fix: allow next.config.js overwrite cache-control header

[u3u]

Update (2022-12-31): My Solution

Before the PR merge, if anyone else is bothered by it, my solution is to modify node_modules/next/dist/server/send-payload/revalidate-headers.js and then use patch-package to generate the patch. If you use pnpm then you can just use pnpm patch next to generate the patch using pnpm patch-commit after making changes in the temporary directory.

Fixes #21827, fixes #22319 #28557

https://nextjs.org/docs/api-reference/next.config.js/headers#cache-control

You cannot set Cache-Control headers in next.config.js file as these will be overwritten in production to ensure that API Routes and static assets are cached effectively.

In the documentation it is described that Cache-Control cannot be overridden and will affect static resources, but in fact static resources will set their own Cache-Control, so it does not seem to affect them.

next.js/packages/next/server/next-server.ts

Lines 428 to 451 in 9c41634

	match: getPathMatch('/_next/static/:path*'),
	type: 'route',
	name: '_next/static catchall',
	fn: async (req, res, params, parsedUrl) => {
	// make sure to 404 for /_next/static itself
	if (!params.path) {
	await this.render404(req, res, parsedUrl)
	return {
	finished: true,
	}
	}
	if (
	params.path[0] === CLIENT_STATIC_FILES_RUNTIME ||
	params.path[0] === 'chunks' ||
	params.path[0] === 'css' ||
	params.path[0] === 'image' ||
	params.path[0] === 'media' ||
	params.path[0] === this.buildId ||
	params.path[0] === 'pages' ||
	params.path[1] === 'pages'
	) {
	this.setImmutableAssetCacheControl(res)
	}

I use getHeader('Cache-Control') to check if the user has set their cache, which by default is the same behavior as before.
By the way hasHeader is undefined in some cases, I don't know why. (#34929 #37338)

[juulieen]

I would be interested in the merge of this PR too 👍

[bejarano-tech]

Fixes #21827, fixes #22319 #28557

https://nextjs.org/docs/api-reference/next.config.js/headers#cache-control

You cannot set Cache-Control headers in next.config.js file as these will be overwritten in production to ensure that API Routes and static assets are cached effectively.

In the documentation it is described that cache-control cannot be overridden and will affect static resources, but in fact static resources will set their own cache-control, so it does not seem to affect them.

next.js/packages/next/server/next-server.ts

Lines 428 to 451 in 9c41634

	match: getPathMatch('/_next/static/:path*'),
	type: 'route',
	name: '_next/static catchall',
	fn: async (req, res, params, parsedUrl) => {
	// make sure to 404 for /_next/static itself
	if (!params.path) {
	await this.render404(req, res, parsedUrl)
	return {
	finished: true,
	}
	}
	if (
	params.path[0] === CLIENT_STATIC_FILES_RUNTIME ||
	params.path[0] === 'chunks' ||
	params.path[0] === 'css' ||
	params.path[0] === 'image' ||
	params.path[0] === 'media' ||
	params.path[0] === this.buildId ||
	params.path[0] === 'pages' ||
	params.path[1] === 'pages'
	) {
	this.setImmutableAssetCacheControl(res)
	}

I use getHeader('Cache-Control') to check if the user has set their cache, which by default is the same behavior as before. By the way hasHeader is undefined in some cases, I don't know why. (#34929 #37338)

Hi, hasHeader is undefined when you have fallback: false in getStaticPaths

[meotimdihia]

@ijjk this feature is important for everyone who uses self-hosted + Cloudflare.

[benkingcode]

Any movement on this?

[cweekly]

Maintainers, please, could you review this change?

[mgray-bemyduo]

@timneutkens @stefanobrambilla @ijjk @shuding @huozhi @feedthejim
Can one of you please review this? It's been sitting here for almost a year and this bug is open because of it #22319
next-intl is not able to be used with server components until this is resolved. Please see here: https://next-intl-docs.vercel.app/docs/getting-started/app-router-server-components

[khalilsarwari]

This is a relatively small, opt-in change with huge usability benefits; both the issue and the solution are straightforward, can this please be prioritized?

@timneutkens @ijjk @huozhi

[a463]

This is still an issue. I would like to cache ISR pages locally, but not on the CDN. There seems to be no way to overwrite the Cache-Control header. Could this please be included with Next 15? It seems like a relatively simple change.

[kmrachko]

Adding one more voice to the crowd of people affected by that issue - please review it and either provide a clear explanation on why it's undesirable - or get it merged.

[ijjk]

Hi, went ahead and landed this against latest changes with added tests in #69802 thanks for looking into this!