Delegate stub webserver to mod web.

Add prometheus monitoring.

src/main.rs

@@ -17,6 +17,8 @@ use reqwest;
 use structopt::StructOpt;
 use yup_oauth2::{Authenticator, InstalledFlow};
 
+mod web;
+
 #[derive(Debug, StructOpt)]
 enum Command {
     /// List albums for the user of the given credentials.  Optionally title filter.
@@ -285,8 +287,9 @@ fn list_albums(
         })
         .collect())
 }
+
 pub fn serve(addr: SocketAddr, root: PathBuf) -> Result<(), Box<dyn Error>> {
-    Ok(())
+    web::run(addr, root)
 }
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {

src/web.rs

@@ -0,0 +1,47 @@
+use std::error::Error;
+use std::net::SocketAddr;
+use std::path::PathBuf;
+
+use prometheus::Encoder;
+use warp;
+use warp::http::header::{HeaderMap, HeaderValue};
+use warp::reject::Rejection;
+use warp::Filter;
+
+fn metrics() -> impl Filter<Extract = (impl warp::reply::Reply,), Error = Rejection> + Clone {
+    let mut text_headers = HeaderMap::new();
+    text_headers.insert("content-type", HeaderValue::from_static("text/plain"));
+    warp::path("metrics")
+        .map(|| {
+            let mut buffer = Vec::new();
+            let encoder = prometheus::TextEncoder::new();
+
+            // Gather the metrics.
+            let metric_families = prometheus::gather();
+            // Encode them to send.
+            encoder.encode(&metric_families, &mut buffer).unwrap();
+            // TODO(wathiede): see if there's a wrapper like html()
+            buffer
+        })
+        .with(warp::reply::with::headers(text_headers))
+}
+
+fn index() -> Result<impl warp::Reply, warp::Rejection> {
+    Ok("Hello world")
+}
+
+pub fn run(addr: SocketAddr, root: PathBuf) -> Result<(), Box<dyn Error>> {
+    let index = warp::path::end().and_then(index);
+
+    // Fallback, always keep this last.
+    //let api = api.or(index);
+    let api = index;
+
+    let api = api.with(warp::log("moviewatcher"));
+    // We don't want metrics & heath checking filling up the logs, so we add this handler after
+    // wrapping with the log filter.
+    let routes = metrics().or(api);
+
+    warp::serve(routes).run(addr);
+    Ok(())
+}