Does PlanetScale Work With Fly.io?
PlanetScale and Fly.io work seamlessly together—deploy your app on Fly while using PlanetScale as your managed MySQL database, with excellent latency and zero infrastructure overhead.
Quick Facts
How PlanetScale Works With Fly.io
PlanetScale and Fly.io complement each other perfectly in a modern full-stack architecture. You deploy your application (Node.js, Python, Go, etc.) to Fly.io, which handles running your app close to users worldwide with automatic scaling and load balancing. Meanwhile, PlanetScale serves as your serverless MySQL database—you connect via standard MySQL drivers or ORMs like Prisma, TypeORM, or Sequelize. The connection string from PlanetScale works directly in Fly.io environment variables without any special configuration.
The developer experience is smooth: branch your database schema in PlanetScale for feature development, deploy your app to Fly.io, and both scale independently. PlanetScale's connection pooling handles concurrent connections from Fly instances across regions. Network latency is minimal since both are optimized for global distribution. The only consideration is that PlanetScale's free tier has connection limits (~100 concurrent), which may require a paid plan for high-traffic Fly deployments, but this scales linearly and predictably.
This combination is especially powerful because Fly.io's close-to-user deployment means your app logic runs regionally while your database queries benefit from PlanetScale's query optimization and automatic failover. You get the benefits of edge computing without database replication complexity.
Best Use Cases
Quick Setup
npm install prisma @prisma/client && npm install -D @types/node// 1. Set PlanetScale connection in fly.toml or via `flyctl secrets set DATABASE_URL='...'`
// 2. prisma/schema.prisma
generator client {
provider = "prisma-client-js"
}
datasource db {
provider = "mysql"
url = env("DATABASE_URL")
}
model User {
id Int @id @default(autoincrement())
email String @unique
name String?
}
// 3. app.ts (Express/Node.js example)
import { PrismaClient } from '@prisma/client';
const prisma = new PrismaClient();
app.get('/users', async (req, res) => {
const users = await prisma.user.findMany();
res.json(users);
});
// 4. Deploy
// flyctl deployKnown Issues & Gotchas
PlanetScale requires FOREIGN KEY constraints disabled by default, which some ORMs expect
Fix: Set `FOREIGN_KEY_CHECKS=ON` in your connection string or disable foreign key validations in your ORM config (e.g., Prisma's `referentialIntegrity = 'prisma'`)
Free tier PlanetScale has 100 concurrent connections; Fly.io can spawn many instances quickly
Fix: Use PlanetScale connection pooling or upgrade to a paid plan. Monitor connection usage with `SHOW PROCESSLIST`
Long-running database operations may timeout with default PlanetScale timeouts (10s for queries)
Fix: Optimize slow queries, use read replicas for reporting, or increase timeout via connection string parameters
PlanetScale connection string contains sensitive credentials that must be stored in Fly secrets
Fix: Use `flyctl secrets set DATABASE_URL='mysql://...'` to securely inject credentials into your app
Alternatives
- •Vercel + Supabase (PostgreSQL focus, tighter Next.js integration)
- •Railway + Railway Postgres (simpler, all-in-one deployment platform)
- •AWS EC2 + AWS RDS (more control, higher operational overhead)
Resources
Related Compatibility Guides
Explore more compatibility guides