chore(config/tracer): migrate traceProtocol

ddtrace/tracer/log.go

@@ -166,7 +166,7 @@ func logStartup(t *tracer) {
 		info.SampleRateLimit = fmt.Sprintf("%v", limit)
 	}
 	if !t.config.logToStdout {
-		if err := checkEndpoint(t.config.httpClient, t.config.transport.endpoint(), t.config.traceProtocol); err != nil {
+		if err := checkEndpoint(t.config.httpClient, t.config.transport.endpoint(), t.config.internalConfig.TraceProtocol()); err != nil {
 			info.AgentError = fmt.Sprintf("%s", err.Error())
 			log.Warn("DIAGNOSTICS Unable to reach agent intake: %s", err.Error())
 		}

ddtrace/tracer/option.go

@@ -334,9 +334,6 @@ type config struct {
 	// traceRateLimitPerSecond specifies the rate limit for traces.
 	traceRateLimitPerSecond float64
 
-	// traceProtocol specifies the trace protocol to use.
-	traceProtocol float64
-
 	// llmobs contains the LLM Observability config
 	llmobs llmobsconfig.Config
 
@@ -629,13 +626,11 @@ func newConfig(opts ...StartOption) (*config, error) {
 	// if using stdout or traces are disabled or we are in ci visibility agentless mode, agent is disabled
 	agentDisabled := c.logToStdout || !c.enabled.current || c.ciVisibilityAgentless
 	c.agent = loadAgentFeatures(agentDisabled, c.agentURL, c.httpClient)
-	if c.agent.v1ProtocolAvailable {
-		c.traceProtocol = traceProtocolV1
+	if c.internalConfig.V1ProtocolEnabled() && c.agent.v1ProtocolAvailable {
+		c.internalConfig.SetTraceProtocol(traceProtocolV1, internalconfig.OriginCalculated)
 		if t, ok := c.transport.(*httpTransport); ok {
 			t.traceURL = fmt.Sprintf("%s%s", c.agentURL.String(), tracesAPIPathV1)
 		}
-	} else {
-		c.traceProtocol = traceProtocolV04
 	}
 
 	info, ok := debug.ReadBuildInfo()
@@ -806,7 +801,6 @@ type agentFeatures struct {
 
 	// evpProxyV2 reports if the trace-agent can receive payloads on the /evp_proxy/v2 endpoint.
 	evpProxyV2 bool
-
 	// v1ProtocolAvailable reports whether the trace-agent and tracer are configured to use the v1 protocol.
 	v1ProtocolAvailable bool
 }
@@ -868,10 +862,7 @@ func loadAgentFeatures(agentDisabled bool, agentURL *url.URL, httpClient *http.C
 		case "/evp_proxy/v2/":
 			features.evpProxyV2 = true
 		case "/v1.0/traces":
-			// Set the trace protocol to use.
-			if internal.BoolEnv("DD_TRACE_V1_PAYLOAD_FORMAT_ENABLED", false) {
-				features.v1ProtocolAvailable = true
-			}
+			features.v1ProtocolAvailable = true
 		}
 	}
 	features.featureFlags = make(map[string]struct{}, len(info.FeatureFlags))

ddtrace/tracer/writer.go

@@ -98,7 +98,7 @@ func (h *agentTraceWriter) stop() {
 
 // newPayload returns a new payload based on the trace protocol.
 func (h *agentTraceWriter) newPayload() payload {
-	return newPayload(h.config.traceProtocol)
+	return newPayload(h.config.internalConfig.TraceProtocol())
 }
 
 // flush will push any currently buffered traces to the server.

internal/config/config.go

@@ -30,6 +30,12 @@ const (
 	OriginCalculated = telemetry.OriginCalculated
 )
 
+// Supported trace protocols.
+const (
+	traceProtocolV04 = 0.4 // v0.4 (default)
+	traceProtocolV1  = 1.0 // v1.0
+)
+
 // Config represents global configuration properties.
 // Config instances should be obtained via Get() which always returns a non-nil value.
 // Methods on Config assume a non-nil receiver and will panic if called on nil.
@@ -63,6 +69,10 @@ type Config struct {
 	ciVisibilityAgentless         bool
 	logDirectory                  string
 	traceRateLimitPerSecond       float64
+	// traceProtocol specifies the trace protocol to use.
+	traceProtocol float64
+	// v1ProtocolEnabled reports whether the trace-agent and tracer are configured to use the v1 protocol.
+	v1ProtocolEnabled bool
 }
 
 // loadConfig initializes and returns a new config by reading from all configured sources.
@@ -98,6 +108,8 @@ func loadConfig() *Config {
 	cfg.ciVisibilityAgentless = provider.getBool("DD_CIVISIBILITY_AGENTLESS_ENABLED", false)
 	cfg.logDirectory = provider.getString("DD_TRACE_LOG_DIRECTORY", "")
 	cfg.traceRateLimitPerSecond = provider.getFloat("DD_TRACE_RATE_LIMIT", 0.0)
+	cfg.v1ProtocolEnabled = provider.getBool("DD_TRACE_V1_PAYLOAD_FORMAT_ENABLED", false)
+	cfg.traceProtocol = traceProtocolV04
 
 	return cfg
 }
@@ -134,3 +146,29 @@ func (c *Config) SetDebug(enabled bool, origin telemetry.Origin) {
 	c.debug = enabled
 	telemetry.RegisterAppConfig("DD_TRACE_DEBUG", enabled, origin)
 }
+
+func (c *Config) V1ProtocolEnabled() bool {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	return c.v1ProtocolEnabled
+}
+
+func (c *Config) SetV1ProtocolEnabled(enabled bool, origin telemetry.Origin) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.v1ProtocolEnabled = enabled
+	telemetry.RegisterAppConfig("DD_TRACE_V1_PAYLOAD_FORMAT_ENABLED", enabled, origin)
+}
+
+func (c *Config) TraceProtocol() float64 {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	return c.traceProtocol
+}
+
+func (c *Config) SetTraceProtocol(protocol float64, origin telemetry.Origin) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.traceProtocol = protocol
+	// TODO: Report telemetry?
+}