feat(fake_data_generator): Add per-record variance to static log generation

rust/otap-dataflow/crates/core-nodes/src/receivers/fake_data_generator/config.rs

@@ -155,8 +155,10 @@ pub struct TrafficConfig {
     log_weight: u32,
 
     /// Target size of each log record body in bytes (Static data source only).
-    /// When set, generates a log body string of approximately this size.
-    /// When unset, uses the default hardcoded body ("Order processed successfully").
+    /// When set, pre-generates a pool of 50 distinct body strings of this size;
+    /// records cycle through the pool for realistic dictionary cardinality.
+    /// When 0, the body is omitted entirely.
+    /// When unset, cycles through ~50 default log message templates.
     #[serde(default)]
     log_body_size_bytes: Option<usize>,
 
@@ -165,6 +167,11 @@ pub struct TrafficConfig {
     /// When unset, uses the default 2 attributes (thread.id, thread.name).
     #[serde(default)]
     num_log_attributes: Option<usize>,
+
+    /// When true, each log record gets a unique random trace_id and span_id,
+    /// matching real log-to-trace correlation and adding per-record entropy.
+    #[serde(default)]
+    use_trace_context: bool,
 }
 
 impl Config {
@@ -282,6 +289,7 @@ impl TrafficConfig {
             log_weight,
             log_body_size_bytes: None,
             num_log_attributes: None,
+            use_trace_context: false,
         }
     }
 
@@ -359,6 +367,12 @@ impl TrafficConfig {
     pub const fn num_log_attributes(&self) -> Option<usize> {
         self.num_log_attributes
     }
+
+    /// Returns whether log records should include trace_id and span_id.
+    #[must_use]
+    pub const fn use_trace_context(&self) -> bool {
+        self.use_trace_context
+    }
 }
 
 const fn default_signals_per_second() -> Option<usize> {

rust/otap-dataflow/crates/core-nodes/src/receivers/fake_data_generator/mod.rs

@@ -118,6 +118,8 @@ enum SignalGenerator {
         log_body_size_bytes: Option<usize>,
         /// Number of log attributes (None = default attributes)
         num_log_attributes: Option<usize>,
+        /// Whether to populate trace_id/span_id on log records
+        use_trace_context: bool,
     },
 }
 
@@ -172,11 +174,13 @@ impl SignalGenerator {
             SignalGenerator::Static {
                 log_body_size_bytes,
                 num_log_attributes,
+                use_trace_context,
                 ..
             } => OtlpProtoMessage::Logs(static_signal::static_otlp_logs_with_config(
                 count,
                 *log_body_size_bytes,
                 *num_log_attributes,
+                *use_trace_context,
                 self.attrs_for_batch(batch_index),
             )),
         }
@@ -300,6 +304,7 @@ impl local::Receiver<OtapPdata> for FakeGeneratorReceiver {
                     rotation,
                     log_body_size_bytes: traffic_config.log_body_size_bytes(),
                     num_log_attributes: traffic_config.num_log_attributes(),
+                    use_trace_context: traffic_config.use_trace_context(),
                 }
             }
         };
@@ -1364,6 +1369,7 @@ mod tests {
             rotation,
             log_body_size_bytes: None,
             num_log_attributes: None,
+            use_trace_context: false,
         };
 
         // attrs_for_batch should rotate through the two sets
@@ -1417,6 +1423,7 @@ mod tests {
             rotation: vec![],
             log_body_size_bytes: None,
             num_log_attributes: None,
+            use_trace_context: false,
         };
         assert!(generator.attrs_for_batch(0).is_none());
         assert!(generator.attrs_for_batch(1).is_none());