Removing generic server instrumentation from `@sentry/nextjs`

[lforst]

The generic server instrumentation in the Next.js SDK contains a lot of code, complexity, and a spoooky side-effect. All of the performance and error instrumentation is already covered by our wrappers.

Upsides:

• Way less code to maintain
• Removes a side effect from the package
• Allows us to simplify our isBuild function

Potential downsides:

• We stop sending certain transactions which may trigger some things in the product (alerts, ...) (See discussion in this issue)
• If people turn off auto-wrapping with instrumentServerFunctions: false they will not send any server-side transactions anymore

[mydea]

It would be great to have a (non-exhaustive) list of things that this would stop from being captured. As of now it is a bit fuzzy to me. Generally, I think this is great, and all for it, but it may be helpful for future reference to know e.g. A, B, and C are not being sent anymore. Do you have a rough idea of what these would be?

[lforst]

It would be great to have a (non-exhaustive) list of things that this would stop from being captured. As of now it is a bit fuzzy to me. Generally, I think this is great, and all for it, but it may be helpful for future reference to know e.g. A, B, and C are not being sent anymore. Do you have a rough idea of what these would be?

Ok after looking at it again, it doesn't seem like we are not sending any fewer transactions as long as our auto wrapping is turned on, which it is by default. I believe I confused the "unnecessary" transactions with some client spans. I updated the issue description to reflect this.

I guess the downside then is that we're not sending any server transactions in case people turn of the auto wrapping with instrumentServerFunctions: false. I think we should still go through with it and fully commit to the auto wrapping and make it work for everybody instead of maintaining these two approaches.

[Lms24]

I guess the downside then is that we're not sending any server transactions in case people turn of the auto wrapping with instrumentServerFunctions: false

Which, I guess one could argue, is what people would expect when setting this option to false, no?

[lforst]

I guess the downside then is that we're not sending any server transactions in case people turn off the auto wrapping with instrumentServerFunctions: false

Which, I guess one could argue, is what people would expect when setting this option to false, no?

I guess so!

As an additional note to give some more insight on in what cases users might have turned instrumentServerFunctions off: We sometimes recommended to turn it off when there is a bug on our side to unblock people. In other cases, we recommended turning it off if other libraries mess with our wrapping. And I believe early on, we recommended turning it off if you hosted your app on Vercel.