feat: support OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG settings (#1534) (#1577)

Add support for configuring interceptor trace sampling via OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG.

Signed-off-by: Mikhail Fedosin <[email protected]>

Author: Fedosin

CHANGELOG.md

@@ -39,6 +39,7 @@ This changelog keeps track of work items that have been completed and are ready
 ### Improvements
 
 - **General**: TODO ([#TODO](https://github.com/kedacore/http-add-on/issues/TODO))
+- **Interceptor**: Support `OTEL_TRACES_SAMPLER` and `OTEL_TRACES_SAMPLER_ARG` for trace sampling configuration ([#1534](https://github.com/kedacore/http-add-on/issues/1534))
 
 ### Fixes
 

interceptor/config/tracing.go

@@ -8,7 +8,7 @@ import (
 type Tracing struct {
 	// States whether tracing should be enabled, False by default
 	Enabled bool `env:"OTEL_EXPORTER_OTLP_TRACES_ENABLED" envDefault:"false"`
-	// Sets what tracing export to use, must be one of: console,http/protobuf, grpc
+	// Sets what tracing export to use, must be one of: console, http/protobuf, grpc
 	Exporter string `env:"OTEL_EXPORTER_OTLP_TRACES_PROTOCOL" envDefault:"console"`
 }
 

interceptor/tracing/tracing.go

@@ -17,7 +17,7 @@ import (
 	"github.com/kedacore/http-add-on/interceptor/config"
 )
 
-var serviceName = "keda-http-interceptor"
+const serviceName = "keda-http-interceptor"
 
 func SetupOTelSDK(ctx context.Context, tCfg config.Tracing) (shutdown func(context.Context) error, err error) {
 	var shutdownFuncs []func(context.Context) error
@@ -79,7 +79,6 @@ func newTraceProvider(ctx context.Context, res *resource.Resource, tCfg config.T
 	}
 
 	traceProvider := trace.NewTracerProvider(
-		trace.WithSampler(trace.AlwaysSample()),
 		trace.WithBatcher(traceExporter),
 		trace.WithResource(res),
 	)

interceptor/tracing/tracing_test.go

@@ -9,10 +9,11 @@ import (
 )
 
 func TestTracingConfig(t *testing.T) {
+	t.Setenv("OTEL_EXPORTER_OTLP_TRACES_PROTOCOL", "console")
+
 	tracingCfg := config.MustParseTracing()
 	tracingCfg.Enabled = true
 
-	// check defaults are set correctly
 	assert.Equal(t, "console", tracingCfg.Exporter)
 	assert.True(t, tracingCfg.Enabled)
 }