Add aws-lambda as a feature to generated server SDK (#3648)

## Motivation and Context
The generated SDK conditionally re-exports `routing::LambdaHandler`
under the feature flag aws-lambda, but the `Cargo.toml` does not define
such a feature.

## Description
Closes: #3643

## Checklist
- [x] I have updated `CHANGELOG.next.toml` if I made changes to the
smithy-rs codegen or runtime crates

---------

Co-authored-by: Fahad Zubair <fahadzub@amazon.com>
Co-authored-by: david-perez <d@vidp.dev>

Author: 3 people

CHANGELOG.next.toml

@@ -9,4 +9,9 @@
 # message = "Fix typos in module documentation for generated crates"
 # references = ["smithy-rs#920"]
 # meta = { "breaking" = false, "tada" = false, "bug" = false, "target" = "client | server | all"}
-# author = "rcoh"
+# author = "rcoh"
+[[smithy-rs]]
+message = "A feature, `aws-lambda`, has been added to generated SDKs to re-export types required for Lambda deployment."
+references = ["smithy-rs#3643"]
+meta = { "breaking" = false, "bug" = true, "tada" = false, "target" = "server" }
+author = "drganjoo"

codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/ServerRequiredCustomizations.kt

@@ -48,6 +48,14 @@ class ServerRequiredCustomizations : ServerCodegenDecorator {
             ),
         )
 
+        rustCrate.mergeFeature(
+            Feature(
+                "aws-lambda",
+                true,
+                listOf("aws-smithy-http-server/aws-lambda"),
+            ),
+        )
+
         rustCrate.withModule(ServerRustModule.Types) {
             pubUseSmithyPrimitives(codegenContext, codegenContext.model, rustCrate)(this)
             rustTemplate(

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

@@ -38,6 +38,11 @@ class ServerRuntimeTypesReExportsGenerator(
             }
             pub mod request {
                 pub use #{SmithyHttpServer}::request::FromParts;
+
+                ##[cfg(feature = "aws-lambda")]
+                pub mod lambda {
+                    pub use #{SmithyHttpServer}::request::lambda::Context;
+                }
             }
             pub mod response {
                 pub use #{SmithyHttpServer}::response::IntoResponse;

examples/pokemon-service-lambda/Cargo.toml

@@ -19,6 +19,6 @@ tracing = "0.1"
 lambda_http = "0.8.0"
 
 # Local paths
-aws-smithy-http-server = { path = "../../rust-runtime/aws-smithy-http-server", features = ["aws-lambda"] }
-pokemon-service-server-sdk = { path = "../pokemon-service-server-sdk/" }
+aws-smithy-http-server = { path = "../../rust-runtime/aws-smithy-http-server" }
+pokemon-service-server-sdk = { path = "../pokemon-service-server-sdk/", features = ["aws-lambda"] }
 pokemon-service-common = { path = "../pokemon-service-common/" }

examples/pokemon-service-lambda/src/lib.rs

@@ -5,13 +5,14 @@
 
 use std::sync::Arc;
 
-use aws_smithy_http_server::{request::lambda::Context, Extension};
+use aws_smithy_http_server::Extension;
 
 use pokemon_service_common::State;
 use pokemon_service_server_sdk::{
     error::{GetStorageError, StorageAccessNotAuthorized},
     input::GetStorageInput,
     output::GetStorageOutput,
+    server::request::lambda::Context,
 };
 
 /// Retrieves the user's storage and logs the lambda request ID.

examples/pokemon-service-lambda/src/main.rs

@@ -5,14 +5,16 @@
 
 use std::sync::Arc;
 
-use aws_smithy_http_server::{routing::LambdaHandler, AddExtensionLayer};
+use aws_smithy_http_server::AddExtensionLayer;
 
 use pokemon_service_common::{
     capture_pokemon, check_health, do_nothing, get_pokemon_species, get_server_statistics,
     setup_tracing, stream_pokemon_radio, State,
 };
 use pokemon_service_lambda::get_storage_lambda;
-use pokemon_service_server_sdk::{PokemonService, PokemonServiceConfig};
+use pokemon_service_server_sdk::{
+    server::routing::LambdaHandler, PokemonService, PokemonServiceConfig,
+};
 
 #[tokio::main]
 pub async fn main() {