Deploying a Deno Express application to Fly

In this tutorial you will learn how to deploy a containerized Deno Express application to Fly.

The final code of this article can be found here.

#Prerequisites

• A Fly account
• A computer with Deno, Docker, and Flyctl (the Fly CLI)

#Creating the application

deps.ts

export { default as express } from "npm:express@4.18.2";

main.ts

import { express } from "./deps.ts";

const application = express();

const port = 8080;

application
  .get("/", (req, res) => {
    res.send({
      message: "Hello, World!",
    });
  })
  .get("/random", (req, res) => {
    res.send({
      number: Math.floor(Math.random() * 100),
    });
  });

application.listen(port, () => {
  console.log(`Application listening on port ${port}`);
});

To run the application locally:

deno run -A main.ts

#Containerizing the application

Dockerfile

FROM denoland/deno:alpine-1.30.0

WORKDIR /usr/src/app

COPY deps.ts .
RUN deno cache deps.ts

ADD . .
RUN deno cache main.ts

EXPOSE 8080

CMD ["run", "-A", "main.ts"]

To build and run the container locally:

docker build . -t hello-world
docker run -dp 8080:8080 hello-world

#Deploying the application

1. fly launch to prepare your fly.toml file, containing your project settings. Inside the fly.toml file, ensure the service's internal_port (8080 by default) matches the port exposed by your container.
2. fly deploy to deploy your application.
3. fly open to open the deployed application in your browser.

#Cleaning up

fly destroy your-unique-app-id -y removes your application from the Fly platform.

That's all! Don't forget to delete the application once you're done testing.

The final code of this article can be found here.