCP Compute Engine (e2-micro, Ubuntu 22.04) + Cloud SQL PostgreSQL 15
Web Stack: Nginx → Gunicorn (3 workers) → Django 5.1
Database Connection: Cloud SQL Proxy (encrypted tunnel)
Static Files: WhiteNoise (gzip compression, immutable caching)
Process Management: Systemd services with auto-restart
Email: SendGrid transactional email

---

📊 Technical Highlights

Database Architecture

PostgreSQL over SQLite for production:

• Proper concurrent access with row-level locking
• Connection pooling (CONN_MAX_AGE=600)
• Query optimization with indexes on frequently accessed fields
• ACID compliance for auction bid integrity

Static File Optimization

WhiteNoise Configuration:

• Automatic compression (reduces file sizes by ~70%)
• Immutable caching with far-future expiry headers
• Manifest-based versioning for cache busting
• No CDN required for medium traffic loads

Process Management

Systemd Service Architecture:

# Three automated services with dependency ordering
cloudsql-proxy.service (After=network.target)
    └── Provides database connectivity
gunicorn.service (After=network.target)
    └── Application server with auto-restart
nginx.service
    └── Reverse proxy and static serving

All services configured with Restart=always for automatic recovery from failures.

---

🔧 Key Technical Challenges Solved

1. Cloud SQL Proxy Configuration

Challenge: Service failing with exit code 2
Root Cause: Incompatible flag syntax between proxy versions
Solution: Updated to correct -instances=PROJECT:REGION:INSTANCE=tcp:5432 format, switched to TCP over Unix socket for reliability

2. PostgreSQL Schema Permissions

Challenge: Django migrations failing with "permission denied for schema public"
Solution: Granted schema ownership and default privileges:

ALTER SCHEMA public OWNER TO auction_user;
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT ALL ON TABLES TO auction_user;

3. Static File Delivery

Challenge: CSS/JS files returning 404 in production
Solution: Implemented WhiteNoise middleware and configured Nginx location blocks with proper aliasing and caching headers

---

🗃️ Database Schema Design

Core Models:

• Custom User Model (extends AbstractUser): Email verification workflow with token expiration
• Listing: Auction items with category relationships and active/inactive status
• Bid: Timestamped bid history with amount validation and highest bid tracking
• Watchlist: Many-to-many relationship for user favorites
• Notification: Winner alerts with read/unread status

Key Relationships:

• One-to-Many: User → Listings (owner)
• Many-to-Many: User ↔ Listings (watchlist)
• One-to-Many: Listing → Bids (history)
• Foreign Keys with on_delete=CASCADE for referential integrity

---

🎓 Technical Skills Demonstrated

Cloud Infrastructure

• GCP resource provisioning (Compute Engine, Cloud SQL, Secret Manager)
• Secure database connectivity with Cloud SQL Proxy
• Credential management and secret rotation
• Automated backup configuration

System Architecture

• Reverse proxy implementation and request routing
• WSGI server configuration and worker tuning
• Unix socket inter-process communication
• Systemd service orchestration

DevOps

• Linux server administration (Ubuntu)
• Service monitoring with journalctl
• Environment-based configuration management
• Production deployment workflows

---

🔮 Scalability Path

Current: Single VM with all components
Next Steps:

• Horizontal Scaling: Managed Instance Group with load balancer
• Caching Layer: Redis for session storage and query caching
• Background Tasks: Celery for async email sending
• Read Replicas: Cloud SQL read replicas for query distribution
• CDN: Cloud CDN for global static file distribution

---

👤 Author

Michal Pytel
GitHub | LinkedIn

Production Django deployment on Google Cloud Platform