**This does not change existing behavior.**
building to serverless is completely opt-in.
- Implements `target: 'serverless'` in `next.config.js`
- Removes `next build --lambdas` (was only available on next@canary so far)
This implements the concept of build targets. Currently there will be 2 build targets:
- server (This is the target that already existed / the default, no changes here)
- serverless (New target aimed at compiling pages to serverless handlers)
The serverless target will output a single file per `page` in the `pages` directory:
- `pages/index.js` => `.next/serverless/index.js`
- `pages/about.js` => `.next/serverless/about.js`
So what is inside `.next/serverless/about.js`? All the code needed to render that specific page. It has the Node.js `http.Server` request handler function signature:
```ts
(req: http.IncomingMessage, res: http.ServerResponse) => void
```
So how do you use it? Generally you **don't** want to use the below example, but for illustration purposes it's shown how the handler is called using a plain `http.Server`:
```js
const http = require('http')
// Note that `.default` is needed because the exported module is an esmodule
const handler = require('./.next/serverless/about.js').default
const server = new http.Server((req, res) => handler(req, res))
server.listen(3000, () => console.log('Listening on http://localhost:3000'))
```
Generally you'll upload this handler function to an external service like [Now v2](https://zeit.co/now-2), the `@now/next` builder will be updated to reflect these changes. This means that it'll be no longer neccesary for `@now/next` to do some of the guesswork in creating smaller handler functions. As Next.js will output the smallest possible serverless handler function automatically.
The function has 0 dependencies so no node_modules are required to run it, and is generally very small. 45Kb zipped is the baseline, but I'm sure we can make it even smaller in the future.
One important thing to note is that the function won't try to load `next.config.js`, so `publicRuntimeConfig` / `serverRuntimeConfig` are not supported. Reasons are outlined here: #5846
So to summarize:
- every page becomes a serverless function
- the serverless function has 0 dependencies (they're all inlined)
- "just" uses the `req` and `res` coming from Node.js
- opt-in using `target: 'serverless'` in `next.config.js`
- Does not load next.config.js when executing the function
TODO:
- [x] Compile next/dynamic / `import()` into the function file, so that no extra files have to be uploaded.
- [x] Setting `assetPrefix` at build time for serverless target
- [x] Support custom /_app
- [x] Support custom /_document
- [x] Support custom /_error
- [x] Add `next.config.js` property for `target`
Need discussion:
- [ ] Since the serverless target won't support `publicRuntimeConfig` / `serverRuntimeConfig` as they're runtime values. I think we should support build-time env var replacement with webpack.DefinePlugin or similar.
- [ ] Serving static files with the correct cache-control, as there is no static file serving in the serverless target
This brings us one step closer to outputting serverless functions as renderToHTML now renders the passed components, which allows us to bundle the renderToHTML function together with statically imported components in webpack.
Resolves#4055
Credit: https://github.com/zeit/next.js/pull/5095
I didn't use the ignore webpack plugin from the original PR and tested bundle size with https://github.com/zeit/next.js/pull/5339 - seems to be safe on that front.
Was able to get tests to pass locally, unsure of what goes wrong in CI 🤷♂️
**Questions**
1) The initial PR didn't include changes to `next-server/lib/router` in `getRouteInfo()`. Should the same changes be made within?
2) Should we add a test for rendering a component created via `forwardRef()`?
`component-with-forwardedRef`:
```javascript
export default React.forwardRef((props, ref) => <span {...props} forwardedRef={ref}>This is a component with a forwarded ref</span>);
```
some test:
```javascript
test('renders from forwardRef', async () => {
const $ = await get$('/component-with-forwardedRef')
const span = $('span')
expect(span.text()).toMatch(/This is a component with a forwarded ref/)
})
```
* Convert render.js to typescript
* Compile tsx files too
* Remove internal renderErrorToHTML function
* Interopt component result
* requirePage doesn’t need async
* Move out enhancing logic into it’s own function
* Remove buildManifest from renderPage
* Move render into it’s own function
* Change let to const
* Move renderDocument into it’s own function
