Allow Stackdriver users to pass monitoring and tracing options separately (#699)

Fixes #691.

Author: rakyll

exporter/stackdriver/stackdriver.go

@@ -49,10 +49,15 @@ type Options struct {
 	// Optional.
 	OnError func(err error)
 
-	// ClientOptions are additional options to be passed
+	// MonitoringClientOptions are additional options to be passed
 	// to the underlying Stackdriver Monitoring API client.
 	// Optional.
-	ClientOptions []option.ClientOption
+	MonitoringClientOptions []option.ClientOption
+
+	// TraceClientOptions are additional options to be passed
+	// to the underlying Stackdriver Trace API client.
+	// Optional.
+	TraceClientOptions []option.ClientOption
 
 	// BundleDelayThreshold determines the max amount of time
 	// the exporter can wait before uploading view data to

exporter/stackdriver/stats.go

@@ -90,7 +90,7 @@ func newStatsExporter(o Options) (*statsExporter, error) {
 
 	seenProjects[o.ProjectID] = true
 
-	opts := append(o.ClientOptions, option.WithUserAgent(internal.UserAgent))
+	opts := append(o.MonitoringClientOptions, option.WithUserAgent(internal.UserAgent))
 	client, err := monitoring.NewMetricClient(context.Background(), opts...)
 	if err != nil {
 		return nil, err

exporter/stackdriver/stats_test.go

@@ -39,7 +39,7 @@ var authOptions = []option.ClientOption{option.WithGRPCConn(&grpc.ClientConn{})}
 func TestRejectBlankProjectID(t *testing.T) {
 	ids := []string{"", "     ", " "}
 	for _, projectID := range ids {
-		opts := Options{ProjectID: projectID, ClientOptions: authOptions}
+		opts := Options{ProjectID: projectID, MonitoringClientOptions: authOptions}
 		exp, err := newStatsExporter(opts)
 		if err == nil || exp != nil {
 			t.Errorf("%q ProjectID must be rejected: NewExporter() = %v err = %q", projectID, exp, err)
@@ -52,7 +52,7 @@ func TestRejectBlankProjectID(t *testing.T) {
 func TestNewExporterSingletonPerProcess(t *testing.T) {
 	ids := []string{"open-census.io", "x", "fakeProjectID"}
 	for _, projectID := range ids {
-		opts := Options{ProjectID: projectID, ClientOptions: authOptions}
+		opts := Options{ProjectID: projectID, MonitoringClientOptions: authOptions}
 		exp, err := newStatsExporter(opts)
 		if err != nil {
 			t.Errorf("NewExporter() projectID = %q err = %q", projectID, err)

exporter/stackdriver/trace.go

@@ -42,7 +42,7 @@ type traceExporter struct {
 var _ trace.Exporter = (*traceExporter)(nil)
 
 func newTraceExporter(o Options) (*traceExporter, error) {
-	client, err := tracingclient.NewClient(context.Background(), o.ClientOptions...)
+	client, err := tracingclient.NewClient(context.Background(), o.TraceClientOptions...)
 	if err != nil {
 		return nil, fmt.Errorf("stackdriver: couldn't initialize trace client: %v", err)
 	}