Plugins: Only load transform plug-ins if expressions feature on (#24110)

* PluginManager: Only load transform plugins if expressions feature on

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

pkg/plugins/plugins.go

@@ -241,7 +241,7 @@ func (scanner *PluginScanner) walker(currentPath string, f os.FileInfo, err erro
 	}
 
 	if f.Name() == "plugin.json" {
-		err := scanner.loadPluginJson(currentPath)
+		err := scanner.loadPlugin(currentPath)
 		if err != nil {
 			scanner.log.Error("Failed to load plugin", "error", err, "pluginPath", filepath.Dir(currentPath))
 			scanner.errors = append(scanner.errors, err)
@@ -250,7 +250,7 @@ func (scanner *PluginScanner) walker(currentPath string, f os.FileInfo, err erro
 	return nil
 }
 
-func (scanner *PluginScanner) loadPluginJson(pluginJsonFilePath string) error {
+func (scanner *PluginScanner) loadPlugin(pluginJsonFilePath string) error {
 	currentDir := filepath.Dir(pluginJsonFilePath)
 	reader, err := os.Open(pluginJsonFilePath)
 	if err != nil {
@@ -269,6 +269,16 @@ func (scanner *PluginScanner) loadPluginJson(pluginJsonFilePath string) error {
 		return errors.New("did not find type or id properties in plugin.json")
 	}
 
+	// The expressions feature toggle corresponds to transform plug-ins.
+	if pluginCommon.Type == "transform" {
+		isEnabled := scanner.cfg.IsExpressionsEnabled()
+		if !isEnabled {
+			scanner.log.Debug("Transform plugin is disabled since the expressions feature toggle is not enabled",
+				"pluginID", pluginCommon.Id)
+			return nil
+		}
+	}
+
 	pluginCommon.PluginDir = filepath.Dir(pluginJsonFilePath)
 
 	// For the time being, we choose to only require back-end plugins to be signed

pkg/plugins/plugins_test.go

@@ -77,7 +77,7 @@ func TestPluginManager_Init(t *testing.T) {
 			Cfg: &setting.Cfg{
 				PluginsAllowUnsigned: []string{"test"},
 			},
-			BackendPluginManager: fakeBackendPluginManager{},
+			BackendPluginManager: &fakeBackendPluginManager{},
 		}
 		err := pm.Init()
 		require.NoError(t, err)
@@ -100,6 +100,46 @@ func TestPluginManager_Init(t *testing.T) {
 
 		assert.Equal(t, []error{fmt.Errorf(`plugin "test" has an invalid signature`)}, pm.scanningErrors)
 	})
+
+	t.Run("Transform plugins should be ignored when expressions feature is off", func(t *testing.T) {
+		origPluginsPath := setting.PluginsPath
+		t.Cleanup(func() {
+			setting.PluginsPath = origPluginsPath
+		})
+		setting.PluginsPath = "testdata/behind-feature-flag"
+
+		fm := fakeBackendPluginManager{}
+		pm := &PluginManager{
+			Cfg:                  &setting.Cfg{},
+			BackendPluginManager: &fm,
+		}
+		err := pm.Init()
+		require.NoError(t, err)
+
+		assert.Empty(t, pm.scanningErrors)
+		assert.Equal(t, 0, fm.registerCount)
+	})
+
+	t.Run("Transform plugins should be loaded when expressions feature is on", func(t *testing.T) {
+		origPluginsPath := setting.PluginsPath
+		t.Cleanup(func() {
+			setting.PluginsPath = origPluginsPath
+		})
+		setting.PluginsPath = "testdata/behind-feature-flag"
+
+		pm := &PluginManager{
+			Cfg: &setting.Cfg{
+				FeatureToggles: map[string]bool{
+					"expressions": true,
+				},
+			},
+			BackendPluginManager: &fakeBackendPluginManager{},
+		}
+		err := pm.Init()
+		require.NoError(t, err)
+
+		assert.Equal(t, []error{fmt.Errorf(`plugin "gel" is unsigned`)}, pm.scanningErrors)
+	})
 }
 
 func TestPluginManager_IsBackendOnlyPlugin(t *testing.T) {
@@ -123,23 +163,25 @@ func TestPluginManager_IsBackendOnlyPlugin(t *testing.T) {
 }
 
 type fakeBackendPluginManager struct {
+	registerCount int
 }
 
-func (f fakeBackendPluginManager) Register(descriptor backendplugin.PluginDescriptor) error {
+func (f *fakeBackendPluginManager) Register(descriptor backendplugin.PluginDescriptor) error {
+	f.registerCount++
 	return nil
 }
 
-func (f fakeBackendPluginManager) StartPlugin(ctx context.Context, pluginID string) error {
+func (f *fakeBackendPluginManager) StartPlugin(ctx context.Context, pluginID string) error {
 	return nil
 }
 
-func (f fakeBackendPluginManager) CollectMetrics(ctx context.Context, pluginID string) (*backendplugin.CollectMetricsResult, error) {
+func (f *fakeBackendPluginManager) CollectMetrics(ctx context.Context, pluginID string) (*backendplugin.CollectMetricsResult, error) {
 	return nil, nil
 }
 
-func (f fakeBackendPluginManager) CheckHealth(ctx context.Context, pCtx backend.PluginContext) (*backendplugin.CheckHealthResult, error) {
+func (f *fakeBackendPluginManager) CheckHealth(ctx context.Context, pCtx backend.PluginContext) (*backendplugin.CheckHealthResult, error) {
 	return nil, nil
 }
 
-func (f fakeBackendPluginManager) CallResource(pluginConfig backend.PluginContext, ctx *models.ReqContext, path string) {
+func (f *fakeBackendPluginManager) CallResource(pluginConfig backend.PluginContext, ctx *models.ReqContext, path string) {
 }

pkg/plugins/testdata/behind-feature-flag/gel/plugin.json

@@ -0,0 +1,13 @@
+{
+  "type": "transform",
+  "name": "GEL",
+  "id": "gel",
+  "backend": true,
+  "info": {
+    "description": "Test",
+    "author": {
+      "name": "Grafana Labs",
+      "url": "https://grafana.com"
+    }
+  }
+}

pkg/setting/setting.go

@@ -289,6 +289,11 @@ type Cfg struct {
 	FeatureToggles map[string]bool
 }
 
+// IsExpressionsEnabled returns whether the expressions feature is enabled.
+func (c Cfg) IsExpressionsEnabled() bool {
+	return c.FeatureToggles["expressions"]
+}
+
 type CommandLineArgs struct {
 	Config   string
 	HomePath string