Log built-in rejections

[davidpdrsn]

This enables logging of axum's built-in rejections, to make things easier to debug.

I also opted to merge the define_rejection and composite_rejection macros that we had in axum-core and axum. That way we only have to update once place when changing the built-in rejections. Done in a separate commit.

Example output:

2023-04-09T11:43:00.432638Z TRACE http_request{method=GET matched_path="/"}: axum::rejection: rejecting request status=415 body=Expected request with `Content-Type: application/json` rejection_type="axum::extract::rejection::MissingJsonContentType"

TODO

• Implement it for all built-in rejections. Grep for fn body_text.
• Docs, including documenting the feature flags.
• Update tracing example to show filtering for for the axum::rejection target.
• Changelog
• When merged make the tracing feature default in axum, probably not in axum-core.

[jplatte]

Why %?

[davidpdrsn]

Good question 🤔 it's not needed. I've removed it.

[davidpdrsn]

Turns out it was needed after all https://github.com/tokio-rs/axum/actions/runs/4668640604/jobs/8266041087?pr=1890

[jplatte]

Wut? Docs show that the impl exists: https://docs.rs/tracing/latest/tracing/trait.Value.html#impl-Value-for-String

Also, I think the default formatting for str is equivalent to the ?debug formatting rather than %display formatting.

[jplatte]

Let's get more clarity on the %display thing in the tracing event before merging.

[davidpdrsn]

Let's get more clarity on the %display thing in the tracing event before merging.

It's how you tell the tracing macro to use the values Display implementation of an event field for formatting (see https://docs.rs/tracing/latest/tracing/#recording-fields). But actually I notice now it's the MSRV test that fails, which uses minimal dependency versions. So its probably pulling in an old version of tracing which didn't have impl Value for String.

[davidpdrsn]

Yep that seems to have been it. The % is gone!