Move view example into prometheus example, and deprecate /example/view (#4649)

* move view example into prometheus example, and deprecate /example/view

* fix lint

---------

Co-authored-by: Robert Pająk <pellared@hotmail.com>

CHANGELOG.md

@@ -15,6 +15,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add the `go.opentelemetry.io/otel/trace/embedded` package to be embedded in the exported trace API interfaces. (#4620)
 - Add the `go.opentelemetry.io/otel/trace/noop` package as a default no-op implementation of the trace API. (#4620)
 - Add context propagation in `go.opentelemetry.io/otel/example/dice`. (#4644)
+- Add view configuration to `go.opentelemetry.io/otel/example/prometheus`. (#4649)
 
 ### Deprecated
 
@@ -22,6 +23,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Deprecate `go.opentelemetry.io/otel/example/fib` package is in favor of `go.opentelemetry.io/otel/example/dice`. (#4618)
 - Deprecate `go.opentelemetry.io/otel/trace.NewNoopTracerProvider`.
   Use the added `NewTracerProvider` function in `go.opentelemetry.io/otel/trace/noop` instead. (#4620)
+- Deprecate `go.opentelemetry.io/otel/example/view` package in favor of `go.opentelemetry.io/otel/example/prometheus`. (#4649)
 
 ### Changed
 

example/prometheus/go.mod

@@ -7,6 +7,7 @@ require (
 	go.opentelemetry.io/otel v1.19.0
 	go.opentelemetry.io/otel/exporters/prometheus v0.42.0
 	go.opentelemetry.io/otel/metric v1.19.0
+	go.opentelemetry.io/otel/sdk v1.19.0
 	go.opentelemetry.io/otel/sdk/metric v1.19.0
 )
 
@@ -20,7 +21,6 @@ require (
 	github.com/prometheus/client_model v0.5.0 // indirect
 	github.com/prometheus/common v0.44.0 // indirect
 	github.com/prometheus/procfs v0.11.1 // indirect
-	go.opentelemetry.io/otel/sdk v1.19.0 // indirect
 	go.opentelemetry.io/otel/trace v1.19.0 // indirect
 	golang.org/x/sys v0.13.0 // indirect
 	google.golang.org/protobuf v1.31.0 // indirect

example/prometheus/main.go

@@ -29,9 +29,12 @@ import (
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/exporters/prometheus"
 	api "go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/sdk/instrumentation"
 	"go.opentelemetry.io/otel/sdk/metric"
 )
 
+const meterName = "github.com/open-telemetry/opentelemetry-go/example/prometheus"
+
 func main() {
 	rng := rand.New(rand.NewSource(time.Now().UnixNano()))
 	ctx := context.Background()
@@ -43,8 +46,23 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	provider := metric.NewMeterProvider(metric.WithReader(exporter))
-	meter := provider.Meter("github.com/open-telemetry/opentelemetry-go/example/prometheus")
+	provider := metric.NewMeterProvider(
+		metric.WithReader(exporter),
+		// View to customize histogram buckets and rename a single histogram instrument.
+		metric.WithView(metric.NewView(
+			metric.Instrument{
+				Name:  "baz",
+				Scope: instrumentation.Scope{Name: meterName},
+			},
+			metric.Stream{
+				Name: "new_baz",
+				Aggregation: metric.AggregationExplicitBucketHistogram{
+					Boundaries: []float64{64, 128, 256, 512, 1024, 2048, 4096},
+				},
+			},
+		)),
+	)
+	meter := provider.Meter(meterName)
 
 	// Start the prometheus HTTP server and pass the exporter Collector to it
 	go serveMetrics()
@@ -75,14 +93,14 @@ func main() {
 	}
 
 	// This is the equivalent of prometheus.NewHistogramVec
-	histogram, err := meter.Float64Histogram("baz", api.WithDescription("a very nice histogram"))
+	histogram, err := meter.Float64Histogram("baz", api.WithDescription("a histogram with custom buckets and rename"))
 	if err != nil {
 		log.Fatal(err)
 	}
-	histogram.Record(ctx, 23, opt)
-	histogram.Record(ctx, 7, opt)
-	histogram.Record(ctx, 101, opt)
-	histogram.Record(ctx, 105, opt)
+	histogram.Record(ctx, 136, opt)
+	histogram.Record(ctx, 64, opt)
+	histogram.Record(ctx, 701, opt)
+	histogram.Record(ctx, 830, opt)
 
 	ctx, _ = signal.NotifyContext(ctx, os.Interrupt)
 	<-ctx.Done()

example/view/doc.go

@@ -13,4 +13,6 @@
 // limitations under the License.
 
 // Package main provides a code sample of using metric views to customize instruments.
+//
+// Deprecated: See [go.opentelemetry.io/otel/example/prometheus] instead.
 package main

example/view/go.mod

@@ -1,3 +1,4 @@
+// Deprecated: see go.opentelemetry.io/otel/example/prometheus instead.
 module go.opentelemetry.io/otel/example/view
 
 go 1.20