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#![warn(missing_docs)] //#![deny(warnings)] //! Enriches the `lambda` crate with [`http`](https://github.com/hyperium/http) //! types targeting AWS [ALB](https://docs.aws.amazon.com/elasticloadbalancing/latest/application/introduction.html), [API Gateway](https://docs.aws.amazon.com/apigateway/latest/developerguide/welcome.html) REST and HTTP API lambda integrations. //! //! This crate abstracts over all of these trigger events using standard [`http`](https://github.com/hyperium/http) types minimizing the mental overhead //! of understanding the nuances and variation between trigger details allowing you to focus more on your application while also giving you to the maximum flexibility to //! transparently use whichever lambda trigger suits your application and cost optimiztions best. //! //! # Examples //! //! ## Hello World //! //! The following example is how you would structure your Lambda such that you have a `main` function where you explicitly invoke //! `lambda_runtime::run` in combination with the [`handler`](fn.handler.html) function. This pattern allows you to utilize global initialization //! of tools such as loggers, to use on warm invokes to the same Lambda function after the first request, helping to reduce the latency of //! your function's execution path. //! //! ```rust,no_run //! use lambda_http::{handler, lambda_runtime::{self, Error}}; //! //! #[tokio::main] //! async fn main() -> Result<(), Error> { //! // initialize dependencies once here for the lifetime of your //! // lambda task //! lambda_runtime::run(handler(|request, context| async { Ok("👋 world!") })).await?; //! Ok(()) //! } //! ``` //! //! ## Leveraging trigger provided data //! //! You can also access information provided directly from the underlying trigger events, like query string parameters, //! with the [`RequestExt`](trait.RequestExt.html) trait. //! //! ```rust,no_run //! use lambda_http::{handler, lambda_runtime::{self, Context, Error}, IntoResponse, Request, RequestExt}; //! //! #[tokio::main] //! async fn main() -> Result<(), Error> { //! lambda_runtime::run(handler(hello)).await?; //! Ok(()) //! } //! //! async fn hello( //! request: Request, //! _: Context //! ) -> Result<impl IntoResponse, Error> { //! Ok(format!( //! "hello {}", //! request //! .query_string_parameters() //! .get("name") //! .unwrap_or_else(|| "stranger") //! )) //! } //! ``` // only externed because maplit doesn't seem to play well with 2018 edition imports #[cfg(test)] #[macro_use] extern crate maplit; pub use http::{self, Response}; pub use lambda_runtime::{self, Context}; use lambda_runtime::{Error, Handler as LambdaHandler}; mod body; pub mod ext; pub mod request; #[doc(hidden)] pub mod response; mod strmap; pub use crate::{body::Body, ext::RequestExt, response::IntoResponse, strmap::StrMap}; use crate::{ request::{LambdaRequest, RequestOrigin}, response::LambdaResponse, }; use std::{ future::Future, pin::Pin, task::{Context as TaskContext, Poll}, }; /// Type alias for `http::Request`s with a fixed [`Body`](enum.Body.html) type pub type Request = http::Request<Body>; /// Functions serving as ALB and API Gateway REST and HTTP API handlers must conform to this type. /// /// This can be viewed as a `lambda_runtime::Handler` constrained to `http` crate `Request` and `Response` types pub trait Handler: Sized { /// The type of Error that this Handler will return type Error; /// The type of Response this Handler will return type Response: IntoResponse; /// The type of Future this Handler will return type Fut: Future<Output = Result<Self::Response, Self::Error>> + Send + 'static; /// Function used to execute handler behavior fn call(&self, event: Request, context: Context) -> Self::Fut; } /// Adapts a [`Handler`](trait.Handler.html) to the `lambda_runtime::run` interface pub fn handler<H: Handler>(handler: H) -> Adapter<H> { Adapter { handler } } /// An implementation of `Handler` for a given closure return a `Future` representing the computed response impl<F, R, Fut> Handler for F where F: Fn(Request, Context) -> Fut, R: IntoResponse, Fut: Future<Output = Result<R, Error>> + Send + 'static, { type Response = R; type Error = Error; type Fut = Fut; fn call(&self, event: Request, context: Context) -> Self::Fut { (self)(event, context) } } #[doc(hidden)] pub struct TransformResponse<R, E> { request_origin: RequestOrigin, fut: Pin<Box<dyn Future<Output = Result<R, E>> + Send>>, } impl<R, E> Future for TransformResponse<R, E> where R: IntoResponse, { type Output = Result<LambdaResponse, E>; fn poll(mut self: Pin<&mut Self>, cx: &mut TaskContext) -> Poll<Self::Output> { match self.fut.as_mut().poll(cx) { Poll::Ready(result) => Poll::Ready( result.map(|resp| LambdaResponse::from_response(&self.request_origin, resp.into_response())), ), Poll::Pending => Poll::Pending, } } } /// Exists only to satisfy the trait cover rule for `lambda_runtime::Handler` impl /// /// User code should never need to interact with this type directly. Since `Adapter` implements `Handler` /// It serves as a opaque trait covering type. /// /// See [this article](http://smallcultfollowing.com/babysteps/blog/2015/01/14/little-orphan-impls/) /// for a larger explaination of why this is nessessary pub struct Adapter<H: Handler> { handler: H, } impl<H: Handler> Handler for Adapter<H> { type Response = H::Response; type Error = H::Error; type Fut = H::Fut; fn call(&self, event: Request, context: Context) -> Self::Fut { self.handler.call(event, context) } } impl<H: Handler> LambdaHandler<LambdaRequest<'_>, LambdaResponse> for Adapter<H> { type Error = H::Error; type Fut = TransformResponse<H::Response, Self::Error>; fn call(&self, event: LambdaRequest<'_>, context: Context) -> Self::Fut { let request_origin = event.request_origin(); let fut = Box::pin(self.handler.call(event.into(), context)); TransformResponse { request_origin, fut } } }