[APMSVLS-464][APMSVLS-463] fix: Configure span kind and peer tag stats

bottlecap/src/traces/stats_concentrator_service.rs

@@ -12,6 +12,66 @@ use tracing::error;
 const S_TO_NS: u64 = 1_000_000_000;
 const BUCKET_DURATION_NS: u64 = 10 * S_TO_NS; // 10 seconds
 
+/// Span kinds eligible for stats computation, matching the Go agent's default
+/// `ComputeStatsBySpanKind: true` behavior.
+/// Reference: `datadog-agent/pkg/trace/stats/span_concentrator.go` (`KindsComputed`)
+///
+/// TODO: Move to datadog-agent-config in serverless-components so both bottlecap and
+/// serverless-compat can share this list.
+const STATS_ELIGIBLE_SPAN_KINDS: [&str; 4] = ["client", "consumer", "producer", "server"];
+
+/// Default peer tag keys for stats aggregation, matching the Go agent's `basePeerTags`
+/// derived from pkg/trace/semantics/mappings.json via the 16 peer tag concepts.
+/// Reference: `datadog-agent/pkg/trace/config/peer_tags.go` (`peerTagConcepts` + `basePeerTags`)
+///
+/// TODO: Move to datadog-agent-config in serverless-components so both bottlecap and
+/// serverless-compat can share this list.
+const DEFAULT_PEER_TAG_KEYS: [&str; 43] = [
+    "_dd.base_service",
+    "active_record.db.vendor",
+    "amqp.destination",
+    "amqp.exchange",
+    "amqp.queue",
+    "aws.queue.name",
+    "aws.s3.bucket",
+    "bucketname",
+    "cassandra.keyspace",
+    "db.cassandra.contact.points",
+    "db.couchbase.seed.nodes",
+    "db.hostname",
+    "db.instance",
+    "db.name",
+    "db.namespace",
+    "db.system",
+    "db.type",
+    "dns.hostname",
+    "grpc.host",
+    "hostname",
+    "http.host",
+    "http.server_name",
+    "messaging.destination",
+    "messaging.destination.name",
+    "messaging.kafka.bootstrap.servers",
+    "messaging.rabbitmq.exchange",
+    "messaging.system",
+    "mongodb.db",
+    "msmq.queue.path",
+    "net.peer.name",
+    "network.destination.ip",
+    "network.destination.name",
+    "out.host",
+    "peer.hostname",
+    "peer.service",
+    "queuename",
+    "rpc.service",
+    "rpc.system",
+    "sequel.db.vendor",
+    "server.address",
+    "streamname",
+    "tablename",
+    "topicname",
+];
+
 #[derive(Debug, thiserror::Error)]
 pub enum StatsError {
     #[error("Failed to send command to concentrator: {0}")]
@@ -113,12 +173,17 @@ impl StatsConcentratorService {
     pub fn new(config: Arc<Config>) -> (Self, StatsConcentratorHandle) {
         let (tx, rx) = mpsc::unbounded_channel();
         let handle = StatsConcentratorHandle::new(tx);
-        // TODO: set span_kinds_stats_computed and peer_tag_keys
         let concentrator = SpanConcentrator::new(
             Duration::from_nanos(BUCKET_DURATION_NS),
             SystemTime::now(),
-            vec![],
-            vec![],
+            STATS_ELIGIBLE_SPAN_KINDS
+                .iter()
+                .map(ToString::to_string)
+                .collect(),
+            DEFAULT_PEER_TAG_KEYS
+                .iter()
+                .map(ToString::to_string)
+                .collect(),
         );
         let service: StatsConcentratorService = Self {
             concentrator,
@@ -192,3 +257,121 @@ impl StatsConcentratorService {
         }
     }
 }
+
+#[cfg(test)]
+#[allow(clippy::unwrap_used)]
+mod tests {
+    use super::*;
+    use std::collections::HashMap;
+
+    /// Create a `pb::Span` with the given meta tags and metrics.
+    /// The span is non-root (`parent_id=1`) and not measured, so it will only be
+    /// eligible for stats if `span_kinds_stats_computed` includes its `span.kind`.
+    fn create_span_kind_span(span_kind: &str, meta: Vec<(&str, &str)>) -> pb::Span {
+        let now_ns = SystemTime::now()
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .unwrap()
+            .as_nanos() as i64;
+        let mut meta_map: HashMap<String, String> = meta
+            .into_iter()
+            .map(|(k, v)| (k.to_string(), v.to_string()))
