add bucket boundaries option to override defaults

docs/docs/sdk/otelcourier.md

@@ -13,6 +13,7 @@ Package otelcourier instruments the github.com/gojek/courier\-go package.
 - [Constants](#constants)
 - [Variables](#variables)
 - [func DefaultTopicAttributeTransformer\(\_ context.Context, topic string\) string](#DefaultTopicAttributeTransformer)
+- [type BucketBoundaries](#BucketBoundaries)
 - [type OTel](#OTel)
   - [func New\(service string, opts ...Option\) \*OTel](#New)
   - [func \(t \*OTel\) ApplyMiddlewares\(c UseMiddleware\)](#OTel.ApplyMiddlewares)
@@ -83,6 +84,17 @@ func DefaultTopicAttributeTransformer(_ context.Context, topic string) string
 
 DefaultTopicAttributeTransformer is the default transformer for topic attribute.
 
+<a name="BucketBoundaries"></a>
+## type [BucketBoundaries](https://github.com/gojek/courier-go/blob/main/otelcourier/options.go#L66-L68)
+
+BucketBoundaries helps override default histogram bucket boundaries for metrics.
+
+```go
+type BucketBoundaries struct {
+    Publisher, Subscriber, Unsubscriber, Callback []float64
+}
+```
+
 <a name="OTel"></a>
 ## type [OTel](https://github.com/gojek/courier-go/blob/main/otelcourier/otel.go#L29-L41)
 

otelcourier/metric.go

@@ -10,23 +10,30 @@ import (
 	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
 )
 
-var metricFlows = map[tracePath]struct {
-	name       string
-	boundaries []float64
-}{
-	tracePublisher:    {name: "publish", boundaries: prom.ExponentialBucketsRange(0.0001, 1, 10)},
-	traceSubscriber:   {name: "subscribe", boundaries: prom.ExponentialBucketsRange(0.001, 1, 7)},
-	traceUnsubscriber: {name: "unsubscribe", boundaries: prom.ExponentialBucketsRange(0.001, 1, 7)},
-	traceCallback:     {name: "subscribe.callback", boundaries: prom.ExponentialBucketsRange(0.001, 10, 15)},
-}
+var (
+	defaultBoundaries   = prom.ExponentialBucketsRange(0.001, 1, 7)
+	defBucketBoundaries = map[tracePath][]float64{
+		tracePublisher:    prom.ExponentialBucketsRange(0.0001, 1, 10),
+		traceSubscriber:   defaultBoundaries,
+		traceUnsubscriber: defaultBoundaries,
+		traceCallback:     prom.ExponentialBucketsRange(0.001, 10, 15),
+	}
+
+	metricFlows = map[tracePath]string{
+		tracePublisher:    "publish",
+		traceSubscriber:   "subscribe",
+		traceUnsubscriber: "unsubscribe",
+		traceCallback:     "subscribe.callback",
+	}
+)
 
-func (t *OTel) initRecorders() {
+func (t *OTel) initRecorders(histogramBoundaries map[tracePath][]float64) {
 	for path, flow := range metricFlows {
 		if !t.tracePaths.match(path) {
 			continue
 		}
 
-		t.rc[path] = t.newRecorder(flow.name, flow.boundaries)
+		t.rc[path] = t.newRecorder(flow, histogramBoundaries[path])
 	}
 
 	if t.infoHandler != nil {

otelcourier/options.go

@@ -11,7 +11,7 @@ import (
 )
 
 // Option helps configure trace options.
-type Option interface{ apply(*traceOptions) }
+type Option interface{ apply(*options) }
 
 // TopicAttributeTransformer helps transform topic before making an attribute for it.
 // It is used in metric recording only. Traces use the original topic.
@@ -20,31 +20,31 @@ type TopicAttributeTransformer func(context.Context, string) string
 // WithTracerProvider specifies a tracer provider to use for creating a tracer.
 // If none is specified, the global provider is used.
 func WithTracerProvider(provider oteltrace.TracerProvider) Option {
-	return optFn(func(opts *traceOptions) { opts.tracerProvider = provider })
+	return optFn(func(opts *options) { opts.tracerProvider = provider })
 }
 
 // WithMeterProvider specifies a meter provider to use for creating a meter.
 // If none is specified, the global provider is used.
 func WithMeterProvider(provider metric.MeterProvider) Option {
-	return optFn(func(opts *traceOptions) { opts.meterProvider = provider })
+	return optFn(func(opts *options) { opts.meterProvider = provider })
 }
 
