Add README files for the new crates.

Signed-off-by: David Calavera <[email protected]>

Author: calavera

README.md

@@ -6,6 +6,9 @@ This package makes it easy to run AWS Lambda Functions written in Rust. This wor
 
 - [![Docs](https://docs.rs/lambda_runtime/badge.svg)](https://docs.rs/lambda_runtime) **`lambda-runtime`** is a library that provides a Lambda runtime for applications written in Rust.
 - [![Docs](https://docs.rs/lambda_http/badge.svg)](https://docs.rs/lambda_http) **`lambda-http`** is a library that makes it easy to write API Gateway proxy event focused Lambda functions in Rust.
+- [![Docs](https://docs.rs/lambda_extension/badge.svg)](https://docs.rs/lambda_extension) **`lambda-extension`** is a library that makes it easy to write Lambda Runtime Extensions in Rust.
+- [![Docs](https://docs.rs/lambda_runtime_api_client/badge.svg)](https://docs.rs/lambda_runtime_api_client) **`lambda-runtime-api-client`** is a shared library between the lambda runtime and lambda extension libraries that includes a common API client to talk with the AWS Lambda Runtime API.
+
 
 ## Example function
 

lambda-extension/Cargo.toml

@@ -8,7 +8,7 @@ license = "Apache-2.0"
 repository = "https://github.com/awslabs/aws-lambda-rust-runtime"
 categories = ["web-programming::http-server"]
 keywords = ["AWS", "Lambda", "API"]
-readme = "../README.md"
+readme = "README.md"
 
 [dependencies]
 tokio = { version = "1.0", features = ["macros", "io-util", "sync", "rt-multi-thread"] }

lambda-extension/README.md

@@ -0,0 +1,56 @@
+# Runtime Extensions for AWS Lambda in Rust
+
+[![Docs](https://docs.rs/lambda_extension/badge.svg)](https://docs.rs/lambda_extension)
+
+**`lambda-extension`** is a library that makes it easy to write AWS Lambda Runtime Extensions in Rust.
+
+## Example extension
+
+The code below creates a simple extension that's registered to every `INVOKE` and `SHUTDOWN` events, and logs them in CloudWatch.
+
+```rust,no_run
+use lambda_extension::{extension_fn, Error, NextEvent};
+use log::LevelFilter;
+use simple_logger::SimpleLogger;
+use tracing::info;
+
+async fn log_extension(event: NextEvent) -> Result<(), Error> {
+    match event {
+        NextEvent::Shutdown(event) => {
+            info!("{}", event);
+        }
+        NextEvent::Invoke(event) => {
+            info!("{}", event);
+        }
+    }
+    Ok(())
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    SimpleLogger::new().with_level(LevelFilter::Info).init().unwrap();
+
+    let func = extension_fn(log_extension);
+    lambda_extension::run(func).await
+}
+```
+
+## Deployment
+
+Lambda extensions can be added to your functions either using [Lambda layers](https://docs.aws.amazon.com/lambda/latest/dg/using-extensions.html#using-extensions-config), or adding them to [containers images](https://docs.aws.amazon.com/lambda/latest/dg/using-extensions.html#invocation-extensions-images). Regardless of how you deploy them, the extensions MUST be compiled against the same architecture that your lambda functions runs on. The only two architectures that AWS Lambda supports are `aarch64-unknown-linux-gnu` for ARM functions, and `x86_64-unknown-linux-gnu` for x86 functions.
+
+### Building extensions
+
+Once you've decided which target you'll use, you can install it by running the next `rustup` command:
+
+```bash
+$ rustup target add x86_64-unknown-linux-gnu
+```
+
+Then, you can compile the extension against that target:
+
+```bash
+$ cargo build -p lambda_extension --example basic --release --target x86_64-unknown-linux-gnu
+```
+
+This previous command will generate a binary file in `target/x86_64-unknown-linux-gnu/release/examples` called `basic`. When the extension is registered with the [Runtime Extensions API](https://docs.aws.amazon.com/lambda/latest/dg/runtimes-extensions-api.html#runtimes-extensions-api-reg), that's the name that the extension will be registered with. If you want to register the extension with a different name, you only have to rename this binary file and deploy it with the new name.

lambda-runtime-api-client/Cargo.toml

@@ -8,7 +8,7 @@ license = "Apache-2.0"
 repository = "https://github.com/awslabs/aws-lambda-rust-runtime"
 categories = ["web-programming::http-server"]
 keywords = ["AWS", "Lambda", "API"]
-readme = "../README.md"
+readme = "README.md"
 
 [dependencies]
 http = "0.2"

lambda-runtime-api-client/README.md

@@ -0,0 +1,35 @@
+# AWS Lambda Runtime API Client
+
+[![Docs](https://docs.rs/lambda_runtime_api_client/badge.svg)](https://docs.rs/lambda_runtime_api_client)
+
+**`lambda-runtime-api-client`** is a library to interact with the AWS Lambda Runtime API.
+
+This crate provides simple building blocks to send REST request to this API.
+
+## Example
+
+```rust,no_run
+use http::{Method, Request};
+use hyper::Body;
+use lambda_runtime_api_client::{build_request, Client, Error};
+
+fn register_request(extension_name: &str, events: &[&str]) -> Result<Request<Body>, Error> {
+    let events = serde_json::json!({ "events": events });
+
+    let req = build_request()
+        .method(Method::POST)
+        .uri("/2020-01-01/extension/register")
+        .header("Lambda-Extension-Name", extension_name)
+        .body(Body::from(serde_json::to_string(&events)?))?;
+
+    Ok(req)
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    let client = Client::builder().build()?;
+    let request = register_request("my_extension", &["INVOKE"])?;
+
+    client.call(request).await
+}
+```