Add `AlbHealthCheckLayer` #2540

jjant · 2023-04-04T15:19:18Z

Motivation and Context

Services often need the ability to report health status via health checks (see ALB Health Checks).
This PR adds a simple layer that allows configuring your service to respond to these health check requests.

Description

Adds AlbHealthCheckLayer, and AlbHealthCheckService.

Testing

Added this layer to the pokemon-service binary, and added an integration test for it.

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

rust-runtime/aws-smithy-http-server/src/plugin/check_health.rs

jjant · 2023-04-13T10:21:23Z

rust-runtime/aws-smithy-http-server/src/plugin/check_health.rs

+pin_project! {
+    /// A future that converts `F` into a compatible `S::Future`.
+    pub struct MappedHandlerFuture<R, S, F> {
+        #[pin]
+        inner: F,
+        pd: PhantomData<fn(R) -> S>,
+    }
+}
+
+impl<R, S, F> MappedHandlerFuture<R, S, F> {
+    fn new(inner: F) -> MappedHandlerFuture<R, S, F> {
+        Self { inner, pd: PhantomData }
+    }
+}
+
+impl<R, S: Service<R>, F: Future<Output = S::Response>> Future for MappedHandlerFuture<R, S, F> {
+    type Output = Result<S::Response, S::Error>;
+
+    fn poll(self: std::pin::Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        self.project().inner.poll(cx).map(Ok)
+    }
+}


Is there a simpler way to do this? I basically just want to map HandlerFuture from a Future<Output = Response<BoxBody>> to a Future<Output = Result<Response<BoxBody>, S::Error>>.

I tried using futures_util::future::Map but I ran into a compiler error when trying to write the type in line 92 as (expected function pointer but got function item):

type Future = Either< Map<HandlerFuture, fn(Response<BoxBody) -> Result<Response<BoxBody>, S::Error>>, Oneshot<S, Request<Body>> >;

Add `AlbHealthCheckLayer::new_fn` Make service return a `StatusCode`

rust-runtime/aws-smithy-http-server/src/plugin/alb_health_check.rs

github-actions · 2023-04-21T16:30:48Z

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.

david-perez

Very nice.

david-perez · 2023-04-24T09:27:14Z

rust-runtime/aws-smithy-http-server/src/plugin/alb_health_check.rs

+
+impl AlbHealthCheckLayer<()> {
+    /// Handle health check requests at `health_check_uri` with the specified handler.
+    pub fn from_handler<HandlerFuture: Future<Output = StatusCode>, H: Fn(Request<Body>) -> HandlerFuture + Clone>(


nit: these bounds would read nicer in a where clause.

david-perez · 2023-04-24T09:32:59Z

rust-runtime/aws-smithy-http-server/src/plugin/alb_health_check.rs

+impl<H, S> Service<Request<Body>> for AlbHealthCheckService<H, S>
+where
+    S: Service<Request<Body>, Response = Response<BoxBody>> + Clone,
+    S::Future: std::marker::Send + 'static,


Suggested change

S::Future: std::marker::Send + 'static,

S::Future: Send + 'static,

Send is in the prelude.

## Motivation and Context Services often need the ability to report health status via health checks (see [ALB Health Checks](https://docs.aws.amazon.com/elasticloadbalancing/latest/application/target-group-health-checks.html)). This PR adds a simple layer that allows configuring your service to respond to these health check requests. ## Description Adds `AlbHealthCheckLayer`, and `AlbHealthCheckService`. ## Testing Added this layer to the `pokemon-service` binary, and added an integration test for it. ---- _By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice._

jjant added 4 commits April 4, 2023 15:32

Add Amazon IP header

8374c38

Make types that need to be public public

b746d6c

Use CheckHealthLayer in example

5153fef

Simplify CheckHealthService

ceeb99b

jjant commented Apr 4, 2023

View reviewed changes