Fix: error logged on empty OTEL_TRACES_SAMPLER_ARG (#6511)

Co-authored-by: Damien Mathieu <[email protected]>

CHANGELOG.md

@@ -12,6 +12,10 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 - Generate server metrics with semantic conventions v1.26 in `go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp` when `OTEL_SEMCONV_STABILITY_OPT_IN` is set to `http/dup`. (#6411)
 
+### Fixed
+
+- Fix error logged by Jaeger remote sampler on empty or unset `OTEL_TRACES_SAMPLER_ARG` environment variable (#6511)
+
 ## [1.33.0/0.58.0/0.27.0/0.13.0/0.8.0/0.6.0/0.5.0] - 2024-12-12
 
 ### Added

samplers/jaegerremote/sampler_remote_options.go

@@ -46,7 +46,12 @@ func getEnvOptions() ([]Option, []error) {
 	// list of errors which will be logged once logger is set by the user
 	var errs []error
 
-	args := strings.Split(os.Getenv("OTEL_TRACES_SAMPLER_ARG"), ",")
+	rawEnvArgs := os.Getenv("OTEL_TRACES_SAMPLER_ARG")
+	if rawEnvArgs == "" {
+		return nil, nil
+	}
+
+	args := strings.Split(rawEnvArgs, ",")
 	for _, arg := range args {
 		keyValue := strings.Split(arg, "=")
 		if len(keyValue) != 2 {

samplers/jaegerremote/sampler_remote_test.go

@@ -22,6 +22,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"fmt"
+	"os"
 	"sync"
 	"testing"
 	"time"
@@ -653,4 +654,33 @@ func TestEnvVarSettingForNewTracer(t *testing.T) {
 			}
 		})
 	}
+
+	t.Run("No-op when env var not set or empty", func(t *testing.T) {
+		for _, test := range []struct {
+			desc     string
+			envSetup func()
+		}{
+			{
+				"env var empty",
+				func() { t.Setenv("OTEL_TRACES_SAMPLER_ARG", "") },
+			},
+			{
+				"env var unset",
+				func() {
+					// t.Setenv to restore this environment variable at the end of the test
+					t.Setenv("OTEL_TRACES_SAMPLER_ARG", "")
+					// unset it during the test
+					require.NoError(t, os.Unsetenv("OTEL_TRACES_SAMPLER_ARG"))
+				},
+			},
+		} {
+			t.Run(test.desc, func(t *testing.T) {
+				test.envSetup()
+				opts, errs := getEnvOptions()
+
+				require.Empty(t, errs)
+				require.Empty(t, opts)
+			})
+		}
+	})
 }