Fix: fix loading symbolically linked plugins (#35635) (#35693)

(cherry picked from commit 5b5cb94809)

Co-authored-by: Domas <domas.lapinskas@grafana.com>

pkg/plugins/manager/manager_test.go

@@ -399,6 +399,24 @@ func TestPluginManager_Init(t *testing.T) {
 		assert.Equal(t, "Grafana Labs", p.SignatureOrg)
 		assert.False(t, p.IsCorePlugin)
 	})
+
+	t.Run("With back-end plugin that is symlinked to plugins dir", func(t *testing.T) {
+		origAppURL := setting.AppUrl
+		t.Cleanup(func() {
+			setting.AppUrl = origAppURL
+		})
+		setting.AppUrl = defaultAppURL
+
+		pm := createManager(t, func(pm *PluginManager) {
+			pm.Cfg.PluginsPath = "testdata/symbolic-plugin-dirs"
+		})
+		err := pm.Init()
+		require.NoError(t, err)
+		// This plugin should be properly registered, even though it is symlinked to prlugins dir
+		require.Empty(t, pm.scanningErrors)
+		const pluginID = "test"
+		assert.NotNil(t, pm.plugins[pluginID])
+	})
 }
 
 func TestPluginManager_IsBackendOnlyPlugin(t *testing.T) {

pkg/plugins/manager/testdata/symbolic-plugin-dirs/plugin

@@ -0,0 +1 @@
+../symbolic-file-links/plugin

pkg/util/filepath.go

@@ -55,28 +55,35 @@ func walk(path string, info os.FileInfo, resolvedPath string, symlinkPathsFollow
 		}
 		return err
 	}
-	// We only want to lstat on directories. If this entry is a symbolic link to a file, no need to recurse.
-	if info.IsDir() {
-		if resolvedPath != "" && info.Mode()&os.ModeSymlink == os.ModeSymlink {
-			path2, err := os.Readlink(resolvedPath)
-			if err != nil {
-				return err
-			}
-			// vout("SymLink Path: %v, links to: %v", resolvedPath, path2)
-			if symlinkPathsFollowed != nil {
-				if _, ok := symlinkPathsFollowed[path2]; ok {
-					errMsg := "potential symLink infinite loop, path: %v, link to: %v"
-					return fmt.Errorf(errMsg, resolvedPath, path2)
-				}
-				symlinkPathsFollowed[path2] = true
-			}
-			info2, err := os.Lstat(path2)
-			if err != nil {
-				return err
-			}
-			return walk(path, info2, path2, symlinkPathsFollowed, walkFn)
+
+	if resolvedPath != "" && info.Mode()&os.ModeSymlink == os.ModeSymlink {
+		// We only want to lstat on directories. If this entry is a symbolic link to a file, no need to recurse.
+		statInfo, err := os.Stat(resolvedPath)
+		if err != nil {
+			return err
+		}
+		if !statInfo.IsDir() {
+			return nil
 		}
 
+		path2, err := filepath.EvalSymlinks(resolvedPath)
+		if err != nil {
+			return err
+		}
+		// vout("SymLink Path: %v, links to: %v", resolvedPath, path2)
+		if symlinkPathsFollowed != nil {
+			if _, ok := symlinkPathsFollowed[path2]; ok {
+				errMsg := "potential symLink infinite loop, path: %v, link to: %v"
+				return fmt.Errorf(errMsg, resolvedPath, path2)
+			}
+			symlinkPathsFollowed[path2] = true
+		}
+		info2, err := os.Lstat(path2)
+		if err != nil {
+			return err
+		}
+		return walk(path, info2, path2, symlinkPathsFollowed, walkFn)
+	} else if info.IsDir() {
 		list, err := ioutil.ReadDir(path)
 		if err != nil {
 			return walkFn(resolvedPath, info, err)