Fix catalog service endpoint when querying for a peer service (#22189)

* Fix catalog service endpoint when querying for a peer service

* Add changelog file

* Add changes to docs. Add test

* Update website/content/api-docs/catalog.mdx

Co-authored-by: Jeff Boruszak <[email protected]>

---------

Co-authored-by: Sreeram Narayanan <[email protected]>
Co-authored-by: nitin-sachdev-29 <[email protected]>
Co-authored-by: Jeff Boruszak <[email protected]>

Author: 4 people

.changelog/22189.txt

@@ -0,0 +1,3 @@
+```release-note:improvement
+http: Add peer query param on catalog service API
+```

agent/catalog_endpoint.go

@@ -354,6 +354,8 @@ func (s *HTTPHandlers) catalogServiceNodes(resp http.ResponseWriter, req *http.R
 		return nil, nil
 	}
 
+	s.parsePeerName(req, &args)
+
 	// Check for a tag
 	params := req.URL.Query()
 	if _, ok := params["tag"]; ok {

agent/catalog_endpoint_test.go

@@ -964,6 +964,76 @@ func TestCatalogServiceNodes_Filter(t *testing.T) {
 	require.Len(t, nodes, 1)
 }
 
+func TestCatalogServiceNodes_PeerFilter(t *testing.T) {
+	if testing.Short() {
+		t.Skip("too slow for testing.Short")
+	}
+
+	t.Parallel()
+	a := StartTestAgent(t, TestAgent{HCL: "", Overrides: `peering = { test_allow_peer_registrations = true }`})
+	defer a.Shutdown()
+
+	peerName := "test"
+	queryPath := "/v1/catalog/service/api?filter=" + url.QueryEscape("ServiceMeta.somekey == somevalue") + peerQuerySuffix(peerName)
+
+	// Make sure an empty list is returned, not a nil
+	{
+		req, _ := http.NewRequest("GET", queryPath, nil)
+		resp := httptest.NewRecorder()
+		obj, err := a.srv.CatalogServiceNodes(resp, req)
+		require.NoError(t, err)
+
+		assertIndex(t, resp)
+
+		nodes := obj.(structs.ServiceNodes)
+		require.Empty(t, nodes)
+	}
+
+	// Register node
+	args := &structs.RegisterRequest{
+		Datacenter: "dc1",
+		Node:       "foo",
+		Address:    "127.0.0.1",
+		PeerName:   peerName,
+		Service: &structs.NodeService{
+			Service: "api",
+			Meta: map[string]string{
+				"somekey": "somevalue",
+			},
+		},
+	}
+
+	var out struct{}
+	require.NoError(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
+
+	// Register a second service for the node
+	args = &structs.RegisterRequest{
+		Datacenter: "dc1",
+		Node:       "foo",
+		Address:    "127.0.0.1",
+		PeerName:   peerName,
+		Service: &structs.NodeService{
+			ID:      "api2",
+			Service: "api",
+			Meta: map[string]string{
+				"somekey": "notvalue",
+			},
+		},
+		SkipNodeUpdate: true,
+	}
+
+	require.NoError(t, a.RPC(context.Background(), "Catalog.Register", args, &out))
+
+	req, _ := http.NewRequest("GET", queryPath, nil)
+	resp := httptest.NewRecorder()
+	obj, err := a.srv.CatalogServiceNodes(resp, req)
+	require.NoError(t, err)
+	assertIndex(t, resp)
+
+	nodes := obj.(structs.ServiceNodes)
+	require.Len(t, nodes, 1)
+}
+
 func TestCatalogServiceNodes_WanTranslation(t *testing.T) {
 	if testing.Short() {
 		t.Skip("too slow for testing.Short")

website/content/api-docs/catalog.mdx

@@ -551,6 +551,8 @@ The table below shows this endpoint's support for
 - `filter` `(string: "")` - Specifies the expression used to filter the
   queries results prior to returning the data.
 
+- `peer` `(string: "")` - Specifies the name of the peer that exported the service. Does not apply when no cluster peering connections exist.
+
 - `merge-central-config` - Include this flag in a request for `connect-proxy` kind or `*-gateway` kind
   services to return a fully resolved service definition that includes merged values from the
   [proxy-defaults/global](/consul/docs/connect/config-entries/proxy-defaults) and