Better debugging

[haapti]

Next.js extends the Web fetch() API to allow each request on the server to set its own persistent caching and revalidation semantics.

In production or for production build it is hard to debug and see how many requests are server from Redis cache or any cache if you are not running your app in Vercel. Only in dev mode Next.js exports logs about fetch events with cache status. Next.js does not expose “cache hit vs origin” for fetch() in a way APM monitoring can see by default. This could be possible if you can make it visible with custom APM labels / spans.

Ideas:

• Make adding event listeners possible for get and set methods for createRedisHandler
• Add extra headers into responses from Redis what fetch can see, like x-nextjs-cache-handler: HIT

[KajSzy]

I think as far as you are using SSG it's should be aligned with x-nextjs-cache header value

[haapti]

I think as far as you are using SSG it's should be aligned with x-nextjs-cache header value

On my project im only using data caching and dynamic rendering. Therefore i would not get x-nextjs-cache response headers from nextjs server.

On my comment im talking about debugging what happens between nextjs server (fetch) and cache provider (redis). Only when running nextjs in dev mode it is possible to see how each fetch request is handled.

[KajSzy]

Try setting truthy value for NEXT_PRIVATE_DEBUG_CACHE, this should enable a lot of console logs related to cache-handler
https://github.com/fortedigital/nextjs-cache-handler/blob/master/packages/nextjs-cache-handler/src/handlers/cache-handler.ts#L134