Use the Private Network

A live demo comparing the latency of connecting colocated services on Railway with private networking versus the public internet.

🌐 Live Demo: use-the-private-network.up.railway.app

Overview

This project demonstrates the performance benefits of using Railway's private networking feature. When you colocate services on Railway, you can connect them using private networking, which is:

• Faster - Lower latency by avoiding the public internet
• More Secure - Services communicate over an isolated private network
• Cost-Effective - No egress fees for data transfer between services

How It Works

This is a full-stack TanStack Start application that:

1. Runs a series of database queries (10 iterations) using both private and public network connections
2. Measures latency metrics for each connection type:
   • Server ↔ Database query latency
   • Total round-trip time
3. Calculates and displays statistical comparisons:
   • Average latency
   • Median latency
   • 95th percentile (p95) latency
4. Visualizes the results with interactive bar charts

Both the application and PostgreSQL database run in the same US-East (Virginia, USA) region on Railway.

Architecture

Technology Stack

• Framework: TanStack Start - Full-stack React framework
• Runtime: Bun
• Styling: Tailwind CSS
• Database: PostgreSQL
• Charts: Recharts
• State Management: TanStack Query

Project Structure

src/
├── routes/
│   ├── index.tsx                    # Main landing page with test UI
│   └── api/
│       ├── compare-latency.tsx      # Private network endpoint
│       └── compare-latency-public.tsx # Public network endpoint
├── lib/
│   └── db/
│       └── index.ts                 # Database connection configs
└── components/                      # UI components

Database Connections

The app uses two separate database connections:

• Private Network: DATABASE_URL - Uses Railway's private networking (internal connection)
• Public Network: DATABASE_PUBLIC_URL - Uses the public internet connection

Both connections query the same PostgreSQL database but take different network paths.

Getting Started

Prerequisites

• Bun installed
• A Railway account (sign up at railway.com)
• A PostgreSQL database on Railway

Local Development

1. Clone the repository:

git clone <repository-url>
cd use-the-private-network

2. Install dependencies:

bun install

3. Set up environment variables:

# Create a .env file with:
DATABASE_URL=postgresql://...              # Private network connection string. As a workaround, you can use the public connection string here for testing purposes.
DATABASE_PUBLIC_URL=postgresql://...       # Public connection string

4. Run the development server:

bun run dev

5. Open http://localhost:3000 in your browser

Understanding the Results

When you run the latency test, you'll see:

Metrics Explained

• Server ↔ Database: The time it takes for a query to execute on the database
• Round-Trip Time: The total time including network overhead and API processing
• Average: Mean latency across all queries
• Median: Middle value when all latencies are sorted
• p95: 95th percentile - 95% of queries are faster than this value

Expected Results

Typically, the private network connection will show:

• ✅ Lower latency (often 30-50% faster)
• ✅ More consistent performance (lower variance)
• ✅ Better p95 values

The public network connection may be affected by:

• Internet routing delays
• Geographic distance (even within the same region)
• Network congestion
• Additional security layers

Related Links

• Railway Private Networking Documentation
• TanStack Start Documentation
• Railway Platform

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Deployed on Railway 🚄