## Introduction

[Bun](https://bun.sh) is a fast JavaScript runtime that includes a bundler, test runner, and package manager. In this guide, you will set up a Bun project with Prisma ORM and a Prisma Postgres database. You will create a simple HTTP server and build a Bun executable for deployment.

## Prerequisites

- [Bun](https://bun.sh/docs/installation) installed in your system
- A [Prisma Postgres database](/postgres) (created during setup)
- Basic knowledge of JavaScript/TypeScript

## 1. Setting up your Bun project

First, create a directory for your project and navigate to it:

```terminal
mkdir bun-prisma
cd bun-prisma
```

Then, initialise a new Bun project:

```terminal
bun init -y
```

This creates a basic Bun project that includes a `package.json` file and an `index.ts` file.

## 2. Installing and configuring Prisma

### 2.1. Install dependencies

Install the required Prisma packages and other dependencies:

```terminal
bun add -d prisma @types/pg
bun add @prisma/client @prisma/adapter-pg pg
```

:::info

If you are using a different database provider (MySQL, SQL Server, SQLite), install the corresponding driver adapter package instead of `@prisma/adapter-pg`. For more information, see [Database drivers](/orm/overview/databases/database-drivers).

:::

### 2.2. Initialize Prisma ORM with Prisma Postgres

Initialize Prisma ORM with Prisma Postgres in your project:

```terminal
bunx --bun prisma init --db
```

:::note

The `--bun` flag is required to ensure Prisma runs with the Bun runtime. Without it, Prisma falls back to Node.js due to the `#!/usr/bin/env node` shebang in the CLI.

:::

:::info

You'll need to answer a few questions while setting up your Prisma Postgres database. Select the region closest to your location and a memorable name for your database like "My Bun Project"

:::

This command creates:

- A `prisma/` directory with your `schema.prisma` file
- A new Prisma Postgres database
- A `prisma.config.ts` file
- A `.env` file with your `DATABASE_URL`

### 2.3. Configure environment variables for direct connection

We're going to use a direct connection string for connecting to Prisma Postgres. To get your [direct connection string](/postgres/database/direct-connections#how-to-connect-to-prisma-postgres-via-direct-tcp):

1. Navigate to your recently created Prisma Postgres project dashboard (e.g. "My Bun Project")
2. Click the **API Keys** tab in the project's sidebar
3. Click the **Create API key** button
4. Provide a name for the API key and click **Create**
5. Copy the connection string starting with `postgres://`

Update your `.env` file to replace the `DATABASE_URL` with the new connection string:

```env file=.env
//delete-start  
DATABASE_URL="your_database_url_here"
//delete-end
//add-start
DATABASE_URL="your_direct_connection_string_here"
//add-end
```

### 2.4. Update your Prisma schema

Open `prisma/schema.prisma` and update it to include your data model:

```prisma file=prisma/schema.prisma
generator client {
  provider = "prisma-client"
  output   = "../generated/prisma"
}

datasource db {
  provider = "postgresql"
}

//add-start  
model User {
  id    Int     @id @default(autoincrement())
  email String  @unique
  name  String?
}
//add-end
```

## 3. Generate Prisma Client and run migrations

Generate the Prisma client and apply your schema to the database:

```terminal
bunx --bun prisma migrate dev --name init
bunx --bun prisma generate
```

This command:

- Creates the database tables based on your schema
- Generates the Prisma client in the `generated/prisma` directory

## 4. Setting up database configuration and creating a seed script

### 4.1. Create a database utility file

Create a `db.ts` file in your project root to configure `PrismaClient`:

```typescript file=db.ts
import { PrismaClient } from "./generated/prisma/client";
import { PrismaPg } from "@prisma/adapter-pg";

const adapter = new PrismaPg({
  connectionString: process.env.DATABASE_URL!,
});

export const prisma = new PrismaClient({
  adapter,
});
```

