aws-smithy-http-server - http/1 support #4373

drganjoo · 2025-10-31T22:00:01Z

This PR migrates aws-smithy-http-server from [email protected]/[email protected] to [email protected]/[email protected].

Background

This is the second PR in the HTTP 1.x migration series:

✅ Legacy crates PR - Added aws-smithy-legacy-http and aws-smithy-legacy-http-server for [email protected] support
👉 This PR - Upgrade aws-smithy-http-server to [email protected]/[email protected]
🔜 Codegen changes - Add http-1x flag and conditional dependency logic

Key Changes

1. Dependency Upgrades

http: 0.2.9 → 1.x
http-body: 0.4.5 → 1.0
hyper: 0.14.26 → 1.x (with server, http1, http2 features)
hyper-util: Added 0.1 for server utilities (server-auto, server-graceful, etc.)
http-body-util: Added 0.1 for body utilities
tower-http: 0.3 → 0.6
lambda_http: 0.8.4 → 0.17 (for AWS Lambda support)

Updated aws-smithy-types to use http-body-1-x feature instead of http-body-0-4-x.

2. New `serve` Module

Added a comprehensive serve module (inspired by axum::serve) that provides:

Simple server API: Ergonomic serve(listener, service) function
Flexible listeners: Listener trait supporting TCP, Unix sockets, and custom transports
Connection limiting: Built-in limit_connections() via ListenerExt
Graceful shutdown: Zero-cost when unused, opt-in with .with_graceful_shutdown()
Hyper customization: .configure_hyper() for protocol and performance tuning
Comprehensive docs: Examples, troubleshooting, and advanced patterns

Files: src/serve/mod.rs (794 lines), src/serve/listener.rs (269 lines)

3. API Updates Throughout

Updated all modules to work with [email protected] APIs:

body.rs: Enhanced to work with [email protected] traits (+176 lines)
routing/lambda_handler.rs: Updated for [email protected] (+299 lines)
layer/alb_health_check.rs: Adapted for new HTTP types (+150 lines)
protocol modules: Updated all protocol implementations (REST JSON, AWS JSON, REST XML, RPC v2 CBOR)
rejection/error types: Added implementations for [email protected] error types

4. Comprehensive Testing

serve_integration_test.rs: 812 lines of integration tests for the serve module
graceful_shutdown_test.rs: 211 lines testing graceful shutdown scenarios
Tests verify HTTP/1, HTTP/2, connection limits, graceful shutdown, and error handling

Migration Impact

Breaking Change: This updates the public API to use [email protected] types (http::Request, http::Response, etc.).

Users will need to:

Update their dependencies to use [email protected]
Use the new serve() API or update to [email protected] connection APIs
Update any code working directly with HTTP types

Benefits

Modern ecosystem: Aligns with the latest Rust HTTP ecosystem
Better ergonomics: New serve module provides simpler server setup
Performance: Benefits from [email protected] performance improvements
Maintainability: No need to maintain compatibility with deprecated versions
Feature completeness: Graceful shutdown, connection limiting, and flexible configuration

Testing

✅ Integration tests cover major scenarios
✅ Graceful shutdown tested
✅ All protocol implementations verified

Next Steps

The next PR will update the codegen to conditionally generate code that uses either:

aws-smithy-legacy-http-server (for [email protected] - default)
aws-smithy-http-server (for [email protected] - when http-1x flag enabled)

rcoh · 2025-11-03T15:45:38Z

rust-runtime/aws-smithy-http-server/Cargo.toml

 uuid = { version = "1.1.2", features = ["v4", "fast-rng"], optional = true }

 [dev-dependencies]
+aws-smithy-legacy-http-server = { path = "../aws-smithy-legacy-http-server" }


I'm sure I'll find out but...why do we have this dependency?

