next.js/examples/custom-server-koa

Custom Koa Server example

How to use

Using create-next-app

Download create-next-app to bootstrap the example:

npx create-next-app --example custom-server-koa custom-server-koa-app
# or
yarn create next-app --example custom-server-koa custom-server-koa-app

Download manually

Download the example or clone the repo:

curl https://codeload.github.com/zeit/next.js/tar.gz/canary | tar -xz --strip=2 next.js-canary/examples/custom-server-koa
cd custom-server-koa

Install it and run:

npm install
npm run dev

Deploy it to the cloud with now (download)

now

The idea behind the example

Most of the times the default Next server will be enough but sometimes you want to run your own server to customize routes or other kind of the app behavior. Next provides a Custom server and routing so you can customize as much as you want.

Because the Next.js server is just a node.js module you can combine it with any other part of the node.js ecosystem. in this case we are using Koa to build a custom router on top of Next.

The example shows a server that serves the component living in pages/a.js when the route /b is requested and pages/b.js when the route /a is accessed. This is obviously a non-standard routing strategy. You can see how this custom routing is being made inside server.js.

Side note: Enabling gzip compression

The most common Koa middleware for handling the gzip compression is compress, but unfortunately it is currently not compatible with Next.
koa-compress handles the compression of the response body by checking res.body, which will be empty in the case of the routes handled by Next (because Next sends and ends the response by itself).

If you need to enable the gzip compression, the most simple way to do so is by wrapping the express-middleware compression with koa-connect:

const compression = require('compression');
const koaConnect = require('koa-connect');


server.use(koaConnect(compression()));