 // WithTextMapPropagator specifies the propagator to use for extracting/injecting key-value texts.
 // If none is specified, the global provider is used.
 func WithTextMapPropagator(propagator propagation.TextMapPropagator) Option {
-	return optFn(func(opts *traceOptions) { opts.propagator = propagator })
+	return optFn(func(opts *options) { opts.propagator = propagator })
 }
 
 // WithTextMapCarrierExtractFunc is used to specify the function which should be used to
 // extract propagation.TextMapCarrier from the ongoing context.Context.
 func WithTextMapCarrierExtractFunc(fn func(context.Context) propagation.TextMapCarrier) Option {
-	return optFn(func(opts *traceOptions) { opts.textMapCarrierExtractor = fn })
+	return optFn(func(opts *options) { opts.textMapCarrierExtractor = fn })
 }
 
 // WithInfoHandlerFrom is used to specify the handler which should be used to
 // extract client information from the courier.Client instance.
 func WithInfoHandlerFrom(c interface{ InfoHandler() http.Handler }) Option {
-	return optFn(func(opts *traceOptions) { opts.infoHandler = c.InfoHandler() })
+	return optFn(func(opts *options) { opts.infoHandler = c.InfoHandler() })
 }
 
 // DisableCallbackTracing disables implicit tracing on subscription callbacks.
@@ -62,19 +62,43 @@ var DisableUnsubscriberTracing = &disableTracePathOpt{traceUnsubscriber}
 // DefaultTopicAttributeTransformer is the default transformer for topic attribute.
 func DefaultTopicAttributeTransformer(_ context.Context, topic string) string { return topic }
 
+// BucketBoundaries helps override default histogram bucket boundaries for metrics.
+type BucketBoundaries struct {
+	Publisher, Subscriber, Unsubscriber, Callback []float64
+}
+
+func (b BucketBoundaries) apply(opts *options) {
+	if b.Publisher != nil {
+		opts.histogramBoundaries[tracePublisher] = b.Publisher
+	}
+
+	if b.Subscriber != nil {
+		opts.histogramBoundaries[traceSubscriber] = b.Subscriber
+	}
+
+	if b.Unsubscriber != nil {
+		opts.histogramBoundaries[traceUnsubscriber] = b.Unsubscriber
+	}
+
+	if b.Callback != nil {
+		opts.histogramBoundaries[traceCallback] = b.Callback
+	}
+}
+
 /// private types and functions
 
-type optFn func(*traceOptions)
+type optFn func(*options)
 
-func (fn optFn) apply(opts *traceOptions) { fn(opts) }
+func (fn optFn) apply(opts *options) { fn(opts) }
 
-func defaultOptions() *traceOptions {
-	return &traceOptions{
-		tracerProvider:   otel.GetTracerProvider(),
-		meterProvider:    otel.GetMeterProvider(),
-		propagator:       otel.GetTextMapPropagator(),
-		tracePaths:       tracePublisher + traceSubscriber + traceUnsubscriber + traceCallback,
-		topicTransformer: DefaultTopicAttributeTransformer,
+func defaultOptions() *options {
+	return &options{
+		tracerProvider:      otel.GetTracerProvider(),
+		meterProvider:       otel.GetMeterProvider(),
+		propagator:          otel.GetTextMapPropagator(),
+		tracePaths:          tracePublisher + traceSubscriber + traceUnsubscriber + traceCallback,
+		topicTransformer:    DefaultTopicAttributeTransformer,
+		histogramBoundaries: defBucketBoundaries,
 	}
 }
 
@@ -85,14 +109,15 @@ const (
 	traceCallback
 )
 
-type traceOptions struct {
+type options struct {
 	tracerProvider          oteltrace.TracerProvider
 	meterProvider           metric.MeterProvider
 	propagator              propagation.TextMapPropagator
 	textMapCarrierExtractor func(context.Context) propagation.TextMapCarrier
 	tracePaths              tracePath
 	topicTransformer        TopicAttributeTransformer
 	infoHandler             http.Handler
+	histogramBoundaries     map[tracePath][]float64
 }
 
 type tracePath uint
@@ -101,6 +126,6 @@ func (tp tracePath) match(o tracePath) bool { return tp&o != 0 }
 
 type disableTracePathOpt struct{ tracePath }
 
-func (o *disableTracePathOpt) apply(opts *traceOptions) { opts.tracePaths &^= o.tracePath }
+func (o *disableTracePathOpt) apply(opts *options) { opts.tracePaths &^= o.tracePath }
 
