test: test dst_labels

linkerd/app/integration/src/tests/telemetry.rs

@@ -622,11 +622,11 @@ mod outbound_dst_labels {
         let (
             Fixture {
                 client,
-                metrics: _metrics,
+                metrics,
                 proxy: _proxy,
                 _profile,
                 dst_tx,
-                labels: _labels,
+                labels,
                 ..
             },
             addr,
@@ -647,6 +647,18 @@ mod outbound_dst_labels {
 
         info!("client.get(/)");
         assert_eq!(client.get("/").await, "hello");
+
+        let labels = labels
+            .label("dst_addr_label", "foo")
+            .label("dst_set_label", "bar");
+
+        for &metric in &[
+            "request_total",
+            "response_total",
+            "response_latency_ms_count",
+        ] {
+            labels.metric(metric).assert_in(&metrics).await;
+        }
     }
 }
 

linkerd/app/outbound/src/http/concrete.rs

@@ -342,18 +342,24 @@ where
     T: svc::Param<Option<http::uri::Authority>>,
 {
     fn param(&self) -> OutboundEndpointLabels {
+        let arc_labels = self.metadata.labels();
         // self.metadata.labels() could return Err in some cases
         // if that case the dst_labels won't carry any value
-        let mut dst_labels = match Arc::try_unwrap(self.metadata.labels()) {
+        let mut dst_labels = match Arc::try_unwrap(arc_labels) {
             Ok(result) => result,
             Err(_e) => BTreeMap::new(),
         };
 
         dst_labels.remove("pod");
         dst_labels.remove("pod_template_hash");
 
+        let label_iterator = match dst_labels.is_empty() {
+            true => dst_labels.iter(),
+            false => arc_labels.iter()
+        };
+
         OutboundEndpointLabels {
-            labels: prefix_labels("dst", dst_labels.iter()),
+            labels: prefix_labels("dst", label_iterator),
             server_id: self.param(),
         }
     }