> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sevalla.com/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> These are the docs for Sevalla, a platform for deploying applications, databases, static sites, object storage and load balancers. The dashboard is at https://app.sevalla.com.
> Bold text in steps is an exact dashboard label.
> To act on a Sevalla account, prefer the Sevalla MCP server (https://mcp.sevalla.com/mcp, see https://docs.sevalla.com/ai-agents/overview.md), then the Sevalla CLI (https://docs.sevalla.com/developer-tools/cli.md), then the REST API (https://api-docs.sevalla.com, OpenAPI spec at https://api.sevalla.com/v3/openapi.json).
> Every page index is at https://docs.sevalla.com/llms.txt.

# Deploy Fastify

> Deploy a Fastify 5 server to Sevalla from a Git repository: listen on 0.0.0.0 and the PORT variable, set the start script, pin Node.js 24 and deploy it.

A Fastify server runs on Sevalla as an application: Nixpacks installs the dependencies from your Git repository, and the web process runs `npm start`, which starts Fastify on the port that Sevalla sets in the `PORT` environment variable.

## Before you begin

* A Sevalla company with a payment method, and a GitHub, GitLab or Bitbucket account for the repository. See [Git providers](/git/overview).
* Node.js 24 or later on your computer.

## Create the project

Create a folder and install Fastify:

```bash theme={null}
mkdir storefront && cd storefront
npm init -y
npm install fastify
```

Create the server:

```js server.js theme={null}
import Fastify from "fastify";

const fastify = Fastify({ logger: true });

fastify.get("/", async () => {
  return { message: "Hello from Fastify on Sevalla" };
});

await fastify.listen({
  port: Number(process.env.PORT) || 3000,
  host: "0.0.0.0",
});
```

Keep installed packages out of the repository:

```text .gitignore theme={null}
node_modules/
```

## Prepare the project for Sevalla

Set the module type, the start script and the Node.js version in `package.json`:

```bash theme={null}
npm pkg set type=module scripts.start="node server.js" engines.node="24.x"
```

| Field | Why Sevalla needs it |
| - | - |
| `"type": "module"` | Lets `server.js` use `import` and top-level `await`. |
| `scripts.start` | Nixpacks, the default [build strategy](/applications/builds/nixpacks), starts the web process with `npm run start`. |
| `engines.node` | Nixpacks installs Node.js 24 instead of its default, Node.js 18. See [Pin the Node.js version](/guides/javascript/overview#pin-the-node-js-version). |

The `listen()` call matters most:

* `port` comes from [`PORT`](/guides/javascript/overview#listen-on-the-port-environment-variable), which Sevalla sets to the web process's port (`8080` by default).
* `host: "0.0.0.0"` makes Fastify accept connections on all network interfaces. Fastify listens only on `localhost` by default, where Sevalla's traffic can't reach it.

Run `npm start` and open `http://localhost:3000` to check the server locally. Then commit everything and push it to your Git provider:

```bash theme={null}
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

<Steps>
  <Step title="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.
  </Step>

  <Step title="Deploy">
    Click the **Overview** tab, then click **Deploy now** under **Recent deployments**. Check the **Branch** and click **Deploy**.
  </Step>

  <Step title="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](/applications/deployments#deploy-automatically-on-push).
  </Step>
</Steps>

## Verify the deployment

1. 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**.
2. Click the domain under the application's name, for example `storefront-x7k2m.sevalla.app`. The page shows `{"message":"Hello from Fastify on Sevalla"}`.

<Frame>
  <img className="block dark:hidden" src="https://assets.sevalla.com/screenshots/light/app-overview-address.png" alt="The application header with its name, Running status, repository, branch and the domain that opens the application" width="1192" />

  <img className="hidden dark:block" src="https://assets.sevalla.com/screenshots/dark/app-overview-address.png" alt="The application header with its name, Running status, repository, branch and the domain that opens the application" width="1192" />
</Frame>

If the deployment fails, open it on the **Deployments** tab and read its build log, then see [Troubleshoot builds and deployments](/applications/troubleshooting/builds-and-deployments). If it deploys but the domain doesn't respond, check that `listen()` uses `host: "0.0.0.0"` and read the application's [runtime logs](/applications/logs): Fastify's logger prints the address it listens on.

## 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](/applications/deployments).

## 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](/applications/scaling) the web process first. See [Custom domains](/domains/overview).

## Connect a database

Create a [database](/databases/create) in the same location as the application, then [connect the application to it](/databases/connect#connect-an-application) 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](/databases/connect#environment-variables-an-internal-connection-adds)), and they apply at the next deployment. Read them in the server with `process.env.DB_URL`.


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