-func (t TopicAttributeTransformer) apply(opts *traceOptions) { opts.topicTransformer = t }
+func (t TopicAttributeTransformer) apply(opts *options) { opts.topicTransformer = t }

otelcourier/options_test.go

@@ -14,112 +14,120 @@ func TestOption(t *testing.T) {
 	testcases := []struct {
 		name    string
 		options []Option
-		want    *traceOptions
+		want    *options
 	}{
 		{
 			name: "DefaultOptions",
-			want: &traceOptions{
-				tracerProvider: otel.GetTracerProvider(),
-				meterProvider:  otel.GetMeterProvider(),
-				propagator:     otel.GetTextMapPropagator(),
-				tracePaths:     tracePublisher + traceSubscriber + traceUnsubscriber + traceCallback,
+			want: &options{
+				tracerProvider:      otel.GetTracerProvider(),
+				meterProvider:       otel.GetMeterProvider(),
+				propagator:          otel.GetTextMapPropagator(),
+				tracePaths:          tracePublisher + traceSubscriber + traceUnsubscriber + traceCallback,
+				histogramBoundaries: defBucketBoundaries,
 			},
 		},
 		{
 			name:    "DisablePublisher",
 			options: []Option{DisablePublisherTracing},
-			want: &traceOptions{
-				tracerProvider: otel.GetTracerProvider(),
-				meterProvider:  otel.GetMeterProvider(),
-				propagator:     otel.GetTextMapPropagator(),
-				tracePaths:     traceSubscriber + traceUnsubscriber + traceCallback,
+			want: &options{
+				tracerProvider:      otel.GetTracerProvider(),
+				meterProvider:       otel.GetMeterProvider(),
+				propagator:          otel.GetTextMapPropagator(),
+				tracePaths:          traceSubscriber + traceUnsubscriber + traceCallback,
+				histogramBoundaries: defBucketBoundaries,
 			},
 		},
 		{
 			name:    "DisableSubscriber",
 			options: []Option{DisableSubscriberTracing},
-			want: &traceOptions{
-				tracerProvider: otel.GetTracerProvider(),
-				meterProvider:  otel.GetMeterProvider(),
-				propagator:     otel.GetTextMapPropagator(),
-				tracePaths:     tracePublisher + traceUnsubscriber + traceCallback,
+			want: &options{
+				tracerProvider:      otel.GetTracerProvider(),
+				meterProvider:       otel.GetMeterProvider(),
+				propagator:          otel.GetTextMapPropagator(),
+				tracePaths:          tracePublisher + traceUnsubscriber + traceCallback,
+				histogramBoundaries: defBucketBoundaries,
 			},
 		},
 		{
 			name:    "DisableUnsubscriber",
 			options: []Option{DisableUnsubscriberTracing},
-			want: &traceOptions{
-				tracerProvider: otel.GetTracerProvider(),
-				meterProvider:  otel.GetMeterProvider(),
-				propagator:     otel.GetTextMapPropagator(),
-				tracePaths:     tracePublisher + traceSubscriber + traceCallback,
+			want: &options{
+				tracerProvider:      otel.GetTracerProvider(),
+				meterProvider:       otel.GetMeterProvider(),
+				propagator:          otel.GetTextMapPropagator(),
+				tracePaths:          tracePublisher + traceSubscriber + traceCallback,
+				histogramBoundaries: defBucketBoundaries,
 			},
 		},
 		{
 			name:    "DisableCallback",
 			options: []Option{DisableCallbackTracing},
-			want: &traceOptions{
-				tracerProvider: otel.GetTracerProvider(),
-				meterProvider:  otel.GetMeterProvider(),
-				propagator:     otel.GetTextMapPropagator(),
-				tracePaths:     tracePublisher + traceSubscriber + traceUnsubscriber,
+			want: &options{
+				tracerProvider:      otel.GetTracerProvider(),
+				meterProvider:       otel.GetMeterProvider(),
+				propagator:          otel.GetTextMapPropagator(),
+				tracePaths:          tracePublisher + traceSubscriber + traceUnsubscriber,
+				histogramBoundaries: defBucketBoundaries,
 			},
 		},
 		{
 			name:    "DisableCallbackTwice",
 			options: []Option{DisableCallbackTracing, DisableCallbackTracing},
-			want: &traceOptions{
-				tracerProvider: otel.GetTracerProvider(),
-				meterProvider:  otel.GetMeterProvider(),
-				propagator:     otel.GetTextMapPropagator(),
-				tracePaths:     tracePublisher + traceSubscriber + traceUnsubscriber,
+			want: &options{
+				tracerProvider:      otel.GetTracerProvider(),
+				meterProvider:       otel.GetMeterProvider(),
+				propagator:          otel.GetTextMapPropagator(),
+				tracePaths:          tracePublisher + traceSubscriber + traceUnsubscriber,
+				histogramBoundaries: defBucketBoundaries,
 			},
 		},
 		{
 			name:    "DisableAllButCallback",
 			options: []Option{DisablePublisherTracing, DisableSubscriberTracing, DisableUnsubscriberTracing},
-			want: &traceOptions{
-				tracerProvider: otel.GetTracerProvider(),
-				meterProvider:  otel.GetMeterProvider(),
-				propagator:     otel.GetTextMapPropagator(),
-				tracePaths:     traceCallback,
+			want: &options{
+				tracerProvider:      otel.GetTracerProvider(),
+				meterProvider:       otel.GetMeterProvider(),
+				propagator:          otel.GetTextMapPropagator(),
+				tracePaths:          traceCallback,
+				histogramBoundaries: defBucketBoundaries,
 			},
 		},
 		{
 			name:    "DisableTwoTracers",
 			options: []Option{DisablePublisherTracing, DisableSubscriberTracing},
-			want: &traceOptions{
-				tracerProvider: otel.GetTracerProvider(),
-				meterProvider:  otel.GetMeterProvider(),
-				propagator:     otel.GetTextMapPropagator(),
-				tracePaths:     traceUnsubscriber + traceCallback,
+			want: &options{
+				tracerProvider:      otel.GetTracerProvider(),
+				meterProvider:       otel.GetMeterProvider(),
+				propagator:          otel.GetTextMapPropagator(),
+				tracePaths:          traceUnsubscriber + traceCallback,
+				histogramBoundaries: defBucketBoundaries,
 			},
 		},
 	}
 
