Plugins: Update renderer plugin source (#80643)

* rework renderer plugin source

* add tests

pkg/plugins/manager/loader/loader.go

@@ -75,6 +75,10 @@ func (l *Loader) instrumentLoad(ctx context.Context, src plugins.PluginSource) f
 
 	return func(logger log.Logger, start time.Time) func([]*plugins.Plugin) {
 		return func(plugins []*plugins.Plugin) {
+			if len(plugins) == 0 {
+				logger.Debug("Plugin source loaded, though no plugins were found")
+				return
+			}
 			names := make([]string, len(plugins))
 			for i, p := range plugins {
 				names[i] = p.ID

pkg/plugins/manager/sources/source_local_disk.go

@@ -2,6 +2,10 @@ package sources
 
 import (
 	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"slices"
 
 	"github.com/grafana/grafana/pkg/plugins"
 )
@@ -36,3 +40,31 @@ func (s *LocalSource) DefaultSignature(_ context.Context) (plugins.Signature, bo
 		return plugins.Signature{}, false
 	}
 }
+
+func DirAsLocalSources(pluginsPath string, class plugins.Class) ([]*LocalSource, error) {
+	if pluginsPath == "" {
+		return []*LocalSource{}, errors.New("plugins path not configured")
+	}
+
+	// It's safe to ignore gosec warning G304 since the variable part of the file path comes from a configuration
+	// variable.
+	// nolint:gosec
+	d, err := os.ReadDir(pluginsPath)
+	if err != nil {
+		return []*LocalSource{}, errors.New("failed to open plugins path")
+	}
+
+	var pluginDirs []string
+	for _, dir := range d {
+		if dir.IsDir() || dir.Type()&os.ModeSymlink == os.ModeSymlink {
+			pluginDirs = append(pluginDirs, filepath.Join(pluginsPath, dir.Name()))
+		}
+	}
+	slices.Sort(pluginDirs)
+
+	var sources []*LocalSource
+	for _, dir := range pluginDirs {
+		sources = append(sources, NewLocalSource(class, []string{dir}))
+	}
+	return sources, nil
+}

pkg/plugins/manager/sources/source_local_disk_test.go

@@ -0,0 +1,71 @@
+package sources
+
+import (
+	"errors"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/grafana/grafana/pkg/plugins"
+)
+
+func TestDirAsLocalSources(t *testing.T) {
+	testdataDir := "../testdata"
+
+	tests := []struct {
+		name        string
+		pluginsPath string
+		expected    []*LocalSource
+		err         error
+	}{
+		{
+			name:        "Empty path returns an error",
+			pluginsPath: "",
+			expected:    []*LocalSource{},
+			err:         errors.New("plugins path not configured"),
+		},
+		{
+			name:        "Directory with subdirectories",
+			pluginsPath: filepath.Join(testdataDir, "pluginRootWithDist"),
+			expected: []*LocalSource{
+				{
+					paths: []string{filepath.Join(testdataDir, "pluginRootWithDist", "datasource")},
+					class: plugins.ClassExternal,
+				},
+				{
+					paths: []string{filepath.Join(testdataDir, "pluginRootWithDist", "dist")},
+					class: plugins.ClassExternal,
+				},
+				{
+					paths: []string{filepath.Join(testdataDir, "pluginRootWithDist", "panel")},
+					class: plugins.ClassExternal,
+				},
+			},
+		},
+		{
+			name:        "Directory with no subdirectories",
+			pluginsPath: filepath.Join(testdataDir, "pluginRootWithDist", "datasource"),
+			expected:    nil,
+		},
+		{
+			name:        "Directory with a symlink to a directory",
+			pluginsPath: filepath.Join(testdataDir, "symbolic-plugin-dirs"),
+			expected: []*LocalSource{
+				{
+					paths: []string{filepath.Join(testdataDir, "symbolic-plugin-dirs", "plugin")},
+					class: plugins.ClassExternal,
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := DirAsLocalSources(tt.pluginsPath, plugins.ClassExternal)
+			if tt.err != nil {
+				require.Errorf(t, err, tt.err.Error())
+			}
+			require.Equal(t, tt.expected, got)
+		})
+	}
+}

pkg/plugins/manager/sources/sources.go

@@ -2,9 +2,7 @@ package sources
 
 import (
 	"context"
-	"os"
 	"path/filepath"
-	"slices"
 
 	"github.com/grafana/grafana/pkg/plugins"
 	"github.com/grafana/grafana/pkg/plugins/log"
@@ -34,33 +32,17 @@ func (s *Service) List(_ context.Context) []plugins.PluginSource {
 }
 
 func (s *Service) externalPluginSources() []plugins.PluginSource {
-	var sources []plugins.PluginSource
-	if s.cfg.PluginsPath == "" {
-		return sources
-	}
-
-	pluginsPath := s.cfg.PluginsPath
-	// It's safe to ignore gosec warning G304 since the variable part of the file path comes from a configuration
-	// variable.
-	// nolint:gosec
-	d, err := os.ReadDir(pluginsPath)
+	localSrcs, err := DirAsLocalSources(s.cfg.PluginsPath, plugins.ClassExternal)
 	if err != nil {
-		s.log.Error("Failed to open plugins path", "path", pluginsPath, "error", err)
-		return sources
+		s.log.Error("Failed to load external plugins", "error", err)
+		return []plugins.PluginSource{}
 	}
 
-	var pluginDirs []string
-	for _, dir := range d {
-		if dir.IsDir() || dir.Type()&os.ModeSymlink == os.ModeSymlink {
-			pluginDirs = append(pluginDirs, filepath.Join(pluginsPath, dir.Name()))
-		}
+	var srcs []plugins.PluginSource
+	for _, src := range localSrcs {
+		srcs = append(srcs, src)
 	}
-	slices.Sort(pluginDirs)
-
-	for _, dir := range pluginDirs {
-		sources = append(sources, NewLocalSource(plugins.ClassExternal, []string{dir}))
-	}
-	return sources
+	return srcs
 }
 
 func (s *Service) pluginSettingSources() []plugins.PluginSource {