outbound: add l5d-dst-canonical to requests with ServiceProfiles (#2383)

PR #2250 removed the `l5d-dst-canonical` header from ServiceProfile
requests. This header is used by the inbound proxy for telemetry
purposes, so removing it and not putting it back broke ServiceProfile
route metrics. This commit adds a layer for setting this header to the
service profile route stack.

We can also add the header for non-ServiceProfile requests if that's
desirable...I'll have to look into whether it is. This commit should, at
least, fix the existing ServiceProfile route metrics.

Fixes #10521

Author: hawkw

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

@@ -68,11 +68,6 @@ enum RouterParams<T: Clone + Debug + Eq + Hash> {
 }
 
 // Only applies to requests with profiles.
-//
-// TODO Add l5d-dst-canonical header to requests.
-//
-// TODO(ver) move this into the endpoint stack so that we can only
-// set this on meshed connections.
 #[derive(Clone, Debug)]
 struct CanonicalDstHeader(NameAddr);
 

linkerd/app/outbound/src/http/logical/profile.rs

@@ -1,6 +1,6 @@
 use super::{
     super::{concrete, retry},
-    Concrete, NoRoute,
+    CanonicalDstHeader, Concrete, NoRoute,
 };
 use crate::{policy, BackendRef, ParentRef, UNKNOWN_META};
 use linkerd_app_core::{
@@ -313,6 +313,18 @@ impl<T> RouteParams<T> {
                         .http_profile_route
                         .to_layer::<classify::Response, _, RouteParams<T>>(),
                 )
+                // Add l5d-dst-canonical header to requests.
+                //
+                // TODO(ver) move this into the endpoint stack so that we can
+                // only set this on meshed connections.
+                .push(
+                    http::NewHeaderFromTarget::<CanonicalDstHeader, _, _>::layer_via(
+                        |rp: &Self| {
+                            let LogicalAddr(addr) = rp.addr.clone();
+                            CanonicalDstHeader(addr)
+                        },
+                    ),
+                )
                 // Sets the per-route response classifier as a request
                 // extension.
                 .push(classify::NewClassify::layer())