RFC: Server Request Metrics #4458

jasgin · 2025-12-22T00:46:39Z

Motivation and Context

Description

Testing

Checklist

For changes to the smithy-rs codegen or runtime crates, I have created a changelog entry Markdown file in the .changelog directory, specifying "client," "server," or both in the applies_to key.
For changes to the AWS SDK, generated SDK code, or SDK runtime crates, I have created a changelog entry Markdown file in the .changelog directory, specifying "aws-sdk-rust" in the applies_to key.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

github-actions · 2025-12-22T01:11:44Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
No codegen difference in the Client Test
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

rcoh

Overall seems good.

The RFC could definitely be fleshed out a bit more — I don't totally get how it will work with operation specific metrics etc.

rcoh · 2025-12-27T13:57:48Z

design/src/rfcs/rfc0046_server_request_metrics.md

+    #[smithy_metrics(extension)]
+    #[metrics(flatten)]
+    operation_metrics: OperationMetrics,
+    custom_metric: Option<String>


This is a custom request level metric right?

rcoh · 2025-12-27T13:58:27Z

design/src/rfcs/rfc0046_server_request_metrics.md

+
+The focal struct that users can add to their service as a tower `Layer` for metrics, containing `new` and `builder` methods to get a `MetricsLayer` with the default configuration or a `MetricsLayerBuilder`, respectively. Because the `MetricsLayer` is specific to the struct provided in the type parameter, the `MetricsLayerBuilder` will be a product of the `#[smithy_metrics]` proc macro expansion, responsible for providing methods to customize things like the metrics initialization and setting custom request/response metrics. Contrarily, the `MetricsLayerConfig` along with its builder will be explicitly defined for general configuration not bound to any specific type parameter, such as enabling/disabling default metrics.
+
+Contains a generic type parameter bound by a marker trait with a default of `DefaultMetrics`, which will be a type defined in the library that uses the `#[smithy_metrics]` expansion.


Fleshed out this section in the latest commits

rcoh · 2025-12-27T13:58:46Z

design/src/rfcs/rfc0046_server_request_metrics.md

+
+- `MetricsLayer::new()` for the default metrics and extensions
+
+- `MetricsLayer::<CustomMetrics>::new()` for the default metrics with potential renaming or additional extensions from attribute proc macros


What is custom metrics here?

rcoh · 2025-12-27T13:59:35Z

design/src/rfcs/rfc0046_server_request_metrics.md

+
+A proc macro that can be placed on a metrique metrics struct for purposes such as the addition of default request/response metrics fields, the implementation of a marker trait, and the expansion of a `MetricsLayerBuilder` with concrete type being the annotated struct.
+
+This will also come with `#[smithy_metrics(rename(x = "y"))]` to rename default fields and `#[smithy_metrics(extension)]` to mark struct fields for insertion to the request extensions to be used in custom middleware or operation handlers.


When would you use this rename vs metrique rename?

This rename is for renaming of the out-of-the-box metrics that will get added to a metrics struct as part of the proc macro expansion (e.g. request_id, service_name, operation_name, etc). Since those fields won't be visible, they'd need to be applied at the outer level and then the expansion will apply the actual metrics rename.

rcoh · 2025-12-27T14:01:07Z

design/src/rfcs/rfc0046_server_request_metrics.md

+        .build();
+}
+
+#[smithy_metrics]


Probably nice to have something like #[smithy_metrics::root], #[smithy_metrics:: operation]

Yeah I currently have it like #[smithy_metrics] and #[smithy_metrics(extension)], I can create a bikeshedding thread at the end to flesh these out.

rcoh · 2025-12-27T14:01:35Z

design/src/rfcs/rfc0046_server_request_metrics.md

+
+#[metrics]
+struct OperationMetrics {
+    get_pokemon_species_metrics: Option<String>


Do I need to manually set this?

Yes, this is an example of a user-defined metrics struct for control of metrics in their operation handlers

aajtodd · 2026-01-05T14:24:10Z

This seems specific to metrique, was there not consideration given to our own runtime observability API: https://github.com/smithy-lang/smithy-rs/tree/main/rust-runtime/aws-smithy-observability

jasgin · 2026-01-09T15:37:13Z

Added some more content to the RFC explaining some of the open questions, and added a preliminary implementation of the metrics layer interface.

Yes the design only has metrique in mind. Maybe future scope can extend to aws-smithy-observability as well.

github-actions · 2026-01-09T15:49:21Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

github-actions · 2026-01-09T16:57:26Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

github-actions · 2026-01-10T18:53:35Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

github-actions · 2026-01-10T20:46:49Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

github-actions · 2026-01-11T22:01:42Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
Server Test Python (ignoring whitespace)
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

github-actions · 2026-01-12T01:21:12Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

github-actions · 2026-01-12T02:05:25Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

github-actions · 2026-01-12T05:11:48Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

github-actions · 2026-01-12T14:28:39Z

A new generated diff is ready to view.

