Part 1: Set up the Project

Introduction

Now that you have the necessary background knowledge and your development environment set up, you can get your local project running!

There are many ways to author a Gatsby plugin or more generally speaking an npm package. Since we don’t want you to be stuck in decision fatigue on how to do things, you’ll learn how to build a Gatsby source plugin in TypeScript with just tsc (that is the TypeScript compiler). Later you can decide to use other tooling if you wish. The repository you’ll clone will also show how to test your plugin in a Gatsby site.

By the end of this part of the tutorial, you will have:

• Cloned the companion repository to your local machine
• Explored the project structure
• Installed all required dependencies and built all packages
• Spun up the local development server

Clone the repository

Clone the companion repository from GitHub to your desired location. The repository’s main branch shows the finished state after following this tutorial. You can reference its code as an additional resource while going through this guide.

After successfully cloning the repository, navigate to its folder and switch to the start branch to have a clean boilerplate:

Open the repository in your favorite editor as it’ll make the next step easier.

Project structure

The creating-source-plugin-tutorial project includes three directories:

• api: This is the example backend API
• plugin: The source plugin
• site: An example Gatsby site

The site uses the plugin which sources its data from api. As mentioned in Part 0 this project uses yarn workspaces to make this setup work.

By having the plugin and an example site that uses the plugin in the same repository, you can more easily test your plugin.

The plugin itself has a structure we’d also recommend following:

• A package.json file that sets gatsby and gatsby-plugin as its "keywords" so that Gatsby’s plugin search can pick it up
• A root gatsby-node.js that requires ./dist/gatsby-node (the compiled TypeScript file). At the moment Gatsby looks for a root gatsby-node.js file as its entry file.
• A well-written README that explains to the user in concise steps how to install, use, and configure your plugin (also see How to write a plugin README)
• A src folder with the plugin’s source code
  • A root gatsby-node.ts file that exports Gatsby Node APIs from individual files
  • Individual files that only contain the specific Node API (in kebab case), e.g. onPluginInit becomes on-plugin-init.ts. This will also make unit testing your plugin easier.

How you organize your src folder is of course up to you, but we’d recommend keeping things consistent and files lowercase.

Start the project

Ready to see something happen in your browser? Then let’s go!

First, install the necessary dependencies to run everything:

Afterwards, open a new window in your terminal (you should have two now).

In the first window, run the develop:deps script to start watching the api and plugin directories. If you change something inside api, the GraphQL server will be restarted, if you change something in plugin the TypeScript compiler will output updated files.

You should find something like this in your terminal:

Now, in your second terminal window, run the develop:site script. This runs gatsby develop for the example site:

While gatsby develop is running you should also note the info Example plugin loaded... log. This verifies that the plugin was successfully loaded for this initial demo. Yay 🎉

Once the development server is ready, go to http://localhost:8000, and be greeted by a minimalistic index page.

Key takeaways

• It’s good practice to develop your source plugin alongside an example site to be able to test it
• You can keep your code organized by placing each Gatsby Node API in its own file
• When making changes to your plugin, you’ll need to restart gatsby develop to see your changes applied

What’s coming next?

In Part 2 you’ll learn how to do the most important part of a Gatsby source plugin: sourcing data and displaying it on your site.