+            .collect();
+        meta_map.insert("span.kind".to_string(), span_kind.to_string());
+        pb::Span {
+            service: "test-service".to_string(),
+            name: "test-op".to_string(),
+            resource: "test-resource".to_string(),
+            trace_id: 1,
+            span_id: 2,
+            parent_id: 1, // non-root
+            start: now_ns,
+            duration: 100,
+            error: 0,
+            r#type: "web".to_string(),
+            meta: meta_map,
+            metrics: HashMap::new(), // no _top_level, no _dd.measured
+            meta_struct: HashMap::new(),
+            span_links: vec![],
+            span_events: vec![],
+        }
+    }
+
+    /// A non-root, non-measured span with `span.kind`="client" should produce stats
+    /// when `ComputeStatsBySpanKind` is enabled (i.e. `span_kinds_stats_computed` is
+    /// populated). With the current empty vec, this span is silently dropped.
+    #[tokio::test]
+    async fn test_span_kind_stats_computed() {
+        let config = Arc::new(Config::default());
+        let (service, handle) = StatsConcentratorService::new(config);
+        tokio::spawn(service.run());
+
+        let span = create_span_kind_span("client", vec![]);
+        handle.add(&span).unwrap();
+
+        let result = handle.flush(true).await.unwrap();
+
+        assert!(
+            result.is_some(),
+            "Expected stats for a client span, but got None. \
+             span.kind-based eligibility is not working."
+        );
+        let payload = result.unwrap();
+        let all_stats: Vec<_> = payload.stats.iter().flat_map(|b| &b.stats).collect();
+        assert!(
+            !all_stats.is_empty(),
+            "Expected at least one grouped stats entry for the client span."
+        );
+        let client_stats: Vec<_> = all_stats
+            .iter()
+            .filter(|s| s.span_kind == "client")
+            .collect();
+        assert!(
+            !client_stats.is_empty(),
+            "Expected a stats entry with span_kind='client'."
+        );
+    }
+
+    /// A client span with peer tag meta keys (`db.instance`, `db.system`) should produce
+    /// stats with non-empty `peer_tags` when `peer_tag_keys` is configured. With the
+    /// current empty vec, `peer_tags` in the output will always be empty.
+    #[tokio::test]
+    async fn test_peer_tags_populated() {
+        let config = Arc::new(Config::default());
+        let (service, handle) = StatsConcentratorService::new(config);
+        tokio::spawn(service.run());
+
+        let span = create_span_kind_span(
+            "client",
+            vec![("db.instance", "i-1234"), ("db.system", "postgres")],
+        );
+        handle.add(&span).unwrap();
+
+        let result = handle.flush(true).await.unwrap();
+
+        assert!(
+            result.is_some(),
+            "Expected stats for a client span with peer tags, but got None. \
+             span.kind-based eligibility is not working."
+        );
+        let payload = result.unwrap();
+        let all_stats: Vec<_> = payload.stats.iter().flat_map(|b| &b.stats).collect();
+        let stats_with_peer_tags: Vec<_> = all_stats
+            .iter()
+            .filter(|s| !s.peer_tags.is_empty())
+            .collect();
+        assert!(
+            !stats_with_peer_tags.is_empty(),
+            "Expected at least one stats entry with non-empty peer_tags, \
+             but all entries have empty peer_tags."
+        );
+        let peer_tags = &stats_with_peer_tags[0].peer_tags;
+        assert!(
+            peer_tags.iter().any(|t| t.starts_with("db.instance:")),
+            "Expected peer_tags to contain db.instance, got: {peer_tags:?}"
+        );
+        assert!(
+            peer_tags.iter().any(|t| t.starts_with("db.system:")),
+            "Expected peer_tags to contain db.system, got: {peer_tags:?}"
+        );
+    }
+}