fix setAssetPrefix when running on NextCustomServer

[alyahmedaly]

What?

Fixes setAssetPrefix when running on a custom server using next() function

Why?

Looks like when we run next custom server, there are 2 instances created to handle this case

• main server in /server/next.ts
• and Render server ./server/lib/render-server.ts

The issue mainly happens when calling setAssetPrefix it will update only the main server and not render server

  const next = require('next')
  const app = next({ });
    app.setAssetPrefix('my-fancy-cdn/static');
    app.render(); // render server is used instead of the main server

How?

when calling setAssetPrefix on the main server also update the render server with the same information.

Fixes: #59940
Fixes: #51223
Fixes: #61383

Related Resources

#53523 #49805

https://github.com/vercel/next.js/blob/c9c6ff6d77d3f7b61b955452bd31ec84c5e71cf0/docs/03-pages/01-building-your-application/06-configuring/10-custom-server.mdx

[ijjk]

Stats from current PR

Default Build

General Overall increase ⚠️

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
buildDuration	11.9s	12s	N/A
buildDurationCached	6.2s	5.6s	N/A
nodeModulesSize	200 MB	200 MB	⚠️ +1.67 kB
nextStartRea..uration (ms)	405ms	408ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
3f784ff6-HASH.js gzip	53.4 kB	53.4 kB	✓
423.HASH.js gzip	185 B	181 B	N/A
68-HASH.js gzip	29.8 kB	29.8 kB	N/A
framework-HASH.js gzip	45.2 kB	45.2 kB	✓
main-app-HASH.js gzip	238 B	240 B	N/A
main-HASH.js gzip	31.8 kB	31.8 kB	N/A
webpack-HASH.js gzip	1.7 kB	1.7 kB	✓
Overall change	100 kB	100 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
_app-HASH.js gzip	194 B	195 B	N/A
_error-HASH.js gzip	182 B	181 B	N/A
amp-HASH.js gzip	502 B	501 B	N/A
css-HASH.js gzip	320 B	322 B	N/A
dynamic-HASH.js gzip	2.5 kB	2.5 kB	N/A
edge-ssr-HASH.js gzip	255 B	256 B	N/A
head-HASH.js gzip	350 B	349 B	N/A
hooks-HASH.js gzip	368 B	369 B	N/A
image-HASH.js gzip	4.19 kB	4.18 kB	N/A
index-HASH.js gzip	257 B	256 B	N/A
link-HASH.js gzip	2.61 kB	2.61 kB	N/A
routerDirect..HASH.js gzip	310 B	311 B	N/A
script-HASH.js gzip	384 B	383 B	N/A
withRouter-HASH.js gzip	306 B	308 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	106 B	106 B	✓

Client Build Manifests

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
_buildManifest.js gzip	483 B	484 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
index.html gzip	528 B	528 B	✓
link.html gzip	539 B	538 B	N/A
withRouter.html gzip	523 B	523 B	✓
Overall change	1.05 kB	1.05 kB	✓

Edge SSR bundle Size

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
edge-ssr.js gzip	94 kB	94.1 kB	N/A
page.js gzip	150 kB	150 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
middleware-b..fest.js gzip	622 B	624 B	N/A
middleware-r..fest.js gzip	151 B	149 B	N/A
middleware.js gzip	37.7 kB	37.7 kB	N/A
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	1.92 kB	1.92 kB	✓

Next Runtimes

	vercel/next.js canary	alyahmedaly/next.js fix/setAssetPrefix-with-nextCustomServer	Change
app-page-exp...dev.js gzip	170 kB	170 kB	✓
app-page-exp..prod.js gzip	95.8 kB	95.8 kB	✓
app-page-tur..prod.js gzip	96.4 kB	96.4 kB	✓
app-page-tur..prod.js gzip	91 kB	91 kB	✓
app-page.run...dev.js gzip	142 kB	142 kB	✓
app-page.run..prod.js gzip	90.3 kB	90.3 kB	✓
app-route-ex...dev.js gzip	22.2 kB	22.2 kB	✓
app-route-ex..prod.js gzip	14.9 kB	14.9 kB	✓
app-route-tu..prod.js gzip	14.9 kB	14.9 kB	✓
app-route-tu..prod.js gzip	14.5 kB	14.5 kB	✓
app-route.ru...dev.js gzip	21.7 kB	21.7 kB	✓
app-route.ru..prod.js gzip	14.5 kB	14.5 kB	✓
pages-api-tu..prod.js gzip	9.43 kB	9.43 kB	✓
pages-api.ru...dev.js gzip	9.7 kB	9.7 kB	✓
pages-api.ru..prod.js gzip	9.43 kB	9.43 kB	✓
pages-turbo...prod.js gzip	22 kB	22 kB	✓
pages.runtim...dev.js gzip	22.7 kB	22.7 kB	✓
pages.runtim..prod.js gzip	22 kB	22 kB	✓
server.runti..prod.js gzip	49.7 kB	49.7 kB	✓
Overall change	933 kB	933 kB	✓

Commit: df312d4

[ijjk]

Thanks for the PR! Went ahead and enabled our custom-server test suite again which ensures we don't regress on this.

[gaojude]

Nice - and fwiw, I think it allows us to tap into the internals of the Next server by accessing app["renderServer"]!

[shaunwarman]

Still seeing next.config.js assetPrefix value coming in for some of the chunks.

#59940 (comment)

[ijjk]

@gaojude just a heads up any internals accessed are not covered by semver only public APIs.

[gaojude]

Still seeing next.config.js assetPrefix value coming in for some of the chunks.

#59940 (comment)

is it due to the use of

next.js/packages/next/src/server/response-cache/index.ts

Line 17 in 375d85d

export default class ResponseCache implements ResponseCacheBase {

? i have the same issue. most of the links still have the initial asset prefix..

[ijjk]

See here #59940 (comment) for a deeper explanation why changing the assetPrefix during build and runtime can cause issues