Add an example of custom histogram buckets in prometheus

example/prometheus/main.go

@@ -31,18 +31,40 @@ import (
 	"go.opentelemetry.io/otel/attribute"
 	otelprom "go.opentelemetry.io/otel/exporters/prometheus"
 	"go.opentelemetry.io/otel/metric/instrument"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
 	"go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/metric/aggregation"
+	"go.opentelemetry.io/otel/sdk/metric/view"
 )
 
+const meterName = "github.com/open-telemetry/opentelemetry-go/example/prometheus"
+
 func main() {
 	ctx := context.Background()
 
 	// The exporter embeds a default OpenTelemetry Reader and
 	// implements prometheus.Collector, allowing it to be used as
 	// both a Reader and Collector.
 	exporter := otelprom.New()
-	provider := metric.NewMeterProvider(metric.WithReader(exporter))
-	meter := provider.Meter("github.com/open-telemetry/opentelemetry-go/example/prometheus")
+
+	// View to customize histogram
+	customBucketsView, err := view.New(
+		view.MatchInstrumentName("custom_histogram"),
+		view.MatchInstrumentationScope(instrumentation.Scope{Name: meterName}),
+		view.WithSetAggregation(aggregation.ExplicitBucketHistogram{
+			Boundaries: []float64{64, 128, 256, 512, 1024, 2048, 4096},
+		}),
+		view.WithRename("qux"),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Default view to keep all instruments
+	defaultView, err := view.New()
+
+	provider := metric.NewMeterProvider(metric.WithReader(exporter, customBucketsView, defaultView))
+	meter := provider.Meter(meterName)
 
 	// Start the prometheus HTTP server and pass the exporter Collector to it
 	go serveMetrics(exporter.Collector)
@@ -67,14 +89,23 @@ func main() {
 	gauge.Add(ctx, -25, attrs...)
 
 	// This is the equivalent of prometheus.NewHistogramVec
-	histogram, err := meter.SyncFloat64().Histogram("baz", instrument.WithDescription("a very nice histogram"))
+	histogram1, err := meter.SyncFloat64().Histogram("baz", instrument.WithDescription("a very nice histogram"))
+	if err != nil {
+		log.Fatal(err)
+	}
+	histogram1.Record(ctx, 23, attrs...)
+	histogram1.Record(ctx, 7, attrs...)
+	histogram1.Record(ctx, 101, attrs...)
+	histogram1.Record(ctx, 105, attrs...)
+
+	histogram2, err := meter.SyncFloat64().Histogram("custom_histogram", instrument.WithDescription("a histogram with custom buckets and rename"))
 	if err != nil {
 		log.Fatal(err)
 	}
-	histogram.Record(ctx, 23, attrs...)
-	histogram.Record(ctx, 7, attrs...)
-	histogram.Record(ctx, 101, attrs...)
-	histogram.Record(ctx, 105, attrs...)
+	histogram2.Record(ctx, 136, attrs...)
+	histogram2.Record(ctx, 64, attrs...)
+	histogram2.Record(ctx, 701, attrs...)
+	histogram2.Record(ctx, 830, attrs...)
 
 	ctx, _ = signal.NotifyContext(ctx, os.Interrupt)
 	<-ctx.Done()