feat: move common connect/timeout errors from sentry to metrics (#471)

Closes #467

src/error.rs

@@ -133,13 +133,16 @@ impl HandlerErrorKind {
     pub fn metric_label(&self) -> Option<&'static str> {
         match self {
             HandlerErrorKind::InvalidUA => Some("request.error.invalid_ua"),
+            // HandlerErrorKind::Reqest(e) if e.is_timeout() || e.is_connect())
+            // metrics emitted elsewhere (in handlers::get_tiles)
             _ => None,
         }
     }
 
     /// Whether this error should trigger a Sentry event
     pub fn is_sentry_event(&self) -> bool {
         !matches!(self, HandlerErrorKind::InvalidUA)
+            && !matches!(self, HandlerErrorKind::Reqwest(e) if e.is_timeout() || e.is_connect())
     }
 
     pub fn as_response_string(&self) -> String {

src/web/handlers.rs

@@ -159,8 +159,6 @@ pub async fn get_tiles(
             Ok(tiles.to_response(settings.cache_control_header))
         }
         Err(e) => {
-            metrics.incr_with_tags("tiles.get.error", Some(&tags));
-
             if matches!(e.kind(), HandlerErrorKind::BadAdmResponse(_)) {
                 // Handle a bad response from ADM specially.
                 // Report it to metrics and sentry, but also store an empty record
@@ -185,6 +183,16 @@ pub async fn get_tiles(
                 return Ok(HttpResponse::NoContent().finish());
             }
 
+            match e.kind() {
+                HandlerErrorKind::Reqwest(e) if e.is_timeout() => tags.add_tag("reason", "timeout"),
+                HandlerErrorKind::Reqwest(e) if e.is_connect() => tags.add_tag("reason", "connect"),
+                _ => (),
+            }
+            if handle.fallback_tiles.is_some() {
+                tags.add_tag("fallback", "true");
+            }
+            metrics.incr_with_tags("tiles.get.error", Some(&tags));
+
             // A general error occurred, try rendering fallback Tiles
             if let Some(tiles) = handle.fallback_tiles {
                 return Ok(fallback_response(settings, &tiles));