Warn when sending bare 404 response

itowlson · itowlson · commit 5dfb4290999f · 2024-04-02T12:58:03.000+13:00
Signed-off-by: itowlson &lt;ivan.towlson@fermyon.com&gt;
diff --git a/crates/trigger-http/src/lib.rs b/crates/trigger-http/src/lib.rs
@@ -6,6 +6,7 @@ mod wagi;
 
 use std::{
     collections::HashMap,
+    io::IsTerminal,
     net::{Ipv4Addr, SocketAddr, ToSocketAddrs},
     path::PathBuf,
     str::FromStr,
@@ -246,7 +247,7 @@ impl HttpTrigger {
             return match well_known {
                 "health" => Ok(Response::new(body::full(Bytes::from_static(b"OK")))),
                 "info" => self.app_info(),
-                _ => Self::not_found(),
+                _ => Self::not_found(NotFoundRouteKind::WellKnown),
             };
         }
 
@@ -294,7 +295,7 @@ impl HttpTrigger {
                     }
                 }
             }
-            Err(_) => Self::not_found(),
+            Err(_) => Self::not_found(NotFoundRouteKind::Normal(path.to_string())),
         }
     }
 
@@ -320,7 +321,16 @@ impl HttpTrigger {
     }
 
     /// Creates an HTTP 404 response.
-    fn not_found() -> Result<Response<Body>> {
+    fn not_found(kind: NotFoundRouteKind) -> Result<Response<Body>> {
+        use std::sync::atomic::{AtomicBool, Ordering};
+        static SHOWN_GENERIC_404_WARNING: AtomicBool = AtomicBool::new(false);
+        if let NotFoundRouteKind::Normal(route) = kind {
+            if !SHOWN_GENERIC_404_WARNING.fetch_or(true, Ordering::Relaxed)
+                && std::io::stderr().is_terminal()
+            {
+                terminal::warn!("Request to {route} matched no pattern, and received a generic 404 response. To serve a more informative 404 page, add a catch-all (/...) route.");
+            }
+        }
         Ok(Response::builder()
             .status(StatusCode::NOT_FOUND)
             .body(body::empty())?)
@@ -680,6 +690,12 @@ impl OutboundWasiHttpHandler for HttpRuntimeData {
     }
 }
 
+#[derive(Debug, PartialEq)]
+enum NotFoundRouteKind {
+    Normal(String),
+    WellKnown,
+}
+
 #[cfg(test)]
 mod tests {
     use anyhow::Result;

Original file line number	Diff line number	Diff line change
`@@ -6,6 +6,7 @@ mod wagi;`
`6`	`6`
`7`	`7`	`use std::{`
`8`	`8`	`collections::HashMap,`
	`9`	`+ io::IsTerminal,`
`9`	`10`	`net::{Ipv4Addr, SocketAddr, ToSocketAddrs},`
`10`	`11`	`path::PathBuf,`
`11`	`12`	`str::FromStr,`
`@@ -246,7 +247,7 @@ impl HttpTrigger {`
`246`	`247`	`return match well_known {`
`247`	`248`	`"health" => Ok(Response::new(body::full(Bytes::from_static(b"OK")))),`
`248`	`249`	`"info" => self.app_info(),`
`249`		`- _ => Self::not_found(),`
	`250`	`+ _ => Self::not_found(NotFoundRouteKind::WellKnown),`
`250`	`251`	`};`
`251`	`252`	`}`
`252`	`253`
`@@ -294,7 +295,7 @@ impl HttpTrigger {`
`294`	`295`	`}`
`295`	`296`	`}`
`296`	`297`	`}`
`297`		`- Err(_) => Self::not_found(),`
	`298`	`+ Err(_) => Self::not_found(NotFoundRouteKind::Normal(path.to_string())),`
`298`	`299`	`}`
`299`	`300`	`}`
`300`	`301`
`@@ -320,7 +321,16 @@ impl HttpTrigger {`
`320`	`321`	`}`
`321`	`322`
`322`	`323`	`/// Creates an HTTP 404 response.`
`323`		`- fn not_found() -> Result<Response<Body>> {`
	`324`	`+ fn not_found(kind: NotFoundRouteKind) -> Result<Response<Body>> {`
	`325`	`+ use std::sync::atomic::{AtomicBool, Ordering};`
	`326`	`+ static SHOWN_GENERIC_404_WARNING: AtomicBool = AtomicBool::new(false);`
	`327`	`+ if let NotFoundRouteKind::Normal(route) = kind {`
	`328`	`+ if !SHOWN_GENERIC_404_WARNING.fetch_or(true, Ordering::Relaxed)`
	`329`	`+ && std::io::stderr().is_terminal()`
	`330`	`+ {`
	`331`	`+ terminal::warn!("Request to {route} matched no pattern, and received a generic 404 response. To serve a more informative 404 page, add a catch-all (/...) route.");`
	`332`	`+ }`
	`333`	`+ }`
`324`	`334`	`Ok(Response::builder()`
`325`	`335`	`.status(StatusCode::NOT_FOUND)`
`326`	`336`	`.body(body::empty())?)`
`@@ -680,6 +690,12 @@ impl OutboundWasiHttpHandler for HttpRuntimeData {`
`680`	`690`	`}`
`681`	`691`	`}`
`682`	`692`
	`693`	`+#[derive(Debug, PartialEq)]`
	`694`	`+enum NotFoundRouteKind {`
	`695`	`+ Normal(String),`
	`696`	`+ WellKnown,`
	`697`	`+}`
	`698`	`+`
`683`	`699`	`#[cfg(test)]`
`684`	`700`	`mod tests {`
`685`	`701`	`use anyhow::Result;`