Stop hiding kubernetes topologies in the backend.

app/api_topologies.go

@@ -18,28 +18,6 @@ var (
 	topologyRegistry = &registry{
 		items: map[string]APITopologyDesc{},
 	}
-	kubernetesTopologies = []APITopologyDesc{
-		{
-			id:       "pods",
-			renderer: render.PodRenderer,
-			Name:     "Pods",
-			Rank:     3,
-			Options: map[string][]APITopologyOption{"system": {
-				{"show", "System pods shown", false, render.FilterNoop},
-				{"hide", "System pods hidden", true, render.FilterSystem},
-			}},
-		},
-		{
-			id:       "pods-by-service",
-			parent:   "pods",
-			renderer: render.PodServiceRenderer,
-			Name:     "by service",
-			Options: map[string][]APITopologyOption{"system": {
-				{"show", "System services shown", false, render.FilterNoop},
-				{"hide", "System services hidden", true, render.FilterSystem},
-			}},
-		},
-	}
 )
 
 func init() {
@@ -106,6 +84,28 @@ func init() {
 			Rank:     4,
 			Options:  map[string][]APITopologyOption{},
 		},
+		APITopologyDesc{
+			id:          "pods",
+			renderer:    render.PodRenderer,
+			Name:        "Pods",
+			Rank:        3,
+			HideIfEmpty: true,
+			Options: map[string][]APITopologyOption{"system": {
+				{"show", "System pods shown", false, render.FilterNoop},
+				{"hide", "System pods hidden", true, render.FilterSystem},
+			}},
+		},
+		APITopologyDesc{
+			id:          "pods-by-service",
+			parent:      "pods",
+			renderer:    render.PodServiceRenderer,
+			Name:        "by service",
+			HideIfEmpty: true,
+			Options: map[string][]APITopologyOption{"system": {
+				{"show", "System services shown", false, render.FilterNoop},
+				{"hide", "System services hidden", true, render.FilterSystem},
+			}},
+		},
 	)
 }
 
@@ -121,9 +121,10 @@ type APITopologyDesc struct {
 	parent   string
 	renderer render.Renderer
 
-	Name    string                         `json:"name"`
-	Rank    int                            `json:"rank"`
-	Options map[string][]APITopologyOption `json:"options"`
+	Name        string                         `json:"name"`
+	Rank        int                            `json:"rank"`
+	HideIfEmpty bool                           `json:"hide_if_empty"`
+	Options     map[string][]APITopologyOption `json:"options"`
 
 	URL           string            `json:"url"`
 	SubTopologies []APITopologyDesc `json:"sub_topologies,omitempty"`
@@ -241,10 +242,6 @@ func decorateWithStats(rpt report.Report, renderer render.Renderer) topologyStat
 	}
 }
 
-func (r *registry) enableKubernetesTopologies() {
-	r.add(kubernetesTopologies...)
-}
-
 func renderedForRequest(r *http.Request, topology APITopologyDesc) render.Renderer {
 	renderer := topology.renderer
 	for param, opts := range topology.Options {

app/api_topologies_test.go

@@ -27,7 +27,7 @@ func TestAPITopology(t *testing.T) {
 	if err := decoder.Decode(&topologies); err != nil {
 		t.Fatalf("JSON parse error: %s", err)
 	}
-	equals(t, 3, len(topologies))
+	equals(t, 4, len(topologies))
 
 	for _, topology := range topologies {
 		is200(t, ts, topology.URL)
@@ -65,7 +65,7 @@ func TestAPITopologyAddsKubernetes(t *testing.T) {
 	if err := decoder.Decode(&topologies); err != nil {
 		t.Fatalf("JSON parse error: %s", err)
 	}
-	equals(t, 3, len(topologies))
+	equals(t, 4, len(topologies))
 
 	// Enable the kubernetes topologies
 	rpt := report.MakeReport()

app/router.go

@@ -157,9 +157,6 @@ func RegisterReportPostHandler(a Adder, router *mux.Router) {
 			return
 		}
 		a.Add(ctx, rpt)
-		if len(rpt.Pod.Nodes) > 0 {
-			topologyRegistry.enableKubernetesTopologies()
-		}
 		w.WriteHeader(http.StatusOK)
 	}))
 }