Removed reader config can be added after (open-telemetry#3244)

exporters/prometheus/confg_test.go

@@ -15,62 +15,33 @@
 package prometheus // import "go.opentelemetry.io/otel/exporters/prometheus"
 
 import (
-	"context"
 	"testing"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/stretchr/testify/assert"
-
-	"go.opentelemetry.io/otel/sdk/metric"
-	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 )
 
-type testExporter struct{}
-
-func (e testExporter) Export(_ context.Context, _ metricdata.ResourceMetrics) error {
-	return nil
-}
-
-func (e testExporter) ForceFlush(_ context.Context) error {
-	return nil
-}
-
-func (e testExporter) Shutdown(_ context.Context) error {
-	return nil
-}
-
 func TestNewConfig(t *testing.T) {
 	registry := prometheus.NewRegistry()
 
 	testCases := []struct {
 		name           string
 		options        []Option
-		wantReaderType metric.Reader
 		wantRegisterer prometheus.Registerer
 		wantGatherer   prometheus.Gatherer
 	}{
 		{
 			name:           "Default",
 			options:        nil,
-			wantReaderType: metric.NewManualReader(),
-			wantRegisterer: prometheus.DefaultRegisterer,
-			wantGatherer:   prometheus.DefaultGatherer,
-		},
-		{
-			name: "WithReader",
-			options: []Option{
-				WithReader(metric.NewPeriodicReader(testExporter{})),
-			},
-			wantReaderType: metric.NewPeriodicReader(testExporter{}),
 			wantRegisterer: prometheus.DefaultRegisterer,
 			wantGatherer:   prometheus.DefaultGatherer,
 		},
+
 		{
 			name: "WithGatherer",
 			options: []Option{
 				WithGatherer(registry),
 			},
-			wantReaderType: metric.NewManualReader(),
 			wantRegisterer: prometheus.DefaultRegisterer,
 			wantGatherer:   registry,
 		},
@@ -79,29 +50,24 @@ func TestNewConfig(t *testing.T) {
 			options: []Option{
 				WithRegisterer(registry),
 			},
-			wantReaderType: metric.NewManualReader(),
 			wantRegisterer: registry,
 			wantGatherer:   prometheus.DefaultGatherer,
 		},
 		{
 			name: "Multiple Options",
 			options: []Option{
-				WithReader(metric.NewPeriodicReader(testExporter{})),
 				WithGatherer(registry),
 				WithRegisterer(registry),
 			},
-			wantReaderType: metric.NewPeriodicReader(testExporter{}),
 			wantRegisterer: registry,
 			wantGatherer:   registry,
 		},
 		{
 			name: "nil options do nothing",
 			options: []Option{
-				WithReader(nil),
 				WithGatherer(nil),
 				WithRegisterer(nil),
 			},
-			wantReaderType: metric.NewManualReader(),
 			wantRegisterer: prometheus.DefaultRegisterer,
 			wantGatherer:   prometheus.DefaultGatherer,
 		},
@@ -110,9 +76,6 @@ func TestNewConfig(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			cfg := newConfig(tt.options...)
 
-			// If no reader is provided you should get a new ManualReader.
-			assert.IsType(t, tt.wantReaderType, cfg.reader)
-
 			// If no Registry is provided you should get the DefaultRegisterer and DefaultGatherer.
 			assert.Equal(t, tt.wantRegisterer, cfg.registerer)
 			assert.Equal(t, tt.wantGatherer, cfg.gatherer)

exporters/prometheus/config.go

@@ -16,12 +16,8 @@ package prometheus // import "go.opentelemetry.io/otel/exporters/prometheus"
 
 import (
 	"github.com/prometheus/client_golang/prometheus"
-
-	"go.opentelemetry.io/otel/sdk/metric"
 ) // config is added here to allow for options expansion in the future.
 type config struct {
-	reader metric.Reader
-
 	registerer prometheus.Registerer
 	gatherer   prometheus.Gatherer
 }
@@ -32,10 +28,6 @@ func newConfig(opts ...Option) config {
 		cfg = opt.apply(cfg)
 	}
 
-	if cfg.reader == nil {
-		cfg.reader = metric.NewManualReader()
-	}
-
 	if cfg.gatherer == nil {
 		cfg.gatherer = prometheus.DefaultGatherer
 	}
@@ -57,15 +49,6 @@ func (fn optionFunc) apply(cfg config) config {
 	return fn(cfg)
 }
 
-// WithReader controls where the Exporter reader Collects() from.  If no reader
-// is passed a ManualReader will be used.
-func WithReader(rdr metric.Reader) Option {
-	return optionFunc(func(cfg config) config {
-		cfg.reader = rdr
-		return cfg
-	})
-}
-
 // WithRegisterer configures which prometheus Registerer the Exporter will
 // register with.  If no registerer is used the prometheus DefaultRegisterer is
 // used.

exporters/prometheus/exporter.go

@@ -52,17 +52,20 @@ type collector struct {
 func New(opts ...Option) (*Exporter, error) {
 	cfg := newConfig(opts...)
 
+	// TODO (#????): Enable some way to configure the reader, but not change temporality.
+	reader := metric.NewManualReader()
+
 	handler := promhttp.HandlerFor(cfg.gatherer, promhttp.HandlerOpts{})
 	collector := &collector{
-		reader: cfg.reader,
+		reader: reader,
 	}
 
 	if err := cfg.registerer.Register(collector); err != nil {
 		return nil, fmt.Errorf("cannot register the collector: %w", err)
 	}
 
 	e := &Exporter{
-		Reader:    cfg.reader,
+		Reader:    reader,
 		Collector: collector,
 
 		handler: handler,