feat: implement implement additional metric tags for trace stats

crates/datadog-agent-config/Cargo.toml

@@ -6,8 +6,8 @@ license.workspace = true
 
 [dependencies]
 figment = { version = "0.10", default-features = false, features = ["yaml", "env"] }
-libdd-trace-obfuscation = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03", default-features = false }
-libdd-trace-utils = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03", default-features = false }
+libdd-trace-obfuscation = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4", default-features = false }
+libdd-trace-utils = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4", default-features = false }
 log = { version = "0.4", default-features = false }
 serde = { version = "1.0", default-features = false, features = ["derive"] }
 serde-aux = { version = "4.7", default-features = false }

crates/datadog-metrics-collector/Cargo.toml

@@ -8,7 +8,7 @@ description = "Collector to read, compute, and submit enhanced metrics in Server
 [dependencies]
 dogstatsd = { path = "../dogstatsd", default-features = true }
 tracing = { version = "0.1", default-features = false }
-libdd-common = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03", default-features = false }
+libdd-common = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4", default-features = false }
 
 [target.'cfg(windows)'.dependencies]
 windows-sys = { version = "0.61", features = ["Win32_System_JobObjects"], optional = true, default-features = false }

crates/datadog-serverless-compat/Cargo.toml

@@ -14,7 +14,7 @@ windows-enhanced-metrics = ["datadog-metrics-collector/windows-enhanced-metrics"
 datadog-logs-agent = { path = "../datadog-logs-agent" }
 datadog-metrics-collector = { path = "../datadog-metrics-collector" }
 datadog-trace-agent = { path = "../datadog-trace-agent" }
-libdd-trace-utils = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03" }
+libdd-trace-utils = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4" }
 datadog-fips = { path = "../datadog-fips", default-features = false }
 dogstatsd = { path = "../dogstatsd", default-features = true }
 reqwest = { version = "0.12.4", default-features = false }

crates/datadog-trace-agent/Cargo.toml

@@ -25,16 +25,16 @@ tracing = { version = "0.1", default-features = false }
 serde = { version = "1.0.145", features = ["derive"] }
 serde_json = "1.0"
 thiserror = { version = "1.0.58", default-features = false }
-libdd-capabilities = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03" }
-libdd-capabilities-impl = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03" }
-libdd-common = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03" }
-libdd-library-config = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03" }
-libdd-trace-protobuf = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03" }
-libdd-trace-stats = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03" }
-libdd-trace-utils = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03", features = [
+libdd-capabilities = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4" }
+libdd-capabilities-impl = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4" }
+libdd-common = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4" }
+libdd-library-config = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4" }
+libdd-trace-protobuf = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4" }
+libdd-trace-stats = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4" }
+libdd-trace-utils = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4", features = [
     "mini_agent",
 ] }
-libdd-trace-obfuscation = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03" }
+libdd-trace-obfuscation = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4" }
 datadog-fips = { path = "../datadog-fips" }
 reqwest = { version = "0.12.23", features = [
     "json",
@@ -49,6 +49,6 @@ serial_test = "2.0.0"
 duplicate = "2.0.1"
 temp-env = "0.3.6"
 tempfile = "3.3.0"
-libdd-trace-utils = { git = "https://github.com/DataDog/libdatadog", rev = "48da0d82cb32b43d4cdece35b794c9bcbc275a03", features = [
+libdd-trace-utils = { git = "https://github.com/DataDog/libdatadog", rev = "fc99d327bb54ca04a7c28b67117f546b11ea48a4", features = [
     "test-utils",
 ] }

crates/datadog-trace-agent/src/config.rs

@@ -115,6 +115,14 @@ pub struct Config {
     pub proxy_url: Option<String>,
     pub env: String,
     pub peer_tags: Vec<String>,
+    /// Gates additional_metric_tags and related config.
+    pub experimental_features_enabled: bool,
+    /// Tag keys extracted from spans and used as additional aggregation dimensions in stats.
+    /// Only populated when experimental_features_enabled is true.
+    pub additional_metric_tags: Vec<String>,
+    /// Configures the per-bucket cardinality limit for additional_metric_tags stat entries.
+    /// Only populated when experimental_features_enabled is true.
+    pub additional_metric_tags_cardinality_limit: Option<usize>,
     /// Whether the agent should compute trace stats
     pub agent_stats_computation_enabled: bool,
 }
@@ -216,6 +224,10 @@ impl Config {
             Tags::new()
         };
 
