poc(ddtrace/tracer): migrate enabled (RC)

ddtrace/tracer/option.go

@@ -119,6 +119,10 @@ var (
 type config struct {
 	*knobs.Scope
 
+	dynamic struct {
+		// enabled reports whether tracing is enabled.
+		enabled dynamicConfig[bool]
+	}
 
 	// debug, when true, writes details to logs.
 	debug bool
@@ -235,9 +239,6 @@ type config struct {
 	// profilerEndpoints specifies whether profiler endpoint filtering is enabled.
 	profilerEndpoints bool
 
-	// enabled reports whether tracing is enabled.
-	enabled dynamicConfig[bool]
-
 	// enableHostnameDetection specifies whether the tracer should enable hostname detection.
 	enableHostnameDetection bool
 
@@ -295,6 +296,26 @@ var (
 )
 
 var (
+	enabled = knobs.Register(&knobs.Definition[bool]{
+		Default: true,
+		EnvVars: []knobs.EnvVar{
+			{
+				Key: "DD_TRACE_ENABLED",
+			},
+			{
+				Key:       "OTEL_TRACES_EXPORTER",
+				Transform: mapEnabled,
+			},
+		},
+		Parse: func(s string) (bool, error) {
+			if s == "" {
+				// Short-circuit if the value is empty, to avoid parsing errors.
+				return true, nil
+			}
+			return strconv.ParseBool(s)
+		},
+	})
+
 	// globalSampleRate holds sample rate read from environment variables.
 	globalSampleRate = knobs.Register(&knobs.Definition[float64]{
 		Default: math.NaN(),
@@ -450,9 +471,10 @@ func newConfig(opts ...StartOption) *config {
 	c.runtimeMetricsV2 = internal.BoolEnv("DD_RUNTIME_METRICS_V2_ENABLED", false)
 	c.debug = internal.BoolVal(getDDorOtelConfig("debugMode"), false)
 	c.logDirectory = os.Getenv("DD_TRACE_LOG_DIRECTORY")
-	c.enabled = newDynamicConfig("tracing_enabled", internal.BoolVal(getDDorOtelConfig("enabled"), true), func(b bool) bool { return true }, equal[bool])
+	c.dynamic.enabled = newDynamicConfig("tracing_enabled", knobs.GetScope(c.Scope, enabled), func(b bool) bool { knobs.SetScope(c.Scope, enabled, knobs.Code, b); return true }, equal[bool])
 	if _, ok := os.LookupEnv("DD_TRACE_ENABLED"); ok {
-		c.enabled.cfgOrigin = telemetry.OriginEnvVar
+		// TODO: shouldn't we track this for the OTEL_TRACES_EXPORTER case?
+		c.dynamic.enabled.cfgOrigin = telemetry.OriginEnvVar
 	}
 	c.profilerEndpoints = internal.BoolEnv(traceprof.EndpointEnvVar, true)
 	c.profilerHotspots = internal.BoolEnv(traceprof.CodeHotspotsEnvVar, true)
@@ -567,7 +589,7 @@ func newConfig(opts ...StartOption) *config {
 		log.SetLevel(log.LevelDebug)
 	}
 	// if using stdout or traces are disabled, agent is disabled
-	agentDisabled := c.logToStdout || !c.enabled.current
+	agentDisabled := c.logToStdout || !knobs.GetScope(c.Scope, enabled)
 	c.agent = loadAgentFeatures(agentDisabled, c.agentURL, c.httpClient)
 	info, ok := debug.ReadBuildInfo()
 	if !ok {
@@ -1169,7 +1191,7 @@ func WithHostname(name string) StartOption {
 // WithTraceEnabled allows specifying whether tracing will be enabled
 func WithTraceEnabled(enabled bool) StartOption {
 	return func(c *config) {
-		c.enabled = newDynamicConfig("tracing_enabled", enabled, func(b bool) bool { return true }, equal[bool])
+		c.dynamic.enabled.update(enabled, telemetry.OriginCode)
 	}
 }
 

ddtrace/tracer/option_test.go

@@ -637,17 +637,19 @@ func TestTracerOptionsDefaults(t *testing.T) {
 			tracer := newTracer(WithAgentTimeout(2))
 			defer tracer.Stop()
 			c := tracer.config
-			assert.True(t, c.enabled.current)
-			assert.Equal(t, c.enabled.cfgOrigin, telemetry.OriginDefault)
+			assert.True(t, c.dynamic.enabled.current)
+			assert.True(t, knobs.GetScope(c.Scope, enabled))
+			assert.Equal(t, c.dynamic.enabled.cfgOrigin, telemetry.OriginDefault)
 		})
 
 		t.Run("override", func(t *testing.T) {
 			t.Setenv("DD_TRACE_ENABLED", "false")
 			tracer := newTracer(WithAgentTimeout(2))
 			defer tracer.Stop()
 			c := tracer.config
-			assert.False(t, c.enabled.current)
-			assert.Equal(t, c.enabled.cfgOrigin, telemetry.OriginEnvVar)
+			assert.False(t, c.dynamic.enabled.current)
+			assert.False(t, knobs.GetScope(c.Scope, enabled))
+			assert.Equal(t, c.dynamic.enabled.cfgOrigin, telemetry.OriginEnvVar)
 		})
 	})
 
