next.js/test/integration/fetch-polyfill-ky-universal/api/api-route.js

import ky from 'ky-universal'

export default async function ApiRoute(_req, res) {
  const port = process.env.NEXT_PUBLIC_API_PORT
  const json = await ky.get(`http://localhost:${port}/`).json()
  res.json(json)
}