No codegen difference in the AWS SDK
Client Test (ignoring whitespace)
No codegen difference in the Server Test
No codegen difference in the Server Test Python
No codegen difference in the Server Test Typescript

A new doc preview is ready to view.

jasgin requested review from a team as code owners December 22, 2025 00:46

rcoh approved these changes Dec 27, 2025

View reviewed changes

jasgin added 11 commits January 8, 2026 15:37

Add rfc0046_server_request_metrics.md

992aca3

initial commit

f67e086

Add builder

a7934da

Support any sink type

a104408

Improve with typestate builder and easy defaults

f6fb9e7

Refactor

15a02bf

Add plugin for operation level metrics

8b5100a

Clean up

0bbf08a

Use generic implementation of closures

a588567

Simplify metrics layer

5b114bf

Update RFC

860daae

jasgin force-pushed the rfc0046_server_request_metrics branch from 5ebaf8b to 860daae Compare January 9, 2026 15:27

jasgin added 2 commits January 9, 2026 10:49

Pin metrique versions for MSRV

2a1b43a

Add README to aws-smithy-http-server-metrics

a96843b

jasgin added 2 commits January 9, 2026 14:26

Simplify by removing granular default metrics enablement for now

deba788

Move default metrics to plugin for full OOTB possibility

de49d6b

temp

4315ce8

jasgin force-pushed the rfc0046_server_request_metrics branch 3 times, most recently from 0dde16e to 0b97c30 Compare January 11, 2026 21:05

Add toggleable default metrics

5654ba7

jasgin force-pushed the rfc0046_server_request_metrics branch from 0b97c30 to 5654ba7 Compare January 11, 2026 21:10

jasgin added 2 commits January 11, 2026 16:16

Update RFC

74b086a

Handle default case when global sink has not been installed

ec9f005

Error handling for default sink and docs

c506136

jasgin force-pushed the rfc0046_server_request_metrics branch from 3c5802d to c506136 Compare January 12, 2026 00:59

jasgin added 3 commits January 11, 2026 23:10

Add states to builder to allow capturable closures

6f76c36

Add state tests to builder

9829cdd

Add declarative macros for typestate pattern

a6c26fb

jasgin force-pushed the rfc0046_server_request_metrics branch from ba8bcac to a6c26fb Compare January 12, 2026 04:24

Update RFC

900c1ee

Remove unused umport

1fdb9fe

jasgin force-pushed the rfc0046_server_request_metrics branch from b6a1b9b to 1fdb9fe Compare January 12, 2026 14:02


		The focal struct that users can add to their service as a tower `Layer` for metrics, containing `new` and `builder` methods to get a `MetricsLayer` with the default configuration or a `MetricsLayerBuilder`, respectively. Because the `MetricsLayer` is specific to the struct provided in the type parameter, the `MetricsLayerBuilder` will be a product of the `#[smithy_metrics]` proc macro expansion, responsible for providing methods to customize things like the metrics initialization and setting custom request/response metrics. Contrarily, the `MetricsLayerConfig` along with its builder will be explicitly defined for general configuration not bound to any specific type parameter, such as enabling/disabling default metrics.

		Contains a generic type parameter bound by a marker trait with a default of `DefaultMetrics`, which will be a type defined in the library that uses the `#[smithy_metrics]` expansion.


		- `MetricsLayer::new()` for the default metrics and extensions

		- `MetricsLayer::<CustomMetrics>::new()` for the default metrics with potential renaming or additional extensions from attribute proc macros


		A proc macro that can be placed on a metrique metrics struct for purposes such as the addition of default request/response metrics fields, the implementation of a marker trait, and the expansion of a `MetricsLayerBuilder` with concrete type being the annotated struct.

		This will also come with `#[smithy_metrics(rename(x = "y"))]` to rename default fields and `#[smithy_metrics(extension)]` to mark struct fields for insertion to the request extensions to be used in custom middleware or operation handlers.

RFC: Server Request Metrics #4458

Are you sure you want to change the base?

RFC: Server Request Metrics #4458

Conversation

jasgin commented Dec 22, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Motivation and Context

Description

Testing

Checklist

Uh oh!

github-actions bot commented Dec 22, 2025

Uh oh!

rcoh left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

jasgin Jan 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

aajtodd commented Jan 5, 2026

Uh oh!

jasgin commented Jan 9, 2026

Uh oh!

github-actions bot commented Jan 9, 2026

Uh oh!

github-actions bot commented Jan 9, 2026

Uh oh!

github-actions bot commented Jan 10, 2026

Uh oh!

github-actions bot commented Jan 10, 2026

Uh oh!

github-actions bot commented Jan 11, 2026

Uh oh!

github-actions bot commented Jan 12, 2026

Uh oh!

github-actions bot commented Jan 12, 2026

Uh oh!

github-actions bot commented Jan 12, 2026

Uh oh!

github-actions bot commented Jan 12, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

jasgin commented Dec 22, 2025 •

edited

Loading

jasgin Jan 9, 2026 •

edited

Loading