Add lambda runtime support

Summary:
This PR adds the support to run the user services on Amazon Lambda

Author: muhamadazmy

Cargo.toml

@@ -22,6 +22,7 @@ default = ["http_server", "rand", "uuid", "tracing-span-filter"]
 hyper = ["dep:hyper", "http-body-util", "restate-sdk-shared-core/http"]
 http_server = ["hyper", "hyper/server", "hyper/http2", "hyper-util", "tokio/net", "tokio/signal", "tokio/macros"]
 tracing-span-filter = ["dep:tracing-subscriber"]
+lambda = [ "dep:http-serde", "dep:lambda_runtime", "dep:aws_lambda_events"]
 
 [dependencies]
 bytes = "1.10"
@@ -43,6 +44,9 @@ tokio = { version = "1.44", default-features = false, features = ["sync"] }
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["registry"], optional = true }
 uuid = { version = "1.16.0", optional = true }
+http-serde = { version = "2.1.1", optional = true }
+aws_lambda_events = { version = "0.16.1", optional = true }
+lambda_runtime = { version = "0.14.2", optional = true }
 
 [dev-dependencies]
 tokio = { version = "1", features = ["full"] }

README.md

@@ -10,11 +10,11 @@
 
 ## Community
 
-* 🤗️ [Join our online community](https://discord.gg/skW3AZ6uGd) for help, sharing feedback and talking to the community.
-* 📖 [Check out our documentation](https://docs.restate.dev) to get quickly started!
-* 📣 [Follow us on Twitter](https://twitter.com/restatedev) for staying up to date.
-* 🙋 [Create a GitHub issue](https://github.com/restatedev/sdk-java/issues) for requesting a new feature or reporting a problem.
-* 🏠 [Visit our GitHub org](https://github.com/restatedev) for exploring other repositories.
+- 🤗️ [Join our online community](https://discord.gg/skW3AZ6uGd) for help, sharing feedback and talking to the community.
+- 📖 [Check out our documentation](https://docs.restate.dev) to get quickly started!
+- 📣 [Follow us on Twitter](https://twitter.com/restatedev) for staying up to date.
+- 🙋 [Create a GitHub issue](https://github.com/restatedev/sdk-java/issues) for requesting a new feature or reporting a problem.
+- 🏠 [Visit our GitHub org](https://github.com/restatedev) for exploring other repositories.
 
