Add example for autoreloading server development (#449)

Cargo.toml

@@ -43,6 +43,7 @@ pretty_env_logger = "0.3"
 serde_derive = "1.0"
 handlebars = "3.0.0"
 tokio = { version = "0.2", features = ["macros"] }
+listenfd = "0.3"
 
 [features]
 default = ["multipart", "websocket"]

examples/README.md

@@ -35,3 +35,7 @@ Hooray! `warp` also includes built-in support for WebSockets
 ### TLS
 
 - [`tls.rs`](./tls.rs) - can i haz security?
+
+### Autoreloading
+
+- [`autoreload.rs`](./autoreload.rs) - Change some code and watch the server reload automatically!

examples/autoreload.rs

@@ -0,0 +1,38 @@
+#![deny(warnings)]
+use hyper::server::Server;
+use listenfd::ListenFd;
+use std::convert::Infallible;
+use warp::Filter;
+
+extern crate listenfd;
+/// You'll need to install `systemfd` and `cargo-watch`:
+/// ```
+/// cargo install systemfd cargo-watch
+/// ```
+/// And run with:
+/// ```
+/// systemfd --no-pid -s http::3030 -- cargo watch -x 'run --example autoreload'
+/// ```
+#[tokio::main]
+async fn main() {
+    // Match any request and return hello world!
+    let routes = warp::any().map(|| "Hello, World!");
+
+    // hyper let's us build a server from a TcpListener (which will be
+    // useful shortly). Thus, we'll need to convert our `warp::Filter` into
+    // a `hyper::service::MakeService` for use with a `hyper::server::Server`.
+    let svc = warp::service(routes);
+    let make_svc = hyper::service::make_service_fn(|_: _| async move { Ok::<_, Infallible>(svc) });
+
+    let mut listenfd = ListenFd::from_env();
+    // if listenfd doesn't take a TcpListener (i.e. we're not running via
+    // the command above), we fall back to explicitly binding to a given
+    // host:port.
+    let server = if let Some(l) = listenfd.take_tcp_listener(0).unwrap() {
+        Server::from_tcp(l).unwrap()
+    } else {
+        Server::bind(&([127, 0, 0, 1], 3030).into())
+    };
+
+    server.serve(make_svc).await.unwrap();
+}