Nextjs 15.1 not saving Static Content on Redis on build time using instrumentation.

[joanaavelar]

Brief Description of the Bug
I was expecting to use instrumentation implementation and have Redis cache being populated with pre-rendered pages on build time, but it's only happening on start time. Besides that, I am unable to save the pre-rendered page if my page is on the root of the app, meaning app/page.tsx.

Severity
[Critical]

Frequency of Occurrence
[Always]

Steps to Reproduce

• Update url from cache-handler with your Redis instance
• yarn install
• yarn build
• Verify that no key exists for /index in Redis
• yarn start
• Verify that no key exists for /index in Redis, but /xpto in Redis exists
• Go to the browser and open => http://localhost:3000/
• Verify that /index key exists in Redis

Expected vs. Actual Behavior
I was expecting to have /index and /xpto after yarn build. I don't have anything being saved.
I was expecting to have /index also after yarn start. I only have /xpto being saved.

Screenshots/Logs
After yarn start

After accessing http://localhost:3000/

Environment:

• @neshca/cache-handler version: [e.g., 1.9.9]
• next version: [e.g., 15.1 and also 14.2.17]

Dependencies and Versions
I have a sample attached.

Attempted Solutions or Workarounds
No workarounds.

Impact of the Bug
I am unable to save my pre-rendered page on Redis if it's on app/page.tsx and it's only after yarn start and not after yarn build

Additional context
cache-test.zip

Sample attached.

[AyronK]

https://github.com/caching-tools/next-shared-cache/blob/canary/packages/cache-handler/src/instrumentation/register-initial-cache.ts

Instrumentation hook uses kind: 'PAGE', and kind: 'ROUTE', and Next 15 uses kind: APP_PAGE and kind: 'APP_ROUTE',

This is what causes instrumentation to fail initializing proper data and conflicts with what Next expects to get.

[miguelsoldado-altice]

I noticed something when running the example config with NEXT_PRIVATE_DEBUG_CACHE on.

When starting up the server besides the other regular CacheHandler logs I get a warning with:
[CacheHandler] [registerInitialCache] Failed to read page html file Error: Error: ENOENT: no such file or directory, stat '...\.next\standalone\.next\server\app\.html'

It seems that instrumentation is getting the cache data from the server and is trying to access ...\.next\standalone\.next\server\app\.html instead of ...\.next\standalone\.next\server\app\index.html which would be the correct path for the root page html. When I manually change the index.html file to just .html file (as well as index.rsc and index.meta) the runtime cache for the root path is correctly populated in redis.

I also assumed that no cache data would be stored in the server itself but it doesn't seem to be the case even when setting cacheMaxMemorySize: 0. Is there any way of storing the html cache data at build time in redis?

[miguelsoldado-altice]

I tracked down the issue a bit more into the register-initial-cache.ts file in this lib. it seems that we are passing the key from the routes in the prerenderManifest to a setPageCache function here:

    for (const [cachePath, { dataRoute, initialRevalidateSeconds }] of Object.entries(prerenderManifest.routes)) {
        if (populatePages && dataRoute?.endsWith('.json')) {
            await setPageCache(cachePath, 'pages', initialRevalidateSeconds);
        } else if (populatePages && dataRoute?.endsWith('.rsc')) {
            await setPageCache(cachePath, 'app', initialRevalidateSeconds);
        } else if (populateRoutes && dataRoute === null) {
            await setRouteCache(cachePath, 'app', initialRevalidateSeconds);
        }
    }

and setPageCache later uses this cachePath to try and get the .html, .rsc (if in the app router) and .meta files from the .next folder.
The key in the prerenderManifest is not index but "/" so the cache handler tries to use the path .next\server\app\.html

Prerender manifest route for "/":

    "/": {
      "experimentalBypassFor": [
        {
          "type": "header",
          "key": "Next-Action"
        },
        {
          "type": "header",
          "key": "content-type",
          "value": "multipart/form-data;.*"
        }
      ],
      "initialRevalidateSeconds": 3600,
      "srcRoute": "/[[...slug]]",
      "dataRoute": "/index.rsc"
    }

Maybe the dataRoute should be used here instead of the object key?

[ericnation]

Just bumping this and checking when v2.0 will be launched for compatibility with NextJS v15+? 🙏

[AyronK]

#846 @ericnation we've also made a workaround that works in Next 15 - #846 (comment)_

[PPuslecki]

#846 @ericnation we've also made a workaround that works in Next 15 - #846 (comment)_

When is 2.0 planned to be released?