chore: make tracing optional

[tottoto]

Resolves #713.

[gituser-rs]

is there any chance of approving this?

[seanmonstar]

It will be, it's just a breaking change.

[incisakura]

Waiting for this PR to be merged.

If anyone is annoyed by h2 (or any other crate) emitting tracing logs but actually useless to them, a temporary workaround is to set the tracing feature "max_level_off," which would prevent the generation of the event log code, potentially improving runtime performance and reducing the binary size.

[dependencies]
# your dependencies here

tracing = { version = "*", default-features = false, features = ["max_level_off", "release_max_level_off"] }

[gaynor-anthropic]

@seanmonstar is there anything that external contributors can do to help move this forward?

Does it makes sense to make it an on-by-default feature to avoid the backwards compatibility issues?

[papa-zakari]

@seanmonstar is there anything that external contributors can do to help move this forward?

Does it makes sense to make it an on-by-default feature to avoid the backwards compatibility issues?

While I can't speak on behalf of the org, I think that this is a great idea @gaynor-anthropic.

Hyper could use default-features = false and enable tracing specifically for the h2 crate with an "internal" feature flag as part of the suite of features enabled as part of http2. This would imply introducing an additional, user-facing feature flag that would enable http2 without tracing.

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Such a change would make a big difference for anyone hesitating to use hyper for anything from telehealth to military communications. Telemetry is often a non-starter for these purposes. Audit processes often start with looking through the dependency graph of an application.

I understand that it may appear as if I'm introducing urgency in the form of moral obligation. That is a fair observation.

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