### 📖 What's in there?
Dynamic code evaluation (`eval()`, `new Function()`, ...) is not
supported on the edge runtime, hence why we fail the build when
detecting such statement in the middleware or `experimental-edge` routes
at build time.
However, there could be false positives, which static analysis and
tree-shaking can not exclude:
- `qs` through these dependencies (get-intrinsic:
[source](https://github.com/ljharb/get-intrinsic/blob/main/index.js#L12))
- `function-bind`
([source](https://github.com/Raynos/function-bind/blob/master/implementation.js#L42))
- `has`
([source](https://github.com/tarruda/has/blob/master/src/index.js#L5))
This PR leverages the existing `config` export to let user allow some of
their files.
it’s meant for allowing users to import 3rd party modules who embed
dynamic code evaluation, but do not use it (because or code paths), and
can't be tree-shaked.
By default, it’s keeping the existing behavior: warn in dev, fails to
build.
If users allow dynamic code, and that code is reached at runtime, their
app stills breaks.
### 🧪 How to test?
- (existing) integration tests for disallowing dynamic code evaluation:
`pnpm testheadless --testPathPattern=runtime-dynamic`
- (new) integration tests for allowing dynamic code evaluation: `pnpm
testheadless --testPathPattern=runtime-configurable`
- (amended) production tests for validating the new configuration keys:
`pnpm testheadless --testPathPattern=config-validations`
To try it live, you could have an application such as:
```js
// lib/index.js
/* eslint-disable no-eval */
export function hasUnusedDynamic() {
if ((() => false)()) {
eval('100')
}
}
export function hasDynamic() {
eval('100')
}
// pages/index.jsx
export default function Page({ edgeRoute }) {
return <p>{edgeRoute}</p>
}
export const getServerSideProps = async (req) => {
const res = await fetch(`http://localhost:3000/api/route`)
const data = await res.json()
return { props: { edgeRoute: data.ok ? `Hi from the edge route` : '' } }
}
// pages/api/route.js
import { hasDynamic } from '../../lib'
export default async function handle() {
hasDynamic()
return Response.json({ ok: true })
}
export const config = {
runtime: 'experimental-edge' ,
allowDynamic: '/lib/**'
}
```
Playing with `config.allowDynamic`, you should be able to:
- build the app even if it uses `eval()` (it will obviously fail at
runtime)
- build the app that _imports but does not use_ `eval()`
- run the app in dev, even if it uses `eval()` with no warning
### 🆙 Notes to reviewers
Before adding documentation and telemetry, I'd like to collect comments
on a couple of points:
- the overall design for this feature: is a list of globs useful and
easy enough?
- should the globs be relative to the application root (current
implementation) to to the edge route/middleware file?
- (especially to @sokra) is the implementation idiomatic enough? I've
leverage loaders to read the _entry point_ configuration once, then the
ModuleGraph to get it back during the parsing phase. I couldn't re-use
the existing `getExtractMetadata()` facility since it's happening late
after the parsing.
- there's a glitch with `import { ServerRuntime } from '../../types'` in
`get-page-static-info.ts`
([here](https://github.com/vercel/next.js/pull/39539/files#diff-cb7ac6392c3dd707c5edab159c3144ec114eafea92dad5d98f4eedfc612174d2L12)).
I had to use `next/types` because it was failing during lint. Any clue
why?
### ☑️ Checklist
- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [x] Integration tests added
- [x] Documentation added
- [x] Telemetry added. In case of a feature if it's used or not.