@@ -1365,21 +1367,24 @@ func TestWithTraceEnabled(t *testing.T) {
 	t.Run("WithTraceEnabled", func(t *testing.T) {
 		assert := assert.New(t)
 		c := newConfig(WithTraceEnabled(false))
-		assert.False(c.enabled.current)
+		assert.False(c.dynamic.enabled.current)
+		assert.False(knobs.GetScope(c.Scope, enabled))
 	})
 
 	t.Run("otel-env", func(t *testing.T) {
 		assert := assert.New(t)
 		t.Setenv("OTEL_TRACES_EXPORTER", "none")
 		c := newConfig()
-		assert.False(c.enabled.current)
+		assert.False(c.dynamic.enabled.current)
+		assert.False(knobs.GetScope(c.Scope, enabled))
 	})
 
 	t.Run("dd-env", func(t *testing.T) {
 		assert := assert.New(t)
 		t.Setenv("DD_TRACE_ENABLED", "false")
 		c := newConfig()
-		assert.False(c.enabled.current)
+		assert.False(c.dynamic.enabled.current)
+		assert.False(knobs.GetScope(c.Scope, enabled))
 	})
 
 	t.Run("override-chain", func(t *testing.T) {
@@ -1388,10 +1393,12 @@ func TestWithTraceEnabled(t *testing.T) {
 		t.Setenv("OTEL_TRACES_EXPORTER", "none")
 		t.Setenv("DD_TRACE_ENABLED", "true")
 		c := newConfig()
-		assert.True(c.enabled.current)
+		assert.True(c.dynamic.enabled.current)
+		assert.True(knobs.GetScope(c.Scope, enabled))
 		// tracer option overrides dd env
 		c = newConfig(WithTraceEnabled(false))
-		assert.False(c.enabled.current)
+		assert.False(c.dynamic.enabled.current)
+		assert.False(knobs.GetScope(c.Scope, enabled))
 	})
 }
 

ddtrace/tracer/remote_config.go

@@ -181,7 +181,7 @@ func (t *tracer) onRemoteConfigUpdate(u remoteconfig.ProductUpdate) map[string]s
 		if updated {
 			telemConfigs = append(telemConfigs, t.config.globalTags.toTelemetry())
 		}
-		if !t.config.enabled.current {
+		if !t.config.dynamic.enabled.current {
 			log.Debug("APM Tracing is disabled. Restart the service to enable it.")
 		}
 		if len(telemConfigs) > 0 {
@@ -233,11 +233,11 @@ func (t *tracer) onRemoteConfigUpdate(u remoteconfig.ProductUpdate) map[string]s
 			telemConfigs = append(telemConfigs, t.config.globalTags.toTelemetry())
 		}
 		if c.LibConfig.Enabled != nil {
-			if t.config.enabled.current == true && *c.LibConfig.Enabled == false {
+			if t.config.dynamic.enabled.current == true && *c.LibConfig.Enabled == false {
 				log.Debug("Disabled APM Tracing through RC. Restart the service to enable it.")
-				t.config.enabled.handleRC(c.LibConfig.Enabled)
-				telemConfigs = append(telemConfigs, t.config.enabled.toTelemetry())
-			} else if t.config.enabled.current == false && *c.LibConfig.Enabled == true {
+				t.config.dynamic.enabled.handleRC(c.LibConfig.Enabled)
+				telemConfigs = append(telemConfigs, t.config.dynamic.enabled.toTelemetry())
+			} else if t.config.dynamic.enabled.current == false && *c.LibConfig.Enabled == true {
 				log.Debug("APM Tracing is disabled. Restart the service to enable it.")
 			}
 		}

ddtrace/tracer/remote_config_test.go

@@ -18,6 +18,7 @@ import (
 	"gopkg.in/DataDog/dd-trace-go.v1/internal/telemetry/telemetrytest"
 
 	"github.com/DataDog/datadog-agent/pkg/remoteconfig/state"
+	"github.com/darccio/knobs"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -395,7 +396,7 @@ func TestOnRemoteConfigUpdate(t *testing.T) {
 
 		applyStatus := tr.onRemoteConfigUpdate(input)
 		require.Equal(t, state.ApplyStateAcknowledged, applyStatus["path"].State)
-		require.Equal(t, false, tr.config.enabled.current)
+		require.Equal(t, false, tr.config.dynamic.enabled.current)
 		headers := TextMapCarrier{
 			traceparentHeader:      "00-12345678901234567890123456789012-1234567890123456-01",
 			tracestateHeader:       "dd=s:2;o:rum;t.usr.id:baz64~~",
@@ -417,7 +418,7 @@ func TestOnRemoteConfigUpdate(t *testing.T) {
 		input = remoteconfig.ProductUpdate{"path": nil}
 		applyStatus = tr.onRemoteConfigUpdate(input)
 		require.Equal(t, state.ApplyStateAcknowledged, applyStatus["path"].State)
-		require.Equal(t, false, tr.config.enabled.current)
+		require.Equal(t, false, knobs.GetScope(tr.config.Scope, enabled))
 
