Deploy a Deno application

A Deno server runs on Sevalla as an application built from a Dockerfile: the official denoland/deno image provides the Deno version you pin, and the web process runs Deno.serve() on the port that Sevalla sets in the PORT environment variable. Sevalla’s default build strategy, Nixpacks, detects deno.json too, but Nixpacks 1.41 installs Deno 1.36, which can’t run Deno 2 projects. The Dockerfile in this guide pins Deno 2.9.7.

Before you begin

A Sevalla company with a payment method, and a GitHub, GitLab or Bitbucket account for the repository. See Git providers.
Deno 2 on your computer.

Create the project

Create a project with deno init:

deno init storefront
cd storefront

Replace main.ts with a server, and delete main_test.ts, which tests the starter’s example function:

main.ts

const port = Number(Deno.env.get("PORT") ?? 8000);

Deno.serve({ port, hostname: "0.0.0.0" }, () => {
  return new Response("Hello from Deno on Sevalla");
});

Add a start task to deno.json for running the server locally:

deno.json

{
  "tasks": {
    "start": "deno run --allow-net --allow-env main.ts"
  }
}

Keep the other fields that deno init wrote.

Prepare the project for Sevalla

The server already handles the port: it reads PORT, which Sevalla sets to the web process’s port (8080 by default), and listens on 0.0.0.0, all network interfaces. Reading PORT needs the --allow-env permission, and serving requests needs --allow-net. Create a Dockerfile in the repository root:

Dockerfile

FROM denoland/deno:2.9.7

WORKDIR /app

COPY . .
RUN deno cache main.ts

USER deno

CMD ["deno", "run", "--allow-net", "--allow-env", "main.ts"]

deno cache downloads and compiles the dependencies during the build, so instances don’t fetch them when they start.
USER deno runs the server as the image’s unprivileged user.
CMD is the web process’s start command. To run another command without changing the Dockerfile, set a Custom start command on the web process (see Processes).

Run deno task start and open http://localhost:8000 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.

Set the build strategy

Click the 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.

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 Deno 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 build log that mentions Nixpacks means the build strategy is still Nixpacks. If the server stops with a NotCapable error in the runtime logs, add the permission it names to the CMD line.

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 environment variables

Add configuration on the application’s Environment variables tab and read it with Deno.env.get(). A Dockerfile build receives variables marked Available during buildtime as build arguments, so the Dockerfile needs an ARG line for each one it uses during the build. Variables apply at the next deployment. See Environment variables.

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.

Migrate

JavaScript

Python

Deploy a Deno application

Before you begin

Create the project

Prepare the project for Sevalla

Deploy to Sevalla

Verify the deployment

Deploy changes

Use environment variables

Add a custom domain

​Before you begin

​Create the project

​Prepare the project for Sevalla

​Deploy to Sevalla

​Verify the deployment

​Deploy changes

​Use environment variables

​Add a custom domain

Before you begin

Create the project

Prepare the project for Sevalla

Deploy to Sevalla

Verify the deployment

Deploy changes

Use environment variables

Add a custom domain