feat(trace): add SQLObfuscationMode in /info APMSP-2764 (#48857)

This config field is needed for CSS obfuscation. In fact this is the only needed obfuscation config field AFAIK.

### What does this PR do?
- adds a "sql_obfuscation_mode" field to /info endpoint for using it when obfuscating stats in libraries.

### Motivation
- finish [integrating obfuscation to the trace exporter](DataDog/libdatadog#1819)

### Describe how you validated your changes
- [x] unit test
- [x] system test

### Additional Notes


Co-authored-by: oscar.ledauphin <oscar.ledauphin@datadoghq.com>

Author: Eldolfin

pkg/trace/api/info.go

@@ -41,6 +41,7 @@ type reducedObfuscationConfig struct {
 	Mongo                bool                      `json:"mongo"`
 	SQLExecPlan          bool                      `json:"sql_exec_plan"`
 	SQLExecPlanNormalize bool                      `json:"sql_exec_plan_normalize"`
+	SQLObfuscationMode   obfuscate.ObfuscationMode `json:"sql_obfuscation_mode"`
 	HTTP                 obfuscate.HTTPConfig      `json:"http"`
 	RemoveStackTraces    bool                      `json:"remove_stack_traces"`
 	Redis                obfuscate.RedisConfig     `json:"redis"`
@@ -87,6 +88,7 @@ func (r *HTTPReceiver) makeInfoHandler() (hash string, handler http.HandlerFunc)
 		oconf.Mongo = o.Mongo.Enabled
 		oconf.SQLExecPlan = o.SQLExecPlan.Enabled
 		oconf.SQLExecPlanNormalize = o.SQLExecPlanNormalize.Enabled
+		oconf.SQLObfuscationMode = r.conf.EffectiveSQLObfuscationMode()
 		oconf.HTTP = o.HTTP
 		oconf.RemoveStackTraces = o.RemoveStackTraces
 		oconf.Redis = o.Redis

pkg/trace/api/info_test.go

@@ -349,6 +349,7 @@ func TestInfoHandler(t *testing.T) {
 				"mongo":                   nil,
 				"sql_exec_plan":           nil,
 				"sql_exec_plan_normalize": nil,
+				"sql_obfuscation_mode":    nil,
 				"http": map[string]any{
 					"remove_query_string": nil,
 					"remove_path_digits":  nil,

pkg/trace/config/config.go

@@ -152,6 +152,13 @@ func obfuscationMode(conf *AgentConfig, sqllexerEnabled bool) obfuscate.Obfuscat
 	return ""
 }
 
+// EffectiveSQLObfuscationMode returns the SQL obfuscation mode the agent
+// actually uses at runtime. When SQLObfuscationMode is not explicitly set,
+// the mode is derived from feature flags (e.g. sqllexer → obfuscate_only).
+func (c *AgentConfig) EffectiveSQLObfuscationMode() obfuscate.ObfuscationMode {
+	return obfuscationMode(c, c.HasFeature("sqllexer"))
+}
+
 // Export returns an obfuscate.Config matching o.
 func (o *ObfuscationConfig) Export(conf *AgentConfig) obfuscate.Config {
 	return obfuscate.Config{
@@ -160,7 +167,7 @@ func (o *ObfuscationConfig) Export(conf *AgentConfig) obfuscate.Config {
 			ReplaceDigits:    conf.HasFeature("quantize_sql_tables") || conf.HasFeature("replace_sql_digits"),
 			KeepSQLAlias:     conf.HasFeature("keep_sql_alias"),
 			DollarQuotedFunc: conf.HasFeature("dollar_quoted_func"),
-			ObfuscationMode:  obfuscationMode(conf, conf.HasFeature("sqllexer")),
+			ObfuscationMode:  conf.EffectiveSQLObfuscationMode(),
 		},
 		ES:                   o.ES,
 		OpenSearch:           o.OpenSearch,

pkg/trace/config/config_test.go

@@ -155,6 +155,25 @@ func TestSQLObfuscationMode(t *testing.T) {
 	})
 }
 
+func TestEffectiveSQLObfuscationMode(t *testing.T) {
+	t.Run("sqllexer_enabled_no_explicit_mode", func(t *testing.T) {
+		cfg := New()
+		cfg.Features = map[string]struct{}{"sqllexer": {}}
+		// SQLObfuscationMode is empty; effective mode must be obfuscate_only
+		assert.Equal(t, obfuscate.ObfuscateOnly, cfg.EffectiveSQLObfuscationMode())
+	})
+	t.Run("explicit_mode_takes_precedence", func(t *testing.T) {
+		cfg := New()
+		cfg.Features = map[string]struct{}{"sqllexer": {}}
+		cfg.SQLObfuscationMode = string(obfuscate.ObfuscateAndNormalize)
+		assert.Equal(t, obfuscate.ObfuscateAndNormalize, cfg.EffectiveSQLObfuscationMode())
+	})
+	t.Run("no_sqllexer_no_explicit_mode", func(t *testing.T) {
+		cfg := New()
+		assert.Equal(t, obfuscate.ObfuscationMode(""), cfg.EffectiveSQLObfuscationMode())
+	})
+}
+
 func TestInECSManagedInstancesSidecar(t *testing.T) {
 	t.Setenv("DD_ECS_DEPLOYMENT_MODE", "sidecar")
 	t.Setenv("AWS_EXECUTION_ENV", "AWS_ECS_MANAGED_INSTANCES")