Chore: Fix issues reported by staticcheck; enable stylecheck linter (#28866)

* Chore: Fix issues reported by staticcheck

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

* Apply suggestions from code review

Co-authored-by: Emil Tullstedt <emil.tullstedt@grafana.com>

pkg/plugins/backendplugin/grpcplugin/client.go

@@ -6,7 +6,6 @@ import (
 	datasourceV1 "github.com/grafana/grafana-plugin-model/go/datasource"
 	rendererV1 "github.com/grafana/grafana-plugin-model/go/renderer"
 	"github.com/grafana/grafana-plugin-sdk-go/backend/grpcplugin"
-	sdkgrpcplugin "github.com/grafana/grafana-plugin-sdk-go/backend/grpcplugin"
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/plugins/backendplugin"
 	"github.com/grafana/grafana/pkg/plugins/backendplugin/pluginextensionv2"
@@ -28,8 +27,8 @@ var handshake = goplugin.HandshakeConfig{
 	ProtocolVersion: DefaultProtocolVersion,
 
 	// The magic cookie values should NEVER be changed.
-	MagicCookieKey:   sdkgrpcplugin.MagicCookieKey,
-	MagicCookieValue: sdkgrpcplugin.MagicCookieValue,
+	MagicCookieKey:   grpcplugin.MagicCookieKey,
+	MagicCookieValue: grpcplugin.MagicCookieValue,
 }
 
 func newClientConfig(executablePath string, env []string, logger log.Logger, versionedPlugins map[int]goplugin.PluginSet) *goplugin.ClientConfig {
@@ -69,10 +68,10 @@ type PluginDescriptor struct {
 // getV2PluginSet returns list of plugins supported on v2.
 func getV2PluginSet() goplugin.PluginSet {
 	return goplugin.PluginSet{
-		"diagnostics": &sdkgrpcplugin.DiagnosticsGRPCPlugin{},
-		"resource":    &sdkgrpcplugin.ResourceGRPCPlugin{},
-		"data":        &sdkgrpcplugin.DataGRPCPlugin{},
-		"transform":   &sdkgrpcplugin.TransformGRPCPlugin{},
+		"diagnostics": &grpcplugin.DiagnosticsGRPCPlugin{},
+		"resource":    &grpcplugin.ResourceGRPCPlugin{},
+		"data":        &grpcplugin.DataGRPCPlugin{},
+		"transform":   &grpcplugin.TransformGRPCPlugin{},
 		"renderer":    &pluginextensionv2.RendererGRPCPlugin{},
 	}
 }
@@ -87,7 +86,7 @@ func NewBackendPlugin(pluginID, executablePath string, startFns PluginStartFuncs
 			DefaultProtocolVersion: {
 				pluginID: &datasourceV1.DatasourcePluginImpl{},
 			},
-			sdkgrpcplugin.ProtocolVersion: getV2PluginSet(),
+			grpcplugin.ProtocolVersion: getV2PluginSet(),
 		},
 		startFns: startFns,
 	})
@@ -103,7 +102,7 @@ func NewRendererPlugin(pluginID, executablePath string, startFns PluginStartFunc
 			DefaultProtocolVersion: {
 				pluginID: &rendererV1.RendererPluginImpl{},
 			},
-			sdkgrpcplugin.ProtocolVersion: getV2PluginSet(),
+			grpcplugin.ProtocolVersion: getV2PluginSet(),
 		},
 		startFns: startFns,
 	})

pkg/plugins/backendplugin/manager.go

@@ -23,11 +23,11 @@ import (
 
 var (
 	// ErrPluginNotRegistered error returned when plugin not registered.
-	ErrPluginNotRegistered = errors.New("Plugin not registered")
+	ErrPluginNotRegistered = errors.New("plugin not registered")
 	// ErrHealthCheckFailed error returned when health check failed.
-	ErrHealthCheckFailed = errors.New("Health check failed")
+	ErrHealthCheckFailed = errors.New("health check failed")
 	// ErrPluginUnavailable error returned when plugin is unavailable.
-	ErrPluginUnavailable = errors.New("Plugin unavailable")
+	ErrPluginUnavailable = errors.New("plugin unavailable")
 	// ErrMethodNotImplemented error returned when plugin method not implemented.
 	ErrMethodNotImplemented = errors.New("method not implemented")
 )
@@ -81,7 +81,7 @@ func (m *manager) Register(pluginID string, factory PluginFactoryFunc) error {
 	defer m.pluginsMu.Unlock()
 
 	if _, exists := m.plugins[pluginID]; exists {
-		return errors.New("Backend plugin already registered")
+		return fmt.Errorf("backend plugin %s already registered", pluginID)
 	}
 
 	pluginSettings := pluginSettings{}
@@ -141,7 +141,7 @@ func (m *manager) StartPlugin(ctx context.Context, pluginID string) error {
 	}
 
 	if p.IsManaged() {
-		return errors.New("Backend plugin is managed and cannot be manually started")
+		return errors.New("backend plugin is managed and cannot be manually started")
 	}
 
 	return startPluginAndRestartKilledProcesses(ctx, p)
@@ -241,7 +241,7 @@ func (m *manager) callResourceInternal(w http.ResponseWriter, req *http.Request,
 
 	body, err := ioutil.ReadAll(req.Body)
 	if err != nil {
-		return errors.New("Failed to read request body")
+		return fmt.Errorf("failed to read request body: %w", err)
 	}
 
 	crReq := &backend.CallResourceRequest{
@@ -315,13 +315,13 @@ func flushStream(plugin Plugin, stream CallResourceClientResponseStream, w http.
 		resp, err := stream.Recv()
 		if err == io.EOF {
 			if processedStreams == 0 {
-				return errors.New("Received empty resource response")
+				return errors.New("received empty resource response")
 			}
 			return nil
 		}
 		if err != nil {
 			if processedStreams == 0 {
-				return errutil.Wrap("Failed to receive response from resource call", err)
+				return errutil.Wrap("failed to receive response from resource call", err)
 			}
 
 			plugin.Logger().Error("Failed to receive response from resource call", "error", err)

pkg/plugins/backendplugin/resource_response_stream.go

@@ -23,7 +23,7 @@ type callResourceResponseStream struct {
 
 func (s *callResourceResponseStream) Send(res *backend.CallResourceResponse) error {
 	if s.closed {
-		return errors.New("Cannot send to a closed stream")
+		return errors.New("cannot send to a closed stream")
 	}
 
 	select {
@@ -48,7 +48,7 @@ func (s *callResourceResponseStream) Recv() (*backend.CallResourceResponse, erro
 
 func (s *callResourceResponseStream) Close() error {
 	if s.closed {
-		return errors.New("Cannot close a closed stream")
+		return errors.New("cannot close a closed stream")
 	}
 
 	close(s.stream)