Does PostgreSQL Work With Fly.io?
PostgreSQL runs seamlessly on Fly.io as a managed database or self-hosted service, making it an excellent choice for full-stack applications deployed globally.
Quick Facts
How PostgreSQL Works With Fly.io
Fly.io provides native PostgreSQL support through two primary approaches: Fly Postgres (a managed offering) and self-hosted PostgreSQL using standard Docker containers. Fly Postgres handles replication, backups, and high availability out-of-the-box, while self-hosting gives you more control at the cost of operational overhead. Your application runs in Fly machines distributed globally, and database connections are automatically routed through Fly's private networking layer, eliminating the need to expose PostgreSQL publicly. The developer experience is straightforward—you provision a database via the Fly CLI, receive a connection string, and configure your application environment variables. Since everything runs on Fly's infrastructure, you get sub-millisecond latency between your app and database, and data residency compliance is simplified since you control which region hosts your database.
Best Use Cases
Quick Setup
npm install pg dotenvimport { Pool } from 'pg';
import dotenv from 'dotenv';
dotenv.config();
const pool = new Pool({
connectionString: process.env.DATABASE_URL,
max: 10,
idleTimeoutMillis: 30000,
});
async function getUsers() {
const result = await pool.query('SELECT id, email FROM users LIMIT 10');
return result.rows;
}
// Deploy with: flyctl deploy
// Set DATABASE_URL via: flyctl secrets set DATABASE_URL=postgres://...
getUsers().then(console.log).catch(console.error);Known Issues & Gotchas
Connection pooling required for apps spawning many short-lived processes
Fix: Use PgBouncer in transaction pooling mode or a connection pool like node-postgres with max 10-20 connections per Fly machine
Cross-region latency impacts write-heavy workloads if database isn't in your primary region
Fix: Co-locate Fly app instances with the primary database region; use read replicas for secondary regions
Managed Fly Postgres has limited customization for PostgreSQL configuration parameters
Fix: Use self-hosted PostgreSQL in a Fly machine if you need advanced tuning like custom GUC settings
Network costs for cross-region database replication can accumulate
Fix: Monitor egress; consider read replicas only in regions with significant traffic
Alternatives
- •Supabase + Fly.io: Managed PostgreSQL with built-in auth, real-time subscriptions, and Edge Functions
- •PlanetScale (MySQL) + Fly.io: For applications preferring MySQL with serverless scaling
- •MongoDB Atlas + Fly.io: Document database alternative if relational structure isn't required
Resources
Related Compatibility Guides
Explore more compatibility guides