Is it possible to somehow define Slack request signature verfiying in Smithy?

[x1a0]

I am very new to Smithy and want to create a service that will receive requests from Slack.
Slack supports request verifying: https://api.slack.com/authentication/verifying-requests-from-slack.
In short, it needs 2 values from HTTP header, plus the whole HTTP body, as input, to calculate the signature.

I wonder is it possible to define this as some sort of Smithy trait. So I can have something like:

@slackSig
@http(method: "POST", uri: "/slack/event")
operation SlackEvent {
    input: SlackEventInput
}

Then the Rust code generator generates some Rust trait that I could implement, to have the actual Slack signature verifying logic. In the end, an instance of the verifier is created and attached to the service.

[david-perez]

smithy-rs doesn't have such a general mechanism to pre-apply a middleware based on a trait in the Smithy data model. We do plan on supporting such a mechanism, but the author of the Smithy trait will have to provide a small code-generation component: essentially, they will have to fill one of these out:

smithy-rs/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/generators/ServiceConfigGenerator.kt

Lines 25 to 29 in f0929e7

	/**
	* Contains all data necessary to render a method on the config builder object to apply arbitrary layers, HTTP plugins,
	* and model plugins.
	*/
	data class ConfigMethod(

Iin your mind, how did you envision the code generator to generate such a Rust trait just from the @slackSig Smithy trait? Presumably you'll need to tell it somehow on which struct the trait should be implemented, what are its methods, etc?