 ## Using the SDK
 
@@ -58,6 +58,74 @@ async fn main() {
 }
 ```
 
+## Running on Lambda
+
+The Restate Rust SDK supports running services on AWS Lambda using Lambda Function URLs. This allows you to deploy your Restate services as serverless functions.
+
+### Setup
+
+First, enable the `lambda` feature in your `Cargo.toml`:
+
+```toml
+[dependencies]
+restate-sdk = { version = "0.1", features = ["lambda"] }
+tokio = { version = "1", features = ["full"] }
+```
+
+### Basic Lambda Service
+
+Here's how to create a simple Lambda service:
+
+```rust
+use restate_sdk::prelude::*;
+
+#[restate_sdk::service]
+trait Greeter {
+    async fn greet(name: String) -> HandlerResult<String>;
+}
+
+struct GreeterImpl;
+
+impl Greeter for GreeterImpl {
+    async fn greet(&self, _: Context<'_>, name: String) -> HandlerResult<String> {
+        Ok(format!("Greetings {name}"))
+    }
+}
+
+#[tokio::main]
+async fn main() {
+    // To enable logging/tracing
+    // tracing_subscriber::fmt::init();
+
+    // Build and run the Lambda endpoint
+    Endpoint::builder()
+        .bind(GreeterImpl.serve())
+        .build_lambda()
+        .run()
+        .await
+        .unwrap();
+}
+```
+
+### Deployment
+
+1. Install `cargo-lambda`
+   ```
+   cargo install cargo-lambda
+   ```
+2. Build your Lambda function:
+
+   ```bash
+   cargo lambda build --release --arm64 --output-format zip
+   ```
+
+3. Create a Lambda function with the following configuration:
+
+   - **Runtime**: Amazon Linux 2023
+   - **Architecture**: arm64
+
+4. Upload your `zip` file to the Lambda function.
+
 ### Logging
 
 The SDK uses tokio's [`tracing`](https://docs.rs/tracing/latest/tracing/) crate to generate logs.
@@ -121,15 +189,15 @@ The Rust SDK is currently in active development, and might break across releases
 
 The compatibility with Restate is described in the following table:
 
-| Restate Server\sdk-rust | 0.0 - 0.2 | 0.3 | 0.4 - 0.5 | 0.6              |
-|-------------------------|-----------|-----|-----------|------------------|
-| 1.0                     | ✅         | ❌   | ❌         | ❌                |
-| 1.1                     | ✅         | ✅   | ❌         | ❌                |
-| 1.2                     | ✅         | ✅   | ❌         | ❌                |
-| 1.3                     | ✅         | ✅   | ✅         | ✅ <sup>(1)</sup> |
-| 1.4                     | ✅         | ✅   | ✅         | ✅                |
+| Restate Server\sdk-rust | 0.0 - 0.2 | 0.3 | 0.4 - 0.5 | 0.6               |
+| ----------------------- | --------- | --- | --------- | ----------------- |
+| 1.0                     | ✅        | ❌  | ❌        | ❌                |
+| 1.1                     | ✅        | ✅  | ❌        | ❌                |
+| 1.2                     | ✅        | ✅  | ❌        | ❌                |
+| 1.3                     | ✅        | ✅  | ✅        | ✅ <sup>(1)</sup> |
+| 1.4                     | ✅        | ✅  | ✅        | ✅                |
 
-<sup>(1)</sup> **Note** `bind_with_options` works only from Restate 1.4 onward. 
+<sup>(1)</sup> **Note** `bind_with_options` works only from Restate 1.4 onward.
 
 ## Contributing
 

src/endpoint/mod.rs

@@ -43,6 +43,7 @@ pub struct InputReceiver(InputReceiverInner);
 enum InputReceiverInner {
     Channel(tokio::sync::mpsc::UnboundedReceiver<Result<Bytes, BoxError>>),
     BoxedStream(Pin<Box<dyn Stream<Item = Result<Bytes, BoxError>> + Send + 'static>>),
+    Bytes(Option<Bytes>),
 }
 
 impl InputReceiver {
@@ -54,6 +55,10 @@ impl InputReceiver {
         Self(InputReceiverInner::Channel(rx))
     }
 
+    pub fn from_bytes(b: Bytes) -> Self {
+        Self(InputReceiverInner::Bytes(Some(b)))
+    }
+
     async fn recv(&mut self) -> Option<Result<Bytes, BoxError>> {
         poll_fn(|cx| self.poll_recv(cx)).await
     }
@@ -62,6 +67,7 @@ impl InputReceiver {
         match &mut self.0 {
             InputReceiverInner::Channel(ch) => ch.poll_recv(cx),
             InputReceiverInner::BoxedStream(s) => s.poll_next_unpin(cx),
+            InputReceiverInner::Bytes(b) => Poll::Ready(b.take().map(Ok)),
         }
     }
 }
@@ -440,6 +446,12 @@ impl Builder {
             identity_verifier: self.identity_verifier,
         }))
     }
+
+    #[cfg(feature = "lambda")]
+    pub fn build_lambda(mut self) -> crate::lambda::LambdaEndpoint {
+        self.discovery.protocol_mode = Some(crate::discovery::ProtocolMode::RequestResponse);
+        crate::lambda::LambdaEndpoint::new(self.build())
+    }
 }
 
 /// This struct encapsulates all the business logic to handle incoming requests to the SDK,