Deploy Prisma Postgres apps to Fly.io

Fly.io is a cloud application platform that lets you deploy full-stack applications globally. This guide shows you how to deploy a Node.js application using Prisma Postgres to Fly.io.

Prerequisites

A Fly.io account
The Fly CLI installed
An existing application using Prisma Postgres (see Quickstart)

Deploy your application

1. Generate Prisma Client in `postinstall`

Ensure your package.json includes a postinstall script to generate Prisma Client during deployment:

package.json

{
  // ...
  "scripts": {
    // ...
    "postinstall": "prisma generate"
  }
}

2. Launch your app with Fly.io

From your project directory, run:

fly launch

Follow the prompts to configure your application. Fly.io will auto-detect your Node.js application and create the necessary configuration.

3. Set your database connection string

Add your Prisma Postgres DATABASE_URL as a secret in Fly.io:

fly secrets set DATABASE_URL="your-prisma-postgres-connection-string"

You can find your DATABASE_URL in your .env file or in the Prisma Console.

4. Deploy

If not already deployed during fly launch, deploy your application:

fly deploy

Once the deployment completes, you'll see a success message with your app's URL:

🎉  SUCCESS! Your app is live and ready to use!  🎉

Visit: https://your-app-name.fly.dev/

In the Fly.io dashboard, your app's status may show as "Pending" initially. It typically transitions to "Deployed" within a few minutes.

Additional considerations

Ensure your project uses the correct environment variable

Ensure that the data source in your prisma.config.ts file is configured to use the DATABASE_URL environment variable:

prisma.config.ts

import "dotenv/config";
import { defineConfig, env } from "prisma/config";

export default defineConfig({
  datasource: {
    url: env("DATABASE_URL"),
  },
  schema: "./prisma/schema.prisma",
});

Running migrations in production

To run migrations on your deployed Fly.io app, you can use:

fly ssh console -C "npx prisma migrate deploy"

Or add a release command to your fly.toml:

fly.toml

[deploy]
  release_command = "npx prisma migrate deploy"

Scaling and regions

Fly.io lets you scale and place your application in multiple regions. For optimal performance, deploy your app in a region close to your Prisma Postgres database region.

fly scale count 2 --region iad

Troubleshooting

Prisma schema not found or Client not generated correctly

If you're using a custom Dockerfile and your build fails because the Prisma Client cannot be found, it's likely due to one of two reasons:

Order of operations: npm install (which runs postinstall) runs before the schema is copied.
Incorrect copy path: The schema is copied to the root instead of the prisma folder.

Solution: In your Dockerfile, copy the prisma/ directory to ./prisma before running npm install:

# ❌ Wrong order or path
COPY package*.json ./
COPY prisma .                   # Copies contents to root (wrong structure)
RUN npm install                 # postinstall runs but might fail or generate in wrong place

# ✅ Correct order and path
COPY package*.json ./
COPY prisma ./prisma            # Copies to ./prisma folder (preserves structure)
RUN npm install                 # postinstall finds schema in expected location
COPY . .

Fly.io