Deploy a Bun application

A Bun server runs on Sevalla as an application: Nixpacks sees bun.lock in your Git repository, installs Bun and the dependencies, and the web process runs bun run start. Bun.serve() reads the port that Sevalla sets in the PORT environment variable on its own.

Before you begin

A Sevalla company with a payment method, and a GitHub, GitLab or Bitbucket account for the repository. See Git providers.
Bun 1.3 or later on your computer.

Create the project

Create a project with bun init, which writes index.ts, package.json, bun.lock and a .gitignore:

mkdir storefront && cd storefront
bun init -y

Replace index.ts with a server:

index.ts

const server = Bun.serve({
  routes: {
    "/": new Response("Hello from Bun on Sevalla"),
  },
  fetch() {
    return new Response("Not Found", { status: 404 });
  },
});

console.log(`Listening on ${server.url}`);

Bun.serve() takes its port from BUN_PORT, PORT or NODE_PORT when you don’t pass one, and listens on 0.0.0.0 by default. Sevalla sets PORT to the web process’s port (8080 by default), so the server needs no port setting.

Prepare the project for Sevalla

Add a start script to package.json:

package.json

{
  "scripts": {
    "start": "bun run index.ts"
  }
}

Keep the other fields that bun init wrote. Commit bun.lock: Nixpacks, the default build strategy, detects Bun from bun.lock (or bun.lockb) or from a packageManager field that names Bun. It then installs Bun 1.3.0, runs bun i --no-save and starts the web process with bun run start. Without a lockfile or that field, Nixpacks treats the project as a Node.js project and bun isn’t installed. Bun runs TypeScript directly, so the project needs no build step. Run bun start and open http://localhost:3000 to check the server locally. Then commit everything and push it to your Git provider:

git init
git add .
git commit -m "Prepare for Sevalla"
git branch -M main
git remote add origin https://github.com/acme/storefront.git
git push -u origin main

Deploy to Sevalla

Create the application

In the sidebar, click Applications, then click Create > Application. Under Source, click Private repository, then choose the Git provider, the Repository and the Branch. Under Location, choose a Data center. Keep the Size at H1 or choose a larger one, then click Create application. The application opens on its Overview tab with the status Not deployed yet: creating an application doesn’t deploy it.

Deploy

Click the Overview tab, then click Deploy now under Recent deployments. Check the Branch and click Deploy.

Turn on auto-deploy

To deploy every push to the branch automatically, click the Settings tab, then click Update auto-deploy in the Auto-deploy section. Turn on Auto-deploy and click Update auto-deploy. See Deployments.

Verify the deployment

On the Deployments tab, wait for the deployment’s status to change to Deployed. The application’s status next to its name changes to Running.
Click the domain under the application’s name, for example storefront-x7k2m.sevalla.app. The page shows Hello from Bun on Sevalla.

The application header with its name, Running status, repository, branch and the domain that opens the application

If the deployment fails, open it on the Deployments tab and read its build log, then see Troubleshoot builds and deployments. A log that runs npm instead of bun means Nixpacks didn’t find bun.lock in the repository.

Deploy changes

With Auto-deploy on, every push to the branch starts a deployment; otherwise, click Deploy now for each change. Each deployment builds the image, then replaces the web process’s instances. See Deployments.

Use a newer Bun version

Nixpacks 1.41 always installs Bun 1.3.0. To run a newer release, build the application from a Dockerfile based on the official oven/bun image.

Add a Dockerfile

Create Dockerfile in the repository root, commit it and push it:

Dockerfile

FROM oven/bun:1.4
WORKDIR /app

COPY package.json bun.lock ./
RUN bun install --frozen-lockfile --production

COPY . .

USER bun
CMD ["bun", "run", "index.ts"]

Set the build strategy

Click the application’s Settings tab, then click Update build strategy. Choose Dockerfile, keep the Dockerfile path at Dockerfile and the Docker context at ., and click Update build strategy.

Deploy

Click the Overview tab, then click Deploy now under Recent deployments. Check the Branch and click Deploy.

See Dockerfile for the other Dockerfile settings.

Add a custom domain

To serve the application from your own domain, such as shop.example.com, add the domain on the application’s Domains tab and create the DNS records that Sevalla shows. Custom domains need a web process larger than H1, so scale the web process first. See Custom domains.

Connect a database

Create a database in the same location as the application, then connect the application to it with Add environment variables to the application turned on. Sevalla adds DB_URL, DB_HOST, DB_PORT, DB_DATABASE, DB_USERNAME and DB_PASSWORD to the application (what each one holds), and they apply at the next deployment. Bun’s built-in SQL client reads a PostgreSQL URL: import { SQL } from "bun", then new SQL(process.env.DB_URL).

Migrate

JavaScript

Python

Deploy a Bun application

Before you begin

Create the project

Prepare the project for Sevalla

Deploy to Sevalla

Verify the deployment

Deploy changes

Use a newer Bun version

Add a custom domain

Connect a database

​Before you begin

​Create the project

​Prepare the project for Sevalla

​Deploy to Sevalla

​Verify the deployment

​Deploy changes

​Use a newer Bun version

​Add a custom domain

​Connect a database

Before you begin

Create the project

Prepare the project for Sevalla

Deploy to Sevalla

Verify the deployment

Deploy changes

Use a newer Bun version

Add a custom domain

Connect a database