Containerize a Bun application

Table of contents

Prerequisites

You have a Git client. The examples in this section use a command-line based Git client, but you can use any client.

For a long time, Node.js has been the de-facto runtime for server-side JavaScript applications. Recent years have seen a rise in new alternative runtimes in the ecosystem, including Bun website. Like Node.js, Bun is a JavaScript runtime. Bun is a comparatively lightweight runtime that is designed to be fast and efficient.

Why develop Bun applications with Docker? Having multiple runtimes to choose from is great. But as the number of runtimes increases, it becomes challenging to manage the different runtimes and their dependencies consistently across environments. This is where Docker comes in. Creating and destroying containers on demand is a great way to manage the different runtimes and their dependencies. Also, as it's fairly a new runtime, getting a consistent development environment for Bun can be challenging. Docker can help you set up a consistent development environment for Bun.

Get the sample application

Clone the sample application to use with this guide. Open a terminal, change directory to a directory that you want to work in, and run the following command to clone the repository:

$ git clone https://github.com/dockersamples/bun-docker.git && cd bun-docker

You should now have the following contents in your bun-docker directory.

├── bun-docker/
│ ├── compose.yml
│ ├── Dockerfile
│ ├── LICENSE
│ ├── server.js
│ └── README.md

Create a Dockerfile

Before creating a Dockerfile, you need to choose a base image. You can either use the Bun Docker Official Image or a Docker Hardened Image (DHI) from the Hardened Image catalog.

Choosing DHI offers the advantage of a production-ready image that is lightweight and secure. For more information, see Docker Hardened Images.

Docker Hardened Images (DHIs) are available for Bun on Docker Hub. Unlike using the Docker Official Image, you must first mirror the Bun image into your organization and then use it as your base image. Follow the instructions in the DHI quickstart to create a mirrored repository for Bun.

Mirrored repositories must start with dhi-, for example: FROM <your-namespace>/dhi-bun:<tag>. In the following Dockerfile, the FROM instruction uses <your-namespace>/dhi-bun:1 as the base image.

# Use the DHI Bun image as the base image
FROM <your-namespace>/dhi-bun:1

# Set the working directory in the container
WORKDIR /app

# Copy the current directory contents into the container at /app
COPY . .

# Expose the port on which the API will listen
EXPOSE 3000

# Run the server when the container launches
CMD ["bun", "server.js"]

Using the Docker Official Image is straightforward. In the following Dockerfile, you'll notice that the FROM instruction uses oven/bun as the base image.

You can find the image on Docker Hub. This is the Docker Official Image for Bun created by Oven, the company behind Bun, and it's available on Docker Hub.

# Use the official Bun image
FROM oven/bun:latest

# Set the working directory in the container
WORKDIR /app

# Copy the current directory contents into the container at /app
COPY . .

# Expose the port on which the API will listen
EXPOSE 3000

# Run the server when the container launches
CMD ["bun", "server.js"]

In addition to specifying the base image, the Dockerfile also:

Sets the working directory in the container to /app.
Copies the content of the current directory to the /app directory in the container.
Exposes port 3000, where the API is listening for requests.
And finally, starts the server when the container launches with the command bun server.js.

Run the application

Inside the bun-docker directory, run the following command in a terminal.

$ docker compose up --build

Open a browser and view the application at http://localhost:3000. You will see a message {"Status" : "OK"} in the browser.

In the terminal, press ctrl+c to stop the application.

Run the application in the background

You can run the application detached from the terminal by adding the -d option. Inside the bun-docker directory, run the following command in a terminal.

$ docker compose up --build -d

Open a browser and view the application at http://localhost:3000.

In the terminal, run the following command to stop the application.

$ docker compose down

Summary

In this section, you learned how you can containerize and run your Bun application using Docker.

Related information:

Next steps

In the next section, you'll learn how you can develop your application using containers.