`ureq` transport layer does not seem to be working

[sanbox-irl]

How do you use Sentry?

Sentry SaaS (sentry.io)

SDK version

v0.46

Steps to reproduce

I'm trying to use the ureq stack instead of the reqwest transport stack, for no reason other than that trim down the dependencies -- we only send one or a few sentry messages in our game's lifespan, and generally only while panicking, so having it use a simple backend makes sense.

I'm doing that by doing:

[dependencies.sentry]
version = "0.46.0"
default-features = false
features = ["backtrace", "panic", "contexts", "ureq"]

This "works" by trimming the async stack out of my Cargo.lock, but my events don't seem to be going through and making it onto my dashboard. Have I set up the backend correctly and my features for it correctly? How else should I diagnose this?

Expected result

I would see an error in my sentry dashboard

Actual result

I do not.

[linear]

RUST-131

[lcian]

Hi @sanbox-irl, thanks for opening the issue.
When using ureq, you will need to additionally enable one of the rustls or native-tls feature flags, otherwise ureq will have no TLS stack to work with. Doing that should solve the problem.
Please let me know if this solves the problem.
As for diagnosing, a way to do that would have been to initialize Sentry with ClientOptions::debug set to true. That way, you would've seen an error about the event failing to send due to missing TLS stack.

We should probably call this out somewhere in the docs.
Besides that, we should update https://github.com/getsentry/sentry-rust/tree/master/sentry#features because it doesn't reflect the real feature flags that are available right now. Possibly there could be a good place to call this out as well.

[sanbox-irl]

reqwest seems to be brought in no matter what if I enable rustls or native-tls. I'm not a web developer at all (only video games, really) so I might be misunderstanding, but isn't ureq supposed to replace reqwest?

[lcian]

@sanbox-irl Yes, exactly, with the configuration

sentry = { version = "0.46.0", default-features =false, features = ["backtrace", "panic", "contexts", "ureq", "rustls"] }

ureq will be used, replacing the default reqwest transport.

You will still see reqwest listed as a dependency in your Cargo.lock due to this bug in Cargo: rust-lang/cargo#10801 and the way our feature flags are structured.
This is how the rustls and native-tls features are defined in sentry:

native-tls = ["dep:native-tls", "reqwest?/default-tls", "ureq?/native-tls"]
rustls = ["dep:rustls", "reqwest?/rustls-tls", "ureq?/rustls"]

Enabling either of these features, will include both reqwest and ureq in your Cargo.lock due to the bug I linked above, regardless of whether you've enabled the reqwest, ureq, or none of these features on your sentry dependency.

Note that the excessive dependencies are included only in Cargo.lock. If you check your target directory, you will be able to confirm that only the selected library will effectively be compiled and produce build artifacts.
So, this bug only bloats up your lockfile, with no other effect beyond that on the sentry crates.

We could work around this by restructuring our feature flags, but that would probably imply a breaking change for everyone that's using default-features = false.
Our flags are structured correctly, so I believe the problem should rather be fixed upstream in cargo.

[sanbox-irl]

good enough for me!