Enable admin users API on gateway (#6659)

This is only enabled when etcd is enabled, healing is only
enabled for erasure coded backend.

cmd/admin-router.go

@@ -53,12 +53,14 @@ func registerAdminRouter(router *mux.Router) {
 	// Info operations
 	adminV1Router.Methods(http.MethodGet).Path("/info").HandlerFunc(httpTraceAll(adminAPI.ServerInfoHandler))
 
-	/// Heal operations
+	if globalIsDistXL || globalIsXL {
+		/// Heal operations
 
-	// Heal processing endpoint.
-	adminV1Router.Methods(http.MethodPost).Path("/heal/").HandlerFunc(httpTraceAll(adminAPI.HealHandler))
-	adminV1Router.Methods(http.MethodPost).Path("/heal/{bucket}").HandlerFunc(httpTraceAll(adminAPI.HealHandler))
-	adminV1Router.Methods(http.MethodPost).Path("/heal/{bucket}/{prefix:.*}").HandlerFunc(httpTraceAll(adminAPI.HealHandler))
+		// Heal processing endpoint.
+		adminV1Router.Methods(http.MethodPost).Path("/heal/").HandlerFunc(httpTraceAll(adminAPI.HealHandler))
+		adminV1Router.Methods(http.MethodPost).Path("/heal/{bucket}").HandlerFunc(httpTraceAll(adminAPI.HealHandler))
+		adminV1Router.Methods(http.MethodPost).Path("/heal/{bucket}/{prefix:.*}").HandlerFunc(httpTraceAll(adminAPI.HealHandler))
+	}
 
 	// Profiling operations
 	adminV1Router.Methods(http.MethodPost).Path("/profiling/start").HandlerFunc(httpTraceAll(adminAPI.StartProfilingHandler)).
@@ -102,4 +104,7 @@ func registerAdminRouter(router *mux.Router) {
 
 	// List policies
 	adminV1Router.Methods(http.MethodGet).Path("/list-canned-policies").HandlerFunc(httpTraceHdrs(adminAPI.ListCannedPolicies))
+
+	// If none of the routes match.
+	adminV1Router.NotFoundHandler = http.HandlerFunc(httpTraceHdrs(notFoundHandler))
 }

cmd/gateway-main.go

@@ -169,6 +169,14 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 
 	router := mux.NewRouter().SkipClean(true)
 
+	if globalEtcdClient != nil {
+		// Enable STS router if etcd is enabled.
+		registerSTSRouter(router)
+
+		// Enable admin router if etcd is enabled.
+		registerAdminRouter(router)
+	}
+
 	// Add healthcheck router
 	registerHealthCheckRouter(router)
 
@@ -180,11 +188,6 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 		logger.FatalIf(registerWebRouter(router), "Unable to configure web browser")
 	}
 
-	// Enable STS router if etcd is enabled.
-	if globalEtcdClient != nil {
-		registerSTSRouter(router)
-	}
-
 	// Add API router.
 	registerAPIRouter(router)