/**
   * Stops the server from accepting new connections and keeps existing
   * connections. This function is asynchronous, the server is finally closed
   * when all connections are ended and the server emits a `'close'` event.
   * The optional `callback` will be called once the `'close'` event occurs. Unlike
   * that event, it will be called with an `Error` as its only argument if the server
   * was not open when it was closed.
   * @since v0.1.90
   * @param callback Called when the server is closed.
   */
  close(callback?: (err?: Error) => void): this;

import Fastify from 'fastify';
const fastify = Fastify();

fastify.get('/', async (request, reply) => {
  await new Promise((resolve) => {
    setTimeout(() => resolve(1), 10000);
  });
  reply.send({ hello: 'world' });
});

setTimeout(() => {
  fastify.server.close((error) => {
    console.log('Server is closed', error);
  });
}, 5000);

// Run the server!
fastify.listen({ port: 3000 }, (err, address) => {
  if (err) throw err;
  // Server is now listening on ${address}
});