Enable Lint Rules: struct-tag & unexported-return (jaegertracing#5533)

## Which problem is this PR solving?
-  Partial Fix for jaegertracing#5506

## Description of the changes
- Enabled struct-tag & unexported-return in revive linter
- Only use tags on exported fields
- Converted exported function to have an exported return type

## How was this change tested?
- `make lint` `make test`

## Checklist
- [x] I have read
https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
- [x] I have signed all commits
- [ ] I have added unit tests for the new functionality
- [x] I have run lint and test steps successfully
  - for `jaeger`: `make lint test`
  - for `jaeger-ui`: `yarn lint` and `yarn test`
  -

---------

Signed-off-by: FlamingSaint <[email protected]>

.golangci.yml

@@ -207,9 +207,6 @@ linters-settings:
         # investigate, could be real bugs. But didn't recent Go version changed loop variables semantics?
         - name: range-val-address
           disabled: true
-        # enable after cleanup: "tag on not-exported field"
-        - name: struct-tag
-          disabled: true
         # this is idiocy, promotes less readable code. Don't enable.
         - name: var-declaration
           disabled: true
@@ -219,9 +216,6 @@ linters-settings:
         # "no nested structs are allowed" - don't enable, doesn't make sense
         - name: nested-structs
           disabled: true
-        # enable after cleanup
-        - name: unexported-return
-          disabled: true
         # looks useful, but requires refactoring: "calls to log.Fatal only in main() or init() functions"
         - name: deep-exit
           disabled: true

pkg/config/tlscfg/options.go

@@ -40,7 +40,7 @@ type Options struct {
 	MaxVersion     string        `mapstructure:"max_version"`
 	SkipHostVerify bool          `mapstructure:"skip_host_verify"`
 	ReloadInterval time.Duration `mapstructure:"reload_interval"`
-	certWatcher    *certWatcher  `mapstructure:"-"`
+	certWatcher    *certWatcher
 }
 
 var systemCertPool = x509.SystemCertPool // to allow overriding in unit test

plugin/storage/grpc/shared/grpc_client.go

@@ -38,16 +38,16 @@ import (
 const BearerTokenKey = "bearer.token"
 
 var (
-	_ StoragePlugin        = (*grpcClient)(nil)
-	_ ArchiveStoragePlugin = (*grpcClient)(nil)
-	_ PluginCapabilities   = (*grpcClient)(nil)
+	_ StoragePlugin        = (*GRPCClient)(nil)
+	_ ArchiveStoragePlugin = (*GRPCClient)(nil)
+	_ PluginCapabilities   = (*GRPCClient)(nil)
 
 	// upgradeContext composites several steps of upgrading context
 	upgradeContext = composeContextUpgradeFuncs(upgradeContextWithBearerToken)
 )
 
-// grpcClient implements shared.StoragePlugin and reads/writes spans and dependencies
-type grpcClient struct {
+// GRPCClient implements shared.StoragePlugin and reads/writes spans and dependencies
+type GRPCClient struct {
 	readerClient        storage_v1.SpanReaderPluginClient
 	writerClient        storage_v1.SpanWriterPluginClient
 	archiveReaderClient storage_v1.ArchiveSpanReaderPluginClient
@@ -57,8 +57,8 @@ type grpcClient struct {
 	streamWriterClient  storage_v1.StreamingSpanWriterPluginClient
 }
 
-func NewGRPCClient(c *grpc.ClientConn) *grpcClient {
-	return &grpcClient{
+func NewGRPCClient(c *grpc.ClientConn) *GRPCClient {
+	return &GRPCClient{
 		readerClient:        storage_v1.NewSpanReaderPluginClient(c),
 		writerClient:        storage_v1.NewSpanWriterPluginClient(c),
 		archiveReaderClient: storage_v1.NewArchiveSpanReaderPluginClient(c),
@@ -100,34 +100,34 @@ func upgradeContextWithBearerToken(ctx context.Context) context.Context {
 }
 
 // DependencyReader implements shared.StoragePlugin.
-func (c *grpcClient) DependencyReader() dependencystore.Reader {
+func (c *GRPCClient) DependencyReader() dependencystore.Reader {
 	return c
 }
 
 // SpanReader implements shared.StoragePlugin.
-func (c *grpcClient) SpanReader() spanstore.Reader {
+func (c *GRPCClient) SpanReader() spanstore.Reader {
 	return c
 }
 
 // SpanWriter implements shared.StoragePlugin.
-func (c *grpcClient) SpanWriter() spanstore.Writer {
+func (c *GRPCClient) SpanWriter() spanstore.Writer {
 	return c
 }
 
-func (c *grpcClient) StreamingSpanWriter() spanstore.Writer {
+func (c *GRPCClient) StreamingSpanWriter() spanstore.Writer {
 	return newStreamingSpanWriter(c.streamWriterClient)
 }
 
-func (c *grpcClient) ArchiveSpanReader() spanstore.Reader {
+func (c *GRPCClient) ArchiveSpanReader() spanstore.Reader {
 	return &archiveReader{client: c.archiveReaderClient}
 }
 
-func (c *grpcClient) ArchiveSpanWriter() spanstore.Writer {
+func (c *GRPCClient) ArchiveSpanWriter() spanstore.Writer {
 	return &archiveWriter{client: c.archiveWriterClient}
 }
 
