jaegerremote: Add WithSamplingStrategyFetcher option

CHANGELOG.md

@@ -19,6 +19,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add `NewMiddleware` function in `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp`. (#2964)
 - The `go.opentelemetry.io/contrib/exporters/autoexport` package to provide configuration of trace exporters with useful defaults and environment variable support. (#2753, #4100, #4130, #4132, #4134)
 - `WithRouteTag` in `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp` adds HTTP route attribute to metrics. (#615)
+- Add `WithSamplingStrategyFetcher` which sets custom fetcher implementation. (#4045)
 - Add `WithSpanOptions` option in `go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc`. (#3768)
 - Add testing support for Go 1.21. (#4233)
 

samplers/jaegerremote/sampler_remote.go

@@ -39,8 +39,8 @@ const (
 	defaultSamplingOperationNameLateBinding = true
 )
 
-// samplingStrategyFetcher is used to fetch sampling strategy updates from remote server.
-type samplingStrategyFetcher interface {
+// SamplingStrategyFetcher is used to fetch sampling strategy updates from remote server.
+type SamplingStrategyFetcher interface {
 	Fetch(service string) ([]byte, error)
 }
 

samplers/jaegerremote/sampler_remote_options.go

@@ -28,7 +28,7 @@ type config struct {
 	sampler                 trace.Sampler
 	samplingServerURL       string
 	samplingRefreshInterval time.Duration
-	samplingFetcher         samplingStrategyFetcher
+	samplingFetcher         SamplingStrategyFetcher
 	samplingParser          samplingStrategyParser
 	updaters                []samplerUpdater
 	posParams               perOperationSamplerParams
@@ -124,7 +124,7 @@ func WithLogger(logger logr.Logger) Option {
 }
 
 // samplingStrategyFetcher creates a Option that initializes sampling strategy fetcher.
-func withSamplingStrategyFetcher(fetcher samplingStrategyFetcher) Option {
+func WithSamplingStrategyFetcher(fetcher SamplingStrategyFetcher) Option {
 	return optionFunc(func(c *config) {
 		c.samplingFetcher = fetcher
 	})

samplers/jaegerremote/sampler_remote_test.go

@@ -20,6 +20,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"net/http"
 	"sync"
 	"testing"
 	"time"
@@ -46,7 +47,7 @@ func TestRemotelyControlledSampler_updateConcurrentSafe(t *testing.T) {
 		WithInitialSampler(initSampler),
 		WithSamplingServerURL("my url"),
 		WithSamplingRefreshInterval(time.Millisecond),
-		withSamplingStrategyFetcher(fetcher),
+		WithSamplingStrategyFetcher(fetcher),
 		withSamplingStrategyParser(parser),
 		withUpdaters(updaters...),
 	)
@@ -117,7 +118,7 @@ func TestRemoteSamplerOptions(t *testing.T) {
 		WithInitialSampler(initSampler),
 		WithSamplingServerURL("my url"),
 		WithSamplingRefreshInterval(42*time.Second),
-		withSamplingStrategyFetcher(fetcher),
+		WithSamplingStrategyFetcher(fetcher),
 		withSamplingStrategyParser(parser),
 		withUpdaters(updaters...),
 		WithLogger(logger),
@@ -302,7 +303,7 @@ func TestRemotelyControlledSampler_ImmediatelyUpdateOnStartup(t *testing.T) {
 		WithInitialSampler(initSampler),
 		WithSamplingServerURL("my url"),
 		WithSamplingRefreshInterval(10*time.Minute),
-		withSamplingStrategyFetcher(fetcher),
+		WithSamplingStrategyFetcher(fetcher),
 		withSamplingStrategyParser(parser),
 		withUpdaters(updaters...),
 	)
@@ -586,3 +587,16 @@ func TestSamplingStrategyParserImpl_Error(t *testing.T) {
 	require.Error(t, err, "output: %+v", val)
 	require.Contains(t, err.Error(), `unknown value "foo_bar"`)
 }
+
+func TestDefaultSamplingStrategyFetcher_Panic(t *testing.T) {
+	defaultTransport := http.DefaultTransport
+	http.DefaultTransport = http.NewFileTransport(http.Dir("/"))
+
+	t.Cleanup(func() {
+		http.DefaultTransport = defaultTransport
+	})
+
+	require.Panics(t, func() {
+		newHTTPSamplingStrategyFetcher("")
+	})
+}