Deno Deploy

Deploy your Rails app globally on Deno’s edge network with serverless databases.

Table of Contents

• Overview
• Prerequisites
• Database Options
• Deployment
• Manual Deployment
• Generated Files
  • main.ts
  • deno.json
• Environment Variables
• Real-Time Features
• Local Development
• Troubleshooting
  • “Module not found” errors
  • Database connection errors
  • Permission errors
• Comparison with Vercel Edge
• Limitations
• Resources

Overview

Deno Deploy runs your application as serverless functions on Deno’s global edge network. Like Vercel Edge, it provides fast cold starts and automatic scaling.

Use cases:

• Global applications needing low latency
• Pay-per-request pricing
• Automatic scaling
• Deno/TypeScript native environment

Prerequisites

1. Deno CLI

   # macOS
   brew install deno
   
   # Or via curl
   curl -fsSL https://deno.land/install.sh | sh
   

2. deployctl CLI

   deno install -Arf jsr:@deno/deployctl
   

3. Deno Deploy account
   • Sign up at dash.deno.com
   • Create a new project
4. Create database — Choose one:
   • Neon — Serverless PostgreSQL
   • Turso — SQLite at the edge
   • PlanetScale — Serverless MySQL
   • Supabase — Full backend platform

Database Options

All use HTTP protocols that work in edge environments (no TCP sockets).

See Database Overview for detailed setup guides.

Deployment

# Prepare database (migrate, seed if fresh)
bin/juntos db:prepare -d neon

# Deploy
bin/juntos deploy -t deno-deploy -d neon

The deploy command:

1. Builds the app with Deno Deploy configuration
2. Generates main.ts entry point and deno.json
3. Verifies the build loads correctly
4. Runs deployctl deploy

Manual Deployment

If you prefer manual control:

# Build only
bin/juntos build -t deno-deploy -d neon

# Deploy with deployctl
cd dist
deployctl deploy --project=myapp main.ts

Generated Files

main.ts

// Deno Deploy entry point
import { Application, Router } from './lib/rails.js';
import './config/routes.js';
import { migrations } from './db/migrate/index.js';
import { Seeds } from './db/seeds.js';
import { layout } from './app/views/layouts/application.js';

Application.configure({
  migrations: migrations,
  seeds: Seeds,
  layout: layout
});

Deno.serve(Application.handler());

deno.json

{
  "name": "myapp",
  "tasks": {
    "start": "deno run --allow-net --allow-env --allow-read main.ts"
  }
}

Environment Variables

Set these in Deno Deploy Dashboard → Project Settings → Environment Variables:

For local development, create .env.local:

# .env.local
DATABASE_URL=postgres://user:pass@host/db

Real-Time Features

Like Vercel, Deno Deploy can’t maintain native WebSocket connections across requests. For Turbo Streams broadcasting, Juntos uses:

• Supabase Realtime — If using Supabase as your database
• Pusher — For other databases (Neon, Turso, PlanetScale)

# Supabase: real-time included
bin/juntos deploy -t deno-deploy -d supabase

# Other databases: add Pusher credentials
bin/juntos deploy -t deno-deploy -d neon

For Pusher, add environment variables:

PUSHER_APP_ID=123456
PUSHER_KEY=abc123
PUSHER_SECRET=xyz789
PUSHER_CLUSTER=us2

Local Development

Test locally before deploying:

cd dist
deno task start

Or use Deno’s built-in server:

deno run --allow-net --allow-env --allow-read main.ts

Troubleshooting

“Module not found” errors

Deno uses URL imports. Ensure all dependencies are available:

# Check imports resolve
deno check main.ts

Database connection errors

1. Verify environment variables are set in Deno Deploy
2. Check database is accessible (no IP restrictions)
3. Ensure SSL mode is correct for your database

Permission errors

Deno is secure by default. The entry point needs:

• --allow-net — Network access for database and HTTP
• --allow-env — Read environment variables
• --allow-read — Read local files

Comparison with Vercel Edge

Both use V8 Isolates for fast cold starts and global distribution. Choose Deno Deploy if you prefer the Deno ecosystem (built-in TypeScript, URL imports, secure-by-default permissions).

Limitations

• No filesystem writes — Use object storage
• No native WebSockets — Use Pusher, Supabase Realtime, or Ably
• Request timeout — 50 second limit on Deno Deploy
• Cold starts — First request after idle may be slower

Resources

• Deno Deploy Documentation
• deployctl Reference
• Deno Deploy Pricing