- [x] Errors have helpful link attached, see `contributing.md`
## Feature
As the title, support `has` match, `local` that works the same with the `rewrites` and `redirects` of next.config.js on middleware config. With this PR, you can write the config like the following:
```js
export const config = {
matcher: [
"/foo",
{ source: "/bar" },
{
source: "/baz",
has: [
{
type: 'header',
key: 'x-my-header',
value: 'my-value',
}
]
},
{
source: "/en/asdf",
locale: false,
},
]
}
```
Also, fixes https://github.com/vercel/next.js/issues/39428
related https://github.com/vercel/edge-functions/issues/178, https://github.com/vercel/edge-functions/issues/179
- [x] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
Co-authored-by: JJ Kasper <jj@jjsweb.site>
## How to reproduce
1. create a next.js app with a middleware (or an edge route) that imports a node.js module:
```js
// middleware.js
import { NextResponse } from 'next/server'
import { basename } from 'path'
export default async function middleware() {
basename()
return NextResponse.next()
}
```
2. deploy it to vercel with `vc`
3. go to the your function logs in Vercel Front (https://vercel.com/$user/$project/$deployment/functions)
4. in another tab, query your application
> it results in a 500 page:
<img width="517" alt="image" src="https://user-images.githubusercontent.com/186268/179557102-72568ca9-bcfd-49e2-9b9c-c51c3064f2d7.png">
> in the logs you should see:
<img width="1220" alt="image" src="https://user-images.githubusercontent.com/186268/179557266-498f3290-b7df-46ac-8816-7bb396821245.png">
## Expected behavior
The route should fail indeed in a 500, because Edge runtime **does not support node.js modules**. However the error in logs should be completely different:
```shell
error - Error: The edge runtime does not support Node.js 'path' module.
Learn More: https://nextjs.org/docs/messages/node-module-in-edge-runtime
```
## Notes to reviewers
I introduced this issue in #38234.
Prior to the PR above, the app would not even build, as we were checking imported node.js module during the build with AST analysis.
Since #38234, the app would build and should fail at runtime, with an appropriate error.
The mistake was to declare `__import_unsupported` function in the sandbox's context, that is only used in `next dev` and `next start`, but not shipped to Vercel platform.
By loading it inside webpack loaders (both middleware and edge route), we ensure it will be defined on Vercel as well.
The existing test suite (`pnpm testheadless --testPathPattern=runtime-module-error`) covers them.
## Bug
fixes#37106
Please note that, as for `pages/` the `src/middleware` file is ignored when `/middleware` is present.
## How to test
1. Rebuild next.js `pnpm build`
2. Run dedicated tests: `pnpm testheadless --testPathPattern middleware-src/`
This PR will allow Middleware to set its matcher through `export const config = { matching: ... }`
## Related
* This PR is rebased off #37121
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes by running `yarn lint`
_Hello Next.js team! First PR here, I hope I've followed the right practices._
### What's in there?
It has been decided to only support the following uses cases in Next.js' middleware:
- rewrite the URL (`x-middleware-rewrite` response header)
- redirect to another URL (`Location` response header)
- pass on to the next piece in the request pipeline (`x-middleware-next` response header)
1. during development, a warning on console tells developers when they are returning a response (either with `Response` or `NextResponse`).
2. at build time, this warning becomes an error.
3. at run time, returning a response body will trigger a 500 HTTP error with a JSON payload containing the detailed error.
All returned/thrown errors contain a link to the documentation.
This is a breaking feature compared to the _beta_ middleware implementation, and also removes `NextResponse.json()` which makes no sense any more.
### How to try it?
- runtime behavior: `HEADLESS=true yarn jest test/integration/middleware/core`
- build behavior : `yarn jest test/integration/middleware/build-errors`
- development behavior: `HEADLESS=true yarn jest test/development/middleware-warnings`
### Notes to reviewers
The limitation happens in next's web adapter. ~The initial implementation was to check `response.body` existence, but it turns out [`Response.redirect()`](https://github.com/vercel/next.js/blob/canary/packages/next/server/web/spec-compliant/response.ts#L42-L53) may set the response body (https://github.com/vercel/next.js/pull/31886). Hence why the proposed implementation specifically looks at response headers.~
`Response.redirect()` and `NextResponse.redirect()` do not need to include the final location in their body: it is handled by next server https://github.com/vercel/next.js/blob/canary/packages/next/server/next-server.ts#L1142
Because this is a breaking change, I had to adjust several tests cases, previously returning JSON/stream/text bodies. When relevant, these middlewares are returning data using response headers.
