Update Metric.scala

server/core/src/main/scala/sttp/tapir/server/metrics/Metric.scala

@@ -63,4 +63,25 @@ object MetricLabels {
       }
     )
   )
+
+  /** Default labels for OpenTelemetry-compliant metrics, as recommended here:
+    * https://opentelemetry.io/docs/specs/semconv/http/http-metrics/#http-server
+    *
+    *   - `http.request.method` - HTTP request method (e.g., GET, POST).
+    *   - `path` - The request path or route template.
+    *   - `http.response.status_code` - HTTP response status code (200, 404, etc.).
+    */
+  lazy val OpenTelemetryAttributes: MetricLabels = MetricLabels(
+    forRequest = List(
+      "http.request.method" -> { case (_, req) => req.method.method },
+      "path" -> { case (ep, _) => ep.showPathTemplate(showQueryParam = None) }
+    ),
+    forResponse = List(
+      "http.response.status_code" -> {
+        case Right(r) => r.code.code.toString
+        // Default to 500 for exceptions
+        case Left(_) => "500"
+      }
+    )
+  )
 }