 	for _, tt := range testcases {
 		t.Run(tt.name, func(t *testing.T) {
-			to := defaultOptions()
+			o := defaultOptions()
 
 			for _, opt := range tt.options {
-				opt.apply(to)
+				opt.apply(o)
 			}
 
 			// Ignore topicTransformer
-			to.topicTransformer = nil
+			o.topicTransformer = nil
 
-			assert.Equal(t, tt.want, to)
+			assert.Equal(t, tt.want, o)
 		})
 	}
 
 	extractorFn := func(_ context.Context) propagation.TextMapCarrier { return &propagation.MapCarrier{} }
 
 	t.Run("TextMapCarrierExtractor", func(t *testing.T) {
-		to := defaultOptions()
+		o := defaultOptions()
 
-		WithTextMapCarrierExtractFunc(extractorFn).apply(to)
+		WithTextMapCarrierExtractFunc(extractorFn).apply(o)
 
-		assert.Equal(t, fmt.Sprintf("%p", extractorFn), fmt.Sprintf("%p", to.textMapCarrierExtractor))
+		assert.Equal(t, fmt.Sprintf("%p", extractorFn), fmt.Sprintf("%p", o.textMapCarrierExtractor))
 	})
 
 	t.Run("DefaultTopicAttributeTransformer", func(t *testing.T) {
@@ -129,10 +137,28 @@ func TestOption(t *testing.T) {
 	customTransformer := func(_ context.Context, topic string) string { return topic + "custom" }
 
 	t.Run("CustomTopicAttributeTransformer", func(t *testing.T) {
-		to := defaultOptions()
+		o := defaultOptions()
 
-		TopicAttributeTransformer(customTransformer).apply(to)
+		TopicAttributeTransformer(customTransformer).apply(o)
 
-		assert.Equal(t, "topiccustom", to.topicTransformer(context.Background(), "topic"))
+		assert.Equal(t, "topiccustom", o.topicTransformer(context.Background(), "topic"))
+	})
+
+	t.Run("BucketBoundaries", func(t *testing.T) {
+		o := defaultOptions()
+
+		bb := BucketBoundaries{
+			Publisher:    []float64{1, 2, 3},
+			Subscriber:   []float64{4, 5, 6},
+			Unsubscriber: []float64{7, 8, 9},
+			Callback:     []float64{10, 11, 12},
+		}
+
+		bb.apply(o)
+
+		assert.Equal(t, []float64{1, 2, 3}, o.histogramBoundaries[tracePublisher])
+		assert.Equal(t, []float64{4, 5, 6}, o.histogramBoundaries[traceSubscriber])
+		assert.Equal(t, []float64{7, 8, 9}, o.histogramBoundaries[traceUnsubscriber])
+		assert.Equal(t, []float64{10, 11, 12}, o.histogramBoundaries[traceCallback])
 	})
 }