Combine the Push and Pull metric controllers

.github/dependabot.yml

@@ -48,7 +48,7 @@ updates:
       interval: weekly
   -
     package-ecosystem: gomod
-    directory: /example/basic
+    directory: /example/prom-collector
     labels:
       - dependencies
       - go

.gitignore

@@ -10,7 +10,6 @@ coverage.*
 
 gen/
 
-/example/basic/basic
 /example/grpc/client/client
 /example/grpc/server/server
 /example/http/client/client
@@ -19,5 +18,6 @@ gen/
 /example/namedtracer/namedtracer
 /example/opencensus/opencensus
 /example/prometheus/prometheus
+/example/prom-collector/prom-collector
 /example/zipkin/zipkin
 /example/otel-collector/otel-collector

CHANGELOG.md

@@ -17,6 +17,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Rename `export.SpanData` to `export.SpanSnapshot` and use it only for exporting spans. (#1360)
 - Store the parent's full `SpanContext` rather than just its span ID in the `span` struct. (#1360)
 - Improve span duration accuracy. (#1360)
+- Metric Push and Pull Controller components are combined into a single "basic" Controller:
+  - `WithExporter()` and `Start()` to configure Push behavior
+  - `Start()` is optional; use `Collect()` and `ForEach()` for Pull behavior
+  - `Start()` and `Stop()` accept Context. (#1378)
 
 ### Removed
 
@@ -37,7 +41,6 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Bump `github.com/google/go-cmp` from 0.5.3 to 0.5.4 (#1374)
 - Bump `github.com/golangci/golangci-lint` in `/internal/tools` (#1375)
 
-
 ### Fixed
 
 - Metric SDK `SumObserver` and `UpDownSumObserver` instruments correctness fixes. (#1381)

example/otel-collector/main.go

@@ -30,8 +30,8 @@ import (
 	"go.opentelemetry.io/otel/label"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/propagation"
-	"go.opentelemetry.io/otel/sdk/metric/controller/push"
-	"go.opentelemetry.io/otel/sdk/metric/processor/basic"
+	controller "go.opentelemetry.io/otel/sdk/metric/controller/basic"
+	processor "go.opentelemetry.io/otel/sdk/metric/processor/basic"
 	"go.opentelemetry.io/otel/sdk/metric/selector/simple"
 	"go.opentelemetry.io/otel/sdk/resource"
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
@@ -71,25 +71,25 @@ func initProvider() func() {
 		sdktrace.WithSpanProcessor(bsp),
 	)
 
-	pusher := push.New(
-		basic.New(
+	controller := controller.New(
+		processor.New(
 			simple.NewWithExactDistribution(),
 			exp,
 		),
-		exp,
-		push.WithPeriod(2*time.Second),
+		controller.WithExporter(exp),
+		controller.WithCollectPeriod(2*time.Second),
 	)
 
 	// set global propagator to tracecontext (the default is no-op).
 	otel.SetTextMapPropagator(propagation.TraceContext{})
 	otel.SetTracerProvider(tracerProvider)
-	otel.SetMeterProvider(pusher.MeterProvider())
-	pusher.Start()
+	otel.SetMeterProvider(controller.MeterProvider())
+	handleErr(controller.Start(context.Background()), "failed to start controller")
 
 	return func() {
 		handleErr(tracerProvider.Shutdown(ctx), "failed to shutdown provider")
 		handleErr(exp.Shutdown(ctx), "failed to stop exporter")
-		pusher.Stop() // pushes any last exports to the receiver
+		handleErr(controller.Stop(context.Background()), "failed to stop controller")
 	}
 }
 

example/prom-collector/README.md

@@ -0,0 +1,3 @@
+This example demonstrates a metrics export pipeline that supports
+Prometheus (pull) and simultaneously exports OTLP to an OpenTelemetry
+endpoint (push).

example/prom-collector/go.mod

@@ -0,0 +1,18 @@
+module go.opentelemetry.io/otel/example/prom-collector
+
+go 1.14
+
+replace (
+	go.opentelemetry.io/otel => ../..
+	go.opentelemetry.io/otel/exporters/metric/prometheus => ../../exporters/metric/prometheus
+	go.opentelemetry.io/otel/exporters/otlp => ../../exporters/otlp
+	go.opentelemetry.io/otel/sdk => ../../sdk
+)
+
+require (
+	go.opentelemetry.io/otel v0.15.0
+	go.opentelemetry.io/otel/exporters/metric/prometheus v0.14.0
+	go.opentelemetry.io/otel/exporters/otlp v0.14.0
+	go.opentelemetry.io/otel/sdk v0.15.0
+	google.golang.org/grpc v1.32.0
+)