railway-deployment

Railway Deployment Knowledge Base

Railway Platform Overview

Railway is a modern PaaS that deploys applications from Git repositories with automatic builds and deployments.

Key Concepts

• Project: Container for all services and environments
• Service: Individual deployable unit (backend, frontend, database)
• Environment: Isolated deployment target (staging, production)
• Deployment: Specific version of code running in an environment

Auto-Deploy Configuration

Railway automatically deploys when you push to configured branches:

Branch	Environment	Trigger
develop	Staging	Push to develop
main	Production	Push to main

Setting Up Auto-Deploy

1. Go to Railway Dashboard → Project → Settings
2. Under "Deployments", configure:
   • Source branch for each environment
   • Build command (auto-detected usually)
   • Start command

Project Structure Patterns

Monorepo (Multiple Services)

project/
├── frontend/
│   ├── Dockerfile
│   └── package.json
├── backend/
│   ├── Dockerfile
│   └── requirements.txt
└── railway.json

Single Service

project/
├── Dockerfile (or detected runtime)
├── package.json / requirements.txt
└── railway.json (optional)

railway.json Configuration

{
  "$schema": "https://railway.app/railway.schema.json",
  "build": {
    "builder": "DOCKERFILE",
    "dockerfilePath": "Dockerfile"
  },
  "deploy": {
    "numReplicas": 1,
    "healthcheckPath": "/health",
    "healthcheckTimeout": 300,
    "restartPolicyType": "ON_FAILURE"
  }
}

Dockerfile Best Practices for Railway

# Multi-stage build for smaller images
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM node:20-alpine AS runner
WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
EXPOSE 3000
CMD ["node", "dist/index.js"]

Python Example

FROM python:3.11-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
EXPOSE 8000
CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]

Environment Variables

Railway-Provided Variables

RAILWAY_ENVIRONMENT=production
RAILWAY_SERVICE_NAME=backend
RAILWAY_PROJECT_ID=xxx
PORT=<assigned port>

Common Application Variables

ENVIRONMENT=production
DATABASE_URL=postgresql://...
REDIS_URL=redis://...
API_KEY=xxx
CORS_ORIGINS=https://myapp.com

Health Checks

Railway performs health checks to ensure your app is running:

# FastAPI example
@app.get("/health")
async def health_check():
    return {"status": "healthy"}

// Express example
app.get('/health', (req, res) => {
  res.json({ status: 'healthy' });
});

Networking

Internal Networking

Services within the same project can communicate via internal DNS:

http://backend.railway.internal:8000

External Access

• Railway provides *.up.railway.app domains
• Custom domains can be configured in settings

Logging

Viewing Logs

# Via CLI
railway logs
railway logs --environment production
railway logs -n 100  # Last 100 lines

# Via Dashboard
Project → Service → Logs tab

Structured Logging Best Practices

import logging
import json

logging.basicConfig(
    format='%(message)s',
    level=logging.INFO
)

def log_json(level, message, **kwargs):
    log_entry = {"message": message, **kwargs}
    getattr(logging, level)(json.dumps(log_entry))

Scaling

Horizontal Scaling

// railway.json
{
  "deploy": {
    "numReplicas": 3
  }
}

Resource Limits

Configure in Railway Dashboard:

• Memory limit
• CPU limit
• Instance count

Database Connections

Connection Pooling

For production, use connection pooling:

# SQLAlchemy with pool
engine = create_engine(
    DATABASE_URL,
    pool_size=5,
    max_overflow=10,
    pool_pre_ping=True
)

Deployment Monitoring

Key Metrics to Watch

• Build time
• Deployment status
• Memory usage
• CPU usage
• Response times
• Error rates

Alerts

Configure alerts in Railway Dashboard for:

• Deployment failures
• High memory usage
• Service crashes

Rollback Procedures

Quick Rollback

1. Go to Railway Dashboard
2. Select service → Deployments
3. Click "Rollback" on previous healthy deployment

Git-Based Rollback

git revert HEAD
git push origin main
# Railway auto-deploys reverted code

Cost Optimization

• Use multi-stage Docker builds (smaller images)
• Set appropriate resource limits
• Use sleep/hibernation for staging if not needed 24/7
• Monitor usage in Railway Dashboard

Troubleshooting

Symptom	Check
Build fails	Dockerfile syntax, dependencies
Deploy hangs	Health check endpoint, startup time
502 errors	App not binding to PORT env var
Slow performance	Resource limits, database queries
Missing env vars	Railway Dashboard → Variables