+        let experimental_features_enabled = env::var("DD_TRACE_EXPERIMENTAL_FEATURES_ENABLED")
+            .map(|val| val.to_lowercase() == "true")
+            .unwrap_or(false);
+
         #[allow(clippy::unwrap_used)]
         Ok(Config {
             app_name: Some(app_name),
@@ -262,6 +274,24 @@ impl Config {
             tags,
             env: env::var("DD_ENV").unwrap_or_else(|_| "none".to_string()),
             peer_tags: peer_tag_keys()?,
+            experimental_features_enabled,
+            additional_metric_tags: if experimental_features_enabled {
+                env::var("DD_TRACE_STATS_ADDITIONAL_TAGS")
+                    .ok()
+                    .filter(|s| !s.is_empty())
+                    .map(|s| s.split(',').map(str::to_owned).collect())
+                    .unwrap_or_default()
+            } else {
+                vec![]
+            },
+            additional_metric_tags_cardinality_limit: if experimental_features_enabled {
+                env::var("DD_TRACE_STATS_ADDITIONAL_TAGS_CARDINALITY_LIMIT")
+                    .ok()
+                    .and_then(|s| s.parse::<usize>().ok())
+                    .filter(|&n| n > 0)
+            } else {
+                None
+            },
             agent_stats_computation_enabled: env::var("DD_AGENT_STATS_COMPUTATION_ENABLED")
                 .map(|val| val.to_lowercase() == "true")
                 .unwrap_or(false),
@@ -745,6 +775,46 @@ mod tests {
             },
         );
     }
+
+    #[test]
+    #[serial]
+    fn test_additional_metric_tags_gated_by_experimental_flag() {
+        let base_vars = [
+            ("DD_API_KEY", Some("_not_a_real_key_")),
+            ("K_SERVICE", Some("function_name")),
+            ("FUNCTION_TARGET", Some("function_target")),
+            ("DD_TRACE_STATS_ADDITIONAL_TAGS", Some("region,tenant_id")),
+        ];
+
+        temp_env::with_vars(
+            base_vars
+                .iter()
+                .cloned()
+                .chain([("DD_TRACE_EXPERIMENTAL_FEATURES_ENABLED", Some("false"))])
+                .collect::<Vec<_>>(),
+            || {
+                let config = config::Config::new().unwrap();
+                assert!(!config.experimental_features_enabled);
+                assert!(config.additional_metric_tags.is_empty());
+            },
+        );
+
+        temp_env::with_vars(
+            base_vars
+                .iter()
+                .cloned()
+                .chain([("DD_TRACE_EXPERIMENTAL_FEATURES_ENABLED", Some("true"))])
+                .collect::<Vec<_>>(),
+            || {
+                let config = config::Config::new().unwrap();
+                assert!(config.experimental_features_enabled);
+                assert_eq!(
+                    config.additional_metric_tags,
+                    vec!["region".to_string(), "tenant_id".to_string()]
+                );
+            },
+        );
+    }
 }
 
 /// Test helpers for creating Config instances in tests
@@ -782,6 +852,9 @@ pub mod test_helpers {
             proxy_url: None,
             env: "none".to_string(),
             peer_tags: peer_tag_keys().unwrap(),
+            experimental_features_enabled: false,
+            additional_metric_tags: vec![],
+            additional_metric_tags_cardinality_limit: None,
             agent_stats_computation_enabled: false,
         }
     }

crates/datadog-trace-agent/src/stats_concentrator_service.rs

@@ -81,16 +81,25 @@ impl StatsConcentratorService {
         (service, handle)
     }
 
-    fn new_span_concentrator(peer_tags: Vec<String>) -> SpanConcentrator {
-        SpanConcentrator::new(
+    fn new_span_concentrator(
+        peer_tags: Vec<String>,
+        additional_metric_tags: Vec<String>,
+        additional_metric_tags_cardinality_limit: Option<usize>,
+    ) -> SpanConcentrator {
+        let mut concentrator = SpanConcentrator::new(
             Duration::from_nanos(BUCKET_DURATION_NS),
             SystemTime::now(),
             SPAN_KINDS_STATS_COMPUTED
                 .iter()
                 .map(|s| s.to_string())
                 .collect(),
             peer_tags,
-        )
+            additional_metric_tags,
+        );
+        if let Some(limit) = additional_metric_tags_cardinality_limit {
+            concentrator.set_additional_metric_tags_cardinality_limit(limit);
+        }
+        concentrator
     }
 
     pub async fn run(mut self) {
@@ -106,7 +115,13 @@ impl StatsConcentratorService {
                     let concentrator = self
                         .concentrators
                         .entry(Arc::clone(&metadata))
-                        .or_insert_with(|| Self::new_span_concentrator(config.peer_tags.clone()));
+                        .or_insert_with(|| {
+                            Self::new_span_concentrator(
+                                config.peer_tags.clone(),
+                                config.additional_metric_tags.clone(),
+                                config.additional_metric_tags_cardinality_limit,
+                            )
+                        });
 
                     for span in &chunk.spans {
                         concentrator.add_span(span);

crates/datadog-trace-agent/src/trace_processor.rs

@@ -285,6 +285,9 @@ mod tests {
             tags: Tags::from_env_string("env:test,service:my-service"),
             env: "test-env".to_string(),
             peer_tags: peer_tag_keys().unwrap(),
+            experimental_features_enabled: false,
+            additional_metric_tags: vec![],
+            additional_metric_tags_cardinality_limit: None,
             agent_stats_computation_enabled: false,
         }
     }