[node] Stack locals

[smeubank]

Problem Statement

Node js does not capture stack locals similar to a few other server side SDKs

Stack-locals → Some SDKs (Python and PHP) will pick up variable values within the stacktrace. These can be scrubbed, or this behavior can be disabled altogether if necessary.

comment from an unrelated NextJs issue: #6321 (comment)

Could this be easily applied to remix, next, and any other fromworks depending on Node?

Solution Brainstorm

There are possible concerns in Node that this would create some overhead (if it is possible at all)

If it was to be implemented could it be controlled by some user flag?

[smeubank]

summarizing some internal discussions on this issue in story form:

@lforst found out

• Seems it actually should be possible to access debugger data at runtime with Node Inspector API
  then @AbhiPrasad said
• users essentially must turn on debug mode
• Since you can disable inspect in node
  then @kamilogorek did
• local tests confirm it works on some level

[AbhiPrasad]

@kamilogorek

[kamilogorek]

@kamilogorek

[AbhiPrasad]

[smeubank]

[smeubank]

https://github.com/kamilogorek/sentry-node-local-variables

@kamilogorek example

Refactored everything so its easier to understand

https://github.com/kamilogorek/sentry-node-local-variables/blob/master/vars.js

[timfish]

Oh this is really nice!

[timfish]

How do you want this adding? Keep it as an integration?

Should I do some testing to see how long this suspends the event loop to determine if this can be enabled by default?