Quickstart

Table of contents

Follow this guide to get started with creating a basic Docker extension. The Quickstart guide automatically generates boilerplate files for you.

Prerequisites

Note

NodeJS and Go are only required when you follow the quickstart guide to create an extension. It uses the docker extension init command to automatically generate boilerplate files. This command uses a template based on a ReactJS and Go application.

In Docker Desktop settings, ensure you can install the extension you're developing. You may need to navigate to the Extensions tab in Docker Desktop settings and deselect Allow only extensions distributed through the Docker Marketplace.

Step one: Set up your directory

To set up your directory, use the init subcommand and provide a name for your extension.

$ docker extension init <my-extension>

The command asks a series of questions about your extension, such as its name, a description, and the name of your Hub repository. This helps the CLI generate a set of boilerplate files for you to get started. It stores the boilerplate files in the my-extension directory.

The automatically generated extension contains:

  • A Go backend service in the backend folder that listens on a socket. It has one endpoint /hello that returns a JSON payload.
  • A React frontend in the frontend folder that can call the backend and output the backend’s response.

For more information and guidelines on building the UI, see the Design and UI styling section.

Step two: Build the extension

To build the extension, move into the newly created directory and run:

$ docker build -t <name-of-your-extension> .

docker build builds the extension and generates an image named the same as the chosen hub repository. For example, if you typed john/my-extension as the answer to the following question:

? Hub repository (eg. namespace/repository on hub): john/my-extension`

The docker build generates an image with name john/my-extension.

Step three: Install and preview the extension

To install the extension in Docker Desktop, run:

$ docker extension install <name-of-your-extension>

To preview the extension in Docker Desktop, once the installation is complete and you should see a Quickstart item underneath the Extensions menu. Selecting this item opens the extension's frontend.

Tip

During UI development, it’s helpful to use hot reloading to test your changes without rebuilding your entire extension. See Preview whilst developing the UI for more information.

You may also want to inspect the containers that belong to the extension. By default, extension containers are hidden from the Docker Dashboard. You can change this in Settings, see how to show extension containers for more information.

Step four: Submit and publish your extension to the Marketplace

If you want to make your extension available to all Docker Desktop users, you can submit it for publication in the Marketplace. For more information, see Publish.

Clean up

To remove the extension, run:

$ docker extension rm <name-of-your-extension>

What's next