This dependency along with its benchmark, needs to be removed. While it was initially added to include some AI-generated benchmarking, the generated benchmark needs significant improvement. However, I'd prefer not to delay this PR further by waiting for a proper benchmark framework to be implemented.

rcoh · 2025-11-03T15:46:42Z

rust-runtime/aws-smithy-http-server/benches/compare_hyper_versions.rs

+    println!("════════════════════════════════════════════════════════════");
+    println!();
+    println!("📊 Summary");
+    println!("────────────────────────────────────────────────────────────");
+    println!();
+
+    let speedup = new_results.requests_per_sec / legacy_results.requests_per_sec;
+    let latency_improvement = (legacy_results.avg_latency_micros - new_results.avg_latency_micros)
+        / legacy_results.avg_latency_micros * 100.0;
+
+    println!("  Legacy (hyper 0.14):   {:.2} req/s", legacy_results.requests_per_sec);
+    println!("  New (hyper 1.x):       {:.2} req/s", new_results.requests_per_sec);
+    println!();
+    println!("  Throughput change:     {:.2}% ({:.2}x)", (speedup - 1.0) * 100.0, speedup);
+    println!("  Latency improvement:   {:.2}%", latency_improvement);
+    println!();
+
+    if speedup > 1.01 {
+        println!("  ✅ New server is faster!");
+    } else if speedup < 0.99 {
+        println!("  ⚠️  Legacy server was faster");
+    } else {
+        println!("  ≈  Performance is similar");
+    }
+    println!();
+    println!("════════════════════════════════════════════════════════════");
+


this is actually...a scientific comparison / load test or anything

rcoh · 2025-11-03T15:49:02Z

rust-runtime/aws-smithy-http-server/examples/connection_limiting.rs

+    // The listener limits concurrent connections to 100.
+    // Once 100 connections are active, new connections will wait at the OS level
+    // until an existing connection completes.
+    let listener = TcpListener::bind("0.0.0.0:3000").await?.limit_connections(100);


huh...I wonder if we want an extension trait here or something more explicit.

It comes from ListenerExt imported at the top—happy to hear what you had in mind for making it more explicit.

rcoh · 2025-11-03T15:50:46Z

rust-runtime/aws-smithy-http-server/examples/request_concurrency_limiting.rs

+
+    // Limit concurrent requests at the application level
+    let app = ServiceBuilder::new()
+        .layer(ConcurrencyLimitLayer::new(50))


We should NEVER have examples of ConcurrencyLimit that are not combined with LoadShed because it leads to memory / connection leaks otherwise.

You're absolutely right about this. I'll remove the example entirely—the intent was to show how to apply a Tower layer, but this topic really belongs in a dedicated production hardening guide, not as a standalone example suggesting there's a 'one size fits all' solution.

rcoh · 2025-11-03T15:52:31Z

rust-runtime/aws-smithy-http-server/examples/serve_comparison.rs

+//! Example comparing handle_connection vs handle_connection_strategy performance.
+//!
+//! This example starts a simple HTTP server that responds with "Hello, World!"
+//! and can be load tested with tools like `oha`.
+//!
+//! Usage:
+//!   # Run with strategy pattern implementation (uses handle_connection_strategy)
+//!   cargo run --example serve_comparison --release
+//!
+//!   # Then in another terminal, run load test:
+//!   oha -z 30s -c 100 http://127.0.0.1:3000/
+//!
+//! To test the original branching implementation, you would need to modify
+//! the serve module to export handle_connection and use it here.


this doesn't appear to be comparing anything?

You're right, the name is misleading—it's not actually comparing anything. This was just being used to test the server independently against workloads using oha/wrk. I'll remove it.

rcoh · 2025-11-04T21:49:55Z

rust-runtime/aws-smithy-http-server/examples/request_id.rs

+#![cfg_attr(
+    not(feature = "request-id"),
+    allow(unused_imports, dead_code, unreachable_code)
+)]


I think you can cfg out the entire example? Or can you not because its an example and not a module?

Fahad Zubair added 5 commits October 31, 2025 19:43

Add aws-smithy-http-server - http@1 support

23aa48a

Update docs and tests

5659608

Use crate::http

c1c3faf

Use crate::http throughout

97dd8f7

fix docs

6b02aea

drganjoo requested a review from a team as a code owner October 31, 2025 22:00

Fix docs and cargo fmt

892eb10

drganjoo requested a review from a team as a code owner November 1, 2025 09:13

Fahad Zubair added 2 commits November 2, 2025 20:49

Update gracefulshutdown to support coordinator

89edd58

Remove strategy based traits and use plain branching

a373d35

rcoh reviewed Nov 3, 2025

View reviewed changes

Removed benches, and other non-necessary examples

9f88057

rcoh reviewed Nov 4, 2025

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drganjoo commented Oct 31, 2025

Background

Key Changes

1. Dependency Upgrades

2. New serve Module

3. API Updates Throughout

4. Comprehensive Testing

Migration Impact

Benefits

Testing

Next Steps

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2. New `serve` Module