 // GetTrace takes a traceID and returns a Trace associated with that traceID
-func (c *grpcClient) GetTrace(ctx context.Context, traceID model.TraceID) (*model.Trace, error) {
+func (c *GRPCClient) GetTrace(ctx context.Context, traceID model.TraceID) (*model.Trace, error) {
 	stream, err := c.readerClient.GetTrace(upgradeContext(ctx), &storage_v1.GetTraceRequest{
 		TraceID: traceID,
 	})
@@ -142,7 +142,7 @@ func (c *grpcClient) GetTrace(ctx context.Context, traceID model.TraceID) (*mode
 }
 
 // GetServices returns a list of all known services
-func (c *grpcClient) GetServices(ctx context.Context) ([]string, error) {
+func (c *GRPCClient) GetServices(ctx context.Context) ([]string, error) {
 	resp, err := c.readerClient.GetServices(upgradeContext(ctx), &storage_v1.GetServicesRequest{})
 	if err != nil {
 		return nil, fmt.Errorf("plugin error: %w", err)
@@ -152,7 +152,7 @@ func (c *grpcClient) GetServices(ctx context.Context) ([]string, error) {
 }
 
 // GetOperations returns the operations of a given service
-func (c *grpcClient) GetOperations(
+func (c *GRPCClient) GetOperations(
 	ctx context.Context,
 	query spanstore.OperationQueryParameters,
 ) ([]spanstore.Operation, error) {
@@ -183,7 +183,7 @@ func (c *grpcClient) GetOperations(
 }
 
 // FindTraces retrieves traces that match the traceQuery
-func (c *grpcClient) FindTraces(ctx context.Context, query *spanstore.TraceQueryParameters) ([]*model.Trace, error) {
+func (c *GRPCClient) FindTraces(ctx context.Context, query *spanstore.TraceQueryParameters) ([]*model.Trace, error) {
 	stream, err := c.readerClient.FindTraces(upgradeContext(ctx), &storage_v1.FindTracesRequest{
 		Query: &storage_v1.TraceQueryParameters{
 			ServiceName:   query.ServiceName,
@@ -221,7 +221,7 @@ func (c *grpcClient) FindTraces(ctx context.Context, query *spanstore.TraceQuery
 }
 
 // FindTraceIDs retrieves traceIDs that match the traceQuery
-func (c *grpcClient) FindTraceIDs(ctx context.Context, query *spanstore.TraceQueryParameters) ([]model.TraceID, error) {
+func (c *GRPCClient) FindTraceIDs(ctx context.Context, query *spanstore.TraceQueryParameters) ([]model.TraceID, error) {
 	resp, err := c.readerClient.FindTraceIDs(upgradeContext(ctx), &storage_v1.FindTraceIDsRequest{
 		Query: &storage_v1.TraceQueryParameters{
 			ServiceName:   query.ServiceName,
@@ -242,7 +242,7 @@ func (c *grpcClient) FindTraceIDs(ctx context.Context, query *spanstore.TraceQue
 }
 
 // WriteSpan saves the span
-func (c *grpcClient) WriteSpan(ctx context.Context, span *model.Span) error {
+func (c *GRPCClient) WriteSpan(ctx context.Context, span *model.Span) error {
 	_, err := c.writerClient.WriteSpan(ctx, &storage_v1.WriteSpanRequest{
 		Span: span,
 	})
@@ -253,7 +253,7 @@ func (c *grpcClient) WriteSpan(ctx context.Context, span *model.Span) error {
 	return nil
 }
 
-func (c *grpcClient) Close() error {
+func (c *GRPCClient) Close() error {
 	_, err := c.writerClient.Close(context.Background(), &storage_v1.CloseWriterRequest{})
 	if err != nil && status.Code(err) != codes.Unimplemented {
 		return fmt.Errorf("plugin error: %w", err)
@@ -263,7 +263,7 @@ func (c *grpcClient) Close() error {
 }
 
 // GetDependencies returns all interservice dependencies
-func (c *grpcClient) GetDependencies(ctx context.Context, endTs time.Time, lookback time.Duration) ([]model.DependencyLink, error) {
+func (c *GRPCClient) GetDependencies(ctx context.Context, endTs time.Time, lookback time.Duration) ([]model.DependencyLink, error) {
 	resp, err := c.depsReaderClient.GetDependencies(ctx, &storage_v1.GetDependenciesRequest{
 		EndTime:   endTs,
 		StartTime: endTs.Add(-lookback),
@@ -275,7 +275,7 @@ func (c *grpcClient) GetDependencies(ctx context.Context, endTs time.Time, lookb
 	return resp.Dependencies, nil
 }
 
-func (c *grpcClient) Capabilities() (*Capabilities, error) {
+func (c *GRPCClient) Capabilities() (*Capabilities, error) {
 	capabilities, err := c.capabilitiesClient.Capabilities(context.Background(), &storage_v1.CapabilitiesRequest{})
 	if status.Code(err) == codes.Unimplemented {
 		return &Capabilities{}, nil

plugin/storage/grpc/shared/grpc_client_test.go

@@ -73,7 +73,7 @@ var (
 )
 
 type grpcClientTest struct {
-	client        *grpcClient
+	client        *GRPCClient
 	spanReader    *grpcMocks.SpanReaderPluginClient
 	spanWriter    *grpcMocks.SpanWriterPluginClient
 	archiveReader *grpcMocks.ArchiveSpanReaderPluginClient
@@ -93,7 +93,7 @@ func withGRPCClient(fn func(r *grpcClientTest)) {
 	capabilities := new(grpcMocks.PluginCapabilitiesClient)
 
 	r := &grpcClientTest{
-		client: &grpcClient{
+		client: &GRPCClient{
 			readerClient:        spanReader,
 			writerClient:        spanWriter,
 			archiveReaderClient: archiveReader,