About DevEx: relying on AST analysis to detect forbidden use cases is not as good as running the code.
Such cases are easy to detect:
```js
new Response('a text value')
new Response(JSON.stringify({ /* whatever */ })
```
But these are false-positive cases:
```js
function returnNull() { return null }
new Response(returnNull())
function doesNothing() {}
new Response(doesNothing())
```
However, I see no good reasons to let users ship middleware such as the one above, hence why the build will fail, even if _technically speaking_, they are not setting the response body.
## Feature
- [x] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [x] Integration tests added
- [x] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [x] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [x] Make sure the linting passes by running `yarn lint`
This PR deprecates declaring a middleware under `pages` in favour of the project root naming it after `middleware` instead of `_middleware`. This is in the context of having a simpler execution model for middleware and also ships some refactor work. There is a ton of a code to be simplified after this deprecation but I think it is best to do it progressively.
With this PR, when in development, we will **fail** whenever we find a nested middleware but we do **not** include it in the compiler so if the project is using it, it will no longer work. For production we will **fail** too so it will not be possible to build and deploy a deprecated middleware. The error points to a page that should also be reviewed as part of **documentation**.
Aside from the deprecation, this migrates all middleware tests to work with a single middleware. It also splits tests into multiple folders to make them easier to isolate and work with. Finally it ships some small code refactor and simplifications.
This PR brings some significant refactoring in preparation for upcoming middleware changes. Each commit can be reviewed independently, here is a summary of what each one does and the reasoning behind it:
- [Move pagesDir to next-dev-server](f2fe154c00) simply moves the `pagesDir` property to the dev server which is the only place where it is needed. Having it for every server is misleading.
- [Move (de)normalize page path utils to a file page-path-utils.ts](27cedf0871) Moves the functions to normalize and denormalize page paths to a single file that is intended to hold every utility function that transforms page paths. Since those are complementary it makes sense to have them together. I also added explanatory comments on why they are not idempotent and examples for input -> output that I find very useful.
- [Extract removePagePathTail](6b121332aa) This extracts a function to remove the tail on a page path (absolute or relative). I'm sure there will be other contexts where we can use it.
- [Extract getPagePaths and refactor findPageFile](cf2c7b842e) This extracts a function `getPagePaths` that is used to generate an array of paths to inspect when looking for a page file from `findPageFile`. Then it refactors such function to use it parallelizing lookups. This will allow us to print every path we look at when looking for a file which can be useful for debugging. It also adds a `flatten` helper.
- [Refactor onDemandEntryHandler](4be685c37e) I've found this one quite difficult to understand so it is refactored to use some of the previously mentioned functions and make it easier to read.
- [Extract absolutePagePath util](3bc0783474) Extracts yet another util from the `next-dev-server` that transforms an absolute path into a page name. Of course it adds comments, parameters and examples.
- [Refactor MiddlewarePlugin](c595a2cc62) This is the most significant change. The logic here was very hard to understand so it is totally redistributed with comments. This also removes a global variable `ssrEntries` that was deprecated in favour of module metadata added to Webpack from loaders keeping less dependencies. It also adds types and makes a clear distinction between phases where we statically analyze the code, find metadata and generate the manifest file cc @shuding @huozhi
EDIT:
- [Split page path utils](158fb002d0) After seeing one of the utils was being used by the client while it was defined originally in the server, with this PR we are splitting the util into multiple files and moving it to `shared/lib` in order to make explicit that those can be also imported from client.
Fixes the problem that global `process` variable has only the `env` field.
Also fixed the issue that the `env` field is empty when the `process` module is used as the value of the variable (which happens when the module is contained in a dependency of application).
## Bug
- [ ] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
This PR adds support for [Middleware as per RFC ](https://github.com/vercel/next.js/discussions/29750).
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes
