Allow overriding the DisplayName prefix in stackdriver metric descrip…

…tors (#583)

Closes #582

exporter/stackdriver/stackdriver.go

@@ -71,6 +71,10 @@ type Options struct {
 	// with type global and no resource labels will be used.
 	// Optional.
 	Resource *monitoredrespb.MonitoredResource
+
+	// MetricPrefix overrides the OpenCensus prefix of a stackdriver metric.
+	// Optional.
+	MetricPrefix string
 }
 
 // Exporter is a stats.Exporter and trace.Exporter

exporter/stackdriver/stats.go

@@ -50,6 +50,7 @@ import (
 const maxTimeSeriesPerUpload = 200
 const opencensusTaskKey = "opencensus_task"
 const opencensusTaskDescription = "Opencensus task identifier"
+const defaultDisplayNamePrefix = "OpenCensus"
 
 // statsExporter exports stats to the Stackdriver Monitoring.
 type statsExporter struct {
@@ -278,11 +279,15 @@ func (e *statsExporter) createMeasure(ctx context.Context, vd *view.Data) error
 	}
 
 	metricKind = metricpb.MetricDescriptor_CUMULATIVE
+	displayNamePrefix := defaultDisplayNamePrefix
+	if e.o.MetricPrefix != "" {
+		displayNamePrefix = e.o.MetricPrefix
+	}
 
 	md, err = createMetricDescriptor(ctx, e.c, &monitoringpb.CreateMetricDescriptorRequest{
 		Name: monitoring.MetricProjectPath(e.o.ProjectID),
 		MetricDescriptor: &metricpb.MetricDescriptor{
-			DisplayName: path.Join("OpenCensus", viewName),
+			DisplayName: path.Join(displayNamePrefix, viewName),
 			Description: m.Description(),
 			Unit:        m.Unit(),
 			Type:        namespacedViewName(viewName, false),