Splitting the code into small plugins

We implemented the API root endpoint in the Creating an API starter using Fastify recipe, which is often used as a health check to verify whether the server started successfully. However, we can’t keep adding all the application’s routes to the index.js file; otherwise, it would become unreadable in no time. So, let’s split our index.js file.

How to do it…

To split our index.js file, follow these steps:

1. Create an app.js file and move the serverOptions constant with the following server configuration:

   const serverOptions = {
     logger: true
   };

2. We define our first plugin interface:

   async function appPlugin (app, opts) {
     app.get('/', async function homeHandler () {
       return {
         api: 'fastify-restaurant-api',
         version: 1
       };
     });
   }

   A plugin is...