Add plugin's support for provider

Co-authored-by: Julien Salleyron <julien@traefik.io>

pkg/api/handler_overview.go

@@ -212,6 +212,10 @@ func getProviders(conf static.Configuration) []string {
 			if !field.IsNil() {
 				providers = append(providers, v.Type().Field(i).Name)
 			}
+		} else if field.Kind() == reflect.Map && field.Type().Elem() == reflect.TypeOf(static.PluginConf{}) {
+			for _, value := range field.MapKeys() {
+				providers = append(providers, "plugin-"+value.String())
+			}
 		}
 	}
 

pkg/api/handler_overview_test.go

@@ -217,6 +217,9 @@ func TestHandler_Overview(t *testing.T) {
 					KubernetesCRD:     &crd.Provider{},
 					Rest:              &rest.Provider{},
 					Rancher:           &rancher.Provider{},
+					Plugin: map[string]static.PluginConf{
+						"test": map[string]interface{}{},
+					},
 				},
 			},
 			confDyn: runtime.Configuration{},

pkg/api/testdata/overview-providers.json

@@ -28,7 +28,8 @@
 		"KubernetesIngress",
 		"KubernetesCRD",
 		"Rest",
-		"Rancher"
+		"Rancher",
+		"plugin-test"
 	],
 	"tcp": {
 		"routers": {