 		// turning tracing back explicitly is not allowed
 		input = remoteconfig.ProductUpdate{
@@ -427,7 +428,8 @@ func TestOnRemoteConfigUpdate(t *testing.T) {
 		}
 		applyStatus = tr.onRemoteConfigUpdate(input)
 		require.Equal(t, state.ApplyStateAcknowledged, applyStatus["path"].State)
-		require.Equal(t, false, tr.config.enabled.current)
+		require.Equal(t, false, tr.config.dynamic.enabled.current)
+		require.Equal(t, false, knobs.GetScope(tr.config.Scope, enabled))
 
 		telemetryClient.AssertNumberOfCalls(t, "ConfigChange", 1)
 	})

ddtrace/tracer/span.go

@@ -32,6 +32,7 @@ import (
 	"gopkg.in/DataDog/dd-trace-go.v1/internal/samplernames"
 	"gopkg.in/DataDog/dd-trace-go.v1/internal/traceprof"
 
+	"github.com/darccio/knobs"
 	"github.com/tinylib/msgp/msgp"
 	"golang.org/x/xerrors"
 
@@ -548,7 +549,7 @@ func (s *span) finish(finishTime int64) {
 
 	keep := true
 	if t, ok := internal.GetGlobalTracer().(*tracer); ok {
-		if !t.config.enabled.current {
+		if !knobs.GetScope(t.config.Scope, enabled) {
 			return
 		}
 		// we have an active tracer

ddtrace/tracer/telemetry.go

@@ -10,6 +10,8 @@ import (
 	"strings"
 
 	"gopkg.in/DataDog/dd-trace-go.v1/internal/telemetry"
+
+	"github.com/darccio/knobs"
 )
 
 var additionalConfigs []telemetry.Configuration
@@ -63,7 +65,7 @@ func startTelemetry(c *config) {
 		{Name: "trace_span_attribute_schema", Value: c.spanAttributeSchemaVersion},
 		{Name: "trace_peer_service_defaults_enabled", Value: c.peerServiceDefaultsEnabled},
 		{Name: "orchestrion_enabled", Value: c.orchestrionCfg.Enabled},
-		{Name: "trace_enabled", Value: c.enabled.current, Origin: c.enabled.cfgOrigin},
+		{Name: "trace_enabled", Value: knobs.GetScope(c.Scope, enabled), Origin: c.dynamic.enabled.cfgOrigin},
 		{Name: "trace_log_directory", Value: c.logDirectory},
 		c.traceSampleRate.toTelemetry(),
 		c.headerAsTags.toTelemetry(),

ddtrace/tracer/tracer.go

@@ -152,7 +152,7 @@ func Start(opts ...StartOption) {
 	}
 	defer telemetry.Time(telemetry.NamespaceGeneral, "init_time", nil, true)()
 	t := newTracer(opts...)
-	if !t.config.enabled.current {
+	if !knobs.GetScope(t.config.Scope, enabled) {
 		// TODO: instrumentation telemetry client won't get started
 		// if tracing is disabled, but we still want to capture this
 		// telemetry information. Will be fixed when the tracer and profiler
@@ -500,7 +500,7 @@ func (t *tracer) pushChunk(trace *chunk) {
 
 // StartSpan creates, starts, and returns a new Span with the given `operationName`.
 func (t *tracer) StartSpan(operationName string, options ...ddtrace.StartSpanOption) ddtrace.Span {
-	if !t.config.enabled.current {
+	if !knobs.GetScope(t.config.Scope, enabled) {
 		return internal.NoopSpan{}
 	}
 	var opts ddtrace.StartSpanConfig
@@ -716,7 +716,7 @@ func (t *tracer) Stop() {
 
 // Inject uses the configured or default TextMap Propagator.
 func (t *tracer) Inject(ctx ddtrace.SpanContext, carrier interface{}) error {
-	if !t.config.enabled.current {
+	if !knobs.GetScope(t.config.Scope, enabled) {
 		return nil
 	}
 	t.updateSampling(ctx)
@@ -755,7 +755,7 @@ func (t *tracer) updateSampling(ctx ddtrace.SpanContext) {
 
 // Extract uses the configured or default TextMap Propagator.
 func (t *tracer) Extract(carrier interface{}) (ddtrace.SpanContext, error) {
-	if !t.config.enabled.current {
+	if !knobs.GetScope(t.config.Scope, enabled) {
 		return internal.NoopSpanContext{}, nil
 	}
 	return t.config.propagator.Extract(carrier)