feat: Add a way to filter our some paths

[ltouati]

When using the rocket file server, a lot of transactions are sent to sentry. Adds a configuration parameter to filter a series of paths

[Hugo-C]

I am also interrested in this feature !
I'll take a look at the PR.
Did you see/try trace_sampler ? It could be a viable option that is more flexible but I didn't find an example on how to use it yet.

[intgr]

Sentry documentation describes a traces_sampler callback function which can make decisions about which transactions get sampled and at what rate.

https://docs.sentry.io/platforms/rust/configuration/sampling/

The documentation says it's not supported by Rust yet, but looks like a few relevant pull requests have actually been merged, maybe the documentation is just outdated.

• sentry-core: add traces_sampler client option getsentry/sentry-rust#510
• sentry-core: support custom user data in TransactionContext getsentry/sentry-rust#512

That seems like a more flexible approach. And if Sentry SDK already provides similar functionality, it's best not to duplicate it.

[intgr]

Ah sorry, Hugo-C already mentioned traces_sampler. I hadn't read his comment yet :)

[Hugo-C]

The traces_sampler does work (tested here). Ideally we have to find a way for users to set it on fairing initialisation, maybe something like Rocket's Shield ? So some big changes on how RocketSentry have to be initialized 😅
The big plus of traces_sampler is that indeed it allows to set a lower rate instead of completely filter it out.

[Hugo-C]

If no one plans to work on this ticket, I'll give it a go next week