set default tracing sample rate to 1.0

config/envoyconfig/tracing.go

@@ -56,8 +56,17 @@ func applyTracingConfig(
 			maxPathTagLength = max(64, uint32(num))
 		}
 	}
+	sampleRate := 1.0
+	if value, ok := os.LookupEnv("OTEL_TRACES_SAMPLER_ARG"); ok {
+		if rate, err := strconv.ParseFloat(value, 64); err == nil {
+			sampleRate = rate
+		}
+	}
+	if opts.TracingSampleRate != nil {
+		sampleRate = *opts.TracingSampleRate
+	}
 	mgr.Tracing = &envoy_extensions_filters_network_http_connection_manager.HttpConnectionManager_Tracing{
-		RandomSampling:    &envoy_type_v3.Percent{Value: opts.TracingSampleRate * 100},
+		RandomSampling:    &envoy_type_v3.Percent{Value: max(0.0, min(1.0, sampleRate)) * 100},
 		Verbose:           true,
 		SpawnUpstreamSpan: wrapperspb.Bool(true),
 		Provider: &tracev3.Tracing_Http{

config/options.go

@@ -210,10 +210,10 @@ type Options struct {
 	MetricsClientCA           string `mapstructure:"metrics_client_ca" yaml:"metrics_client_ca,omitempty"`
 	MetricsClientCAFile       string `mapstructure:"metrics_client_ca_file" yaml:"metrics_client_ca_file,omitempty"`
 
-	TracingSampleRate   float64 `mapstructure:"tracing_sample_rate" yaml:"tracing_sample_rate,omitempty"`
+	TracingSampleRate   *float64 `mapstructure:"tracing_sample_rate" yaml:"tracing_sample_rate,omitempty"`
-	TracingProvider     string  `mapstructure:"tracing_provider" yaml:"tracing_provider,omitempty"`
+	TracingProvider     string   `mapstructure:"tracing_provider" yaml:"tracing_provider,omitempty"`
-	TracingOTLPEndpoint string  `mapstructure:"tracing_otlp_endpoint" yaml:"tracing_otlp_endpoint,omitempty"`
+	TracingOTLPEndpoint string   `mapstructure:"tracing_otlp_endpoint" yaml:"tracing_otlp_endpoint,omitempty"`
-	TracingOTLPProtocol string  `mapstructure:"tracing_otlp_protocol" yaml:"tracing_otlp_protocol,omitempty"`
+	TracingOTLPProtocol string   `mapstructure:"tracing_otlp_protocol" yaml:"tracing_otlp_protocol,omitempty"`
 
 	// Deprecated: this field is ignored.
 	// Configure tracing using the OTLP options or environment variables.
@@ -313,7 +313,6 @@ var defaultOptions = Options{
 	GRPCAddr:                 ":443",
 	GRPCClientTimeout:        10 * time.Second, // Try to withstand transient service failures for a single request
 	AuthenticateCallbackPath: "/oauth2/callback",
-	TracingSampleRate:        0.0001,
 
 	AutocertOptions: AutocertOptions{
 		Folder: dataDir(),
@@ -1518,7 +1517,7 @@ func (o *Options) ApplySettings(ctx context.Context, certsIndex *cryptutil.Certi
 	set(&o.TracingProvider, settings.TracingProvider)
 	set(&o.TracingOTLPEndpoint, settings.TracingOtlpEndpoint)
 	set(&o.TracingOTLPProtocol, settings.TracingOtlpProtocol)
-	set(&o.TracingSampleRate, settings.TracingSampleRate)
+	setOptional(&o.TracingSampleRate, settings.TracingSampleRate)
 	set(&o.TracingDatadogAddress, settings.TracingDatadogAddress)
 	set(&o.TracingJaegerCollectorEndpoint, settings.TracingJaegerCollectorEndpoint)
 	set(&o.TracingJaegerAgentEndpoint, settings.TracingJaegerAgentEndpoint)
@@ -1608,7 +1607,7 @@ func (o *Options) ToProto() *config.Config {
 	settings.MetricsCertificate = toCertificateOrFromFile(o.MetricsCertificate, o.MetricsCertificateKey, o.MetricsCertificateFile, o.MetricsCertificateKeyFile)
 	copySrcToOptionalDest(&settings.MetricsClientCa, valueOrFromFileBase64(o.MetricsClientCA, o.MetricsClientCAFile))
 	copySrcToOptionalDest(&settings.TracingProvider, &o.TracingProvider)
-	copySrcToOptionalDest(&settings.TracingSampleRate, &o.TracingSampleRate)
+	settings.TracingSampleRate = o.TracingSampleRate
 	copySrcToOptionalDest(&settings.TracingOtlpEndpoint, &o.TracingOTLPEndpoint)
 	copySrcToOptionalDest(&settings.TracingOtlpProtocol, &o.TracingOTLPProtocol)
 	copySrcToOptionalDest(&settings.TracingDatadogAddress, &o.TracingDatadogAddress)

internal/testenv/environment.go

@@ -599,7 +599,6 @@ func (e *environment) Start() {
 		log.AccessLogFieldUserAgent,
 		log.AccessLogFieldClientCertificate,
 	}
-	cfg.Options.TracingSampleRate = 1.0
 
 	e.src = &configSource{cfg: cfg}
 	e.AddTask(TaskFunc(func(ctx context.Context) error {

internal/testenv/selftests/tracing_test.go

@@ -193,7 +193,8 @@ func (s *SamplingTestSuite) SetupTest() {
 	s.notSampled.Store(0)
 
 	s.env.Add(testenv.ModifierFunc(func(_ context.Context, cfg *config.Config) {
-		cfg.Options.TracingSampleRate = 0.5
+		half := 0.5
+		cfg.Options.TracingSampleRate = &half
 	}))
 	s.env.Add(scenarios.NewIDP([]*scenarios.User{
 		{