### 4.2. Create a seed script

Create a seed script in the `prisma` folder to populate your database with sample data:

```typescript file=prisma/seed.ts
import { PrismaClient } from "../generated/prisma/client";
import { PrismaPg } from "@prisma/adapter-pg";

const adapter = new PrismaPg({
  connectionString: process.env.DATABASE_URL!,
});

const prisma = new PrismaClient({
  adapter,
});

async function main() {
  // Create multiple users
  await prisma.user.createMany({
    data: [
      { email: "alice@example.com", name: "Alice" },
      { email: "bob@example.com", name: "Bob" },
      { email: "charlie@example.com", name: "Charlie" },
      { email: "diana@example.com", name: "Diana" },
      { email: "eve@example.com", name: "Eve" },
      { email: "frank@example.com", name: "Frank" },
      { email: "grace@example.com", name: "Grace" },
      { email: "henry@example.com", name: "Henry" },
      { email: "isabella@example.com", name: "Isabella" },
      { email: "jack@example.com", name: "Jack" },
    ],
    skipDuplicates: true, // prevents errors if you run the seed multiple times
  });

  console.log("Seed data inserted!");
}

main()
  .catch((e) => {
    console.error(e);
    process.exit(1);
  })
  .finally(async () => {
    await prisma.$disconnect();
  });
```

### 3.3. Add the seed script to Prisma Config

Add the following content to the file:

```typescript file=prisma.config.ts
import { defineConfig, env } from 'prisma/config';

export default defineConfig({
  schema: 'prisma/schema.prisma',
  migrations: {
    path: 'prisma/migrations',
    // add-start
    seed: `bun run prisma/seed.ts`
    //add-end
  },
  datasource: {
    url: env('DATABASE_URL'),
  },
});
```

:::note

Unlike Node.js, Bun automatically loads `.env` files, so the `import 'dotenv/config'` line is not needed. If you see this import in your generated `prisma.config.ts`, you can safely remove it.

:::

Run the seed script to populate your database:

```terminal
bunx --bun prisma db seed
```

## 5. Creating your Bun server

Replace the `index.ts` file contents with the following code to build a simple HTTP server that uses Prisma ORM to fetch and display users:

```typescript file=index.ts
import { prisma } from './db'

const server = Bun.serve({
  port: 3000,
  async fetch(req) {
    const { pathname } = new URL(req.url)

    // Skip favicon route
    if (pathname === '/favicon.ico') {
      return new Response(null, { status: 204 }) // or serve an icon if you have one
    }

    // Return all users
    const users = await prisma.user.findMany()

    // Count all users
    const count = await prisma.user.count()

    // Format the response with JSON
    return new Response(
      JSON.stringify({
        users: users,
        totalUsers: count,
      }),
      { headers: { 'Content-Type': 'application/json' } },
    )
  },
})

console.log(`Listening on http://localhost:${server.port}`)
```

## 6. Running your application

Start your Bun server:

```terminal
bun run index.ts
```

You should see `Listening on http://localhost:3000` in the console. When you visit `http://localhost:3000` in your browser, you'll see a JSON response with all the users in your database and the total count.

## 7. Building and running a Bun executable

Bun can compile your [TypeScript application into a single executable file](https://bun.com/docs/bundler/executables), which is useful for deployment and distribution.

### 7.1. Build the executable

Build your application into an executable:

```terminal
bun build --compile index.ts
```

This creates an executable file named `index` (or `index.exe` on Windows) in your project directory.

### 7.2. Run the executable

Run the compiled executable:

```terminal
./index
```

You should see the same `Listening on http://localhost:3000` message, and your application will work exactly the same as before. The executable includes all dependencies and can be deployed to any compatible system without requiring Bun or Node.js to be installed.

:::note

Bun executables are useful for:

- **Deployment**: Ship a single file instead of managing dependencies
- **Distribution**: Share your application without requiring users to install Bun
- **Performance**: Faster startup times compared to running TypeScript files
- **Security**: Your source code is compiled and not easily readable

:::

## Next steps

You can explore [this example](https://pris.ly/bun_ppg_example) to see a sample application built with Bun and Prisma.

Now that you have a Bun application connected to a Prisma Postgres database, you can continue by:

- Extending your Prisma schema with additional models and relationships
- Implementing authentication and authorization
- Adding input validation and error handling
- Exploring Bun's built-in testing tools
- Deploying your executable to production servers

### More info

- [Bun Documentation](https://bun.sh/docs)
- [Prisma Config File](/orm/reference/prisma-config-reference)
- [Prisma Client without the Rust engine](/orm/prisma-client/setup-and-configuration/no-rust-engine)
- [Prisma Postgres](/postgres)

---

# Instant app deployment with Vercel and Prisma Postgres