[SVLS-8757] Add instance enhanced metric in Azure Functions

crates/datadog-metrics-collector/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "datadog-metrics-collector"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+description = "Collector to read, compute, and submit enhanced metrics in Serverless environments"
+
+[dependencies]
+dogstatsd = { path = "../dogstatsd", default-features = true }
+tracing = { version = "0.1", default-features = false }
+libdd-common = { git = "https://github.com/DataDog/libdatadog", rev = "8c88979985154d6d97c0fc2ca9039682981eacad", default-features = false }

crates/datadog-metrics-collector/src/instance.rs

@@ -0,0 +1,100 @@
+// Copyright 2023-Present Datadog, Inc. https://www.datadoghq.com/
+// SPDX-License-Identifier: Apache-2.0
+
+//! Instance identity metric collector for Azure Functions.
+//!
+//! Submits `azure.functions.enhanced.instance` with value 1.0 on each
+//! collection tick, tagged with the instance identifier.
+
+use dogstatsd::aggregator::AggregatorHandle;
+use dogstatsd::metric::{Metric, MetricValue, SortedTags};
+use std::env;
+use tracing::{error, warn};
+
+const INSTANCE_METRIC: &str = "azure.functions.enhanced.instance";
+
+/// Resolves the instance ID from explicit values (used by tests).
+fn resolve_instance_id_from(
+    website_instance_id: Option<&str>,
+    website_pod_name: Option<&str>,
+    container_name: Option<&str>,
+) -> Option<String> {
+    website_instance_id
+        .or(website_pod_name)
+        .or(container_name)
+        .map(String::from)
+}
+
+/// Resolves the instance ID from environment variables.
+///
+/// Checks in order:
+/// 1. `WEBSITE_INSTANCE_ID` (Elastic Premium / Premium plans)
+/// 2. `WEBSITE_POD_NAME` (Flex Consumption / Consumption plans)
+/// 3. `CONTAINER_NAME` (Flex Consumption / Consumption plans)
+fn resolve_instance_id() -> Option<String> {
+    resolve_instance_id_from(
+        env::var("WEBSITE_INSTANCE_ID").ok().as_deref(),
+        env::var("WEBSITE_POD_NAME").ok().as_deref(),
+        env::var("CONTAINER_NAME").ok().as_deref(),
+    )
+}
+
+pub struct InstanceMetricsCollector {
+    aggregator: AggregatorHandle,
+    tags: Option<SortedTags>,
+}
+
+impl InstanceMetricsCollector {
+    /// Creates a new collector, returning `None` if no instance ID is found.
+    pub fn new(aggregator: AggregatorHandle, tags: Option<SortedTags>) -> Option<Self> {
+        let instance_id = resolve_instance_id();
+        let Some(instance_id) = instance_id else {
+            warn!("No instance ID found, instance metric will not be submitted");
+            return None;
+        };
+
+        // Precompute tags: enhanced metrics tags + instance tag
+        let instance_tag = format!("instance:{}", instance_id);
+        let tags = match tags {
+            Some(mut existing) => {
+                if let Ok(id_tag) = SortedTags::parse(&instance_tag) {
+                    existing.extend(&id_tag);
+                }
+                Some(existing)
+            }
+            None => SortedTags::parse(&instance_tag).ok(),
+        };
+
+        Some(Self { aggregator, tags })
+    }
+
+    pub fn collect_and_submit(&self) {
+        let metric = Metric::new(
+            INSTANCE_METRIC.into(),
+            MetricValue::gauge(1.0),
+            self.tags.clone(),
+            None,
+        );
+
+        if let Err(e) = self.aggregator.insert_batch(vec![metric]) {
+            error!("Failed to insert instance metric: {}", e);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_resolve_instance_id_falls_back_to_pod_name() {
+        let id = resolve_instance_id_from(None, Some("pod-xyz"), Some("container-123"));
+        assert_eq!(id, Some("pod-xyz".to_string()));
+    }
+
+    #[test]
+    fn test_resolve_instance_id_falls_back_to_container_name() {
+        let id = resolve_instance_id_from(None, None, Some("container-123"));
+        assert_eq!(id, Some("container-123".to_string()));
+    }
+}

crates/datadog-metrics-collector/src/lib.rs

@@ -0,0 +1,11 @@
+// Copyright 2023-Present Datadog, Inc. https://www.datadoghq.com/
+// SPDX-License-Identifier: Apache-2.0
+
+#![cfg_attr(not(test), deny(clippy::panic))]
+#![cfg_attr(not(test), deny(clippy::unwrap_used))]
+#![cfg_attr(not(test), deny(clippy::expect_used))]
+#![cfg_attr(not(test), deny(clippy::todo))]
+#![cfg_attr(not(test), deny(clippy::unimplemented))]
+
+pub mod instance;
+pub mod tags;

crates/datadog-metrics-collector/src/tags.rs

@@ -0,0 +1,55 @@
+// Copyright 2023-Present Datadog, Inc. https://www.datadoghq.com/
+// SPDX-License-Identifier: Apache-2.0
+
+//! Shared tag builder for enhanced metrics.
+//!
+//! Tags are attached to all enhanced metrics submitted by the metrics collector.
+
+use dogstatsd::metric::SortedTags;
+use libdd_common::azure_app_services;
+use std::env;
+
+/// Builds the common tags for all enhanced metrics.
+///
+/// Sources:
+/// - Azure metadata (resource_group, subscription_id, name) from libdd_common
+/// - Environment variables (region, plan_tier, service, env, version, serverless_compat_version)
+///
+/// The DogStatsD origin tag (e.g. `origin:azurefunction`) is added by the metrics aggregator,
+/// not here.
+pub fn build_enhanced_metrics_tags() -> Option<SortedTags> {
+    let mut tag_parts = Vec::new();
+
+    if let Some(aas_metadata) = &*azure_app_services::AAS_METADATA_FUNCTION {
+        let aas_tags = [
+            ("resource_group", aas_metadata.get_resource_group()),
+            ("subscription_id", aas_metadata.get_subscription_id()),
+            ("name", aas_metadata.get_site_name()),
+        ];
+        for (name, value) in aas_tags {
+            if value != "unknown" {
+                tag_parts.push(format!("{}:{}", name, value));
+            }
+        }
+    }
+
+    for (tag_name, env_var) in [
+        ("region", "REGION_NAME"),
+        ("plan_tier", "WEBSITE_SKU"),
+        ("service", "DD_SERVICE"),
+        ("env", "DD_ENV"),
+        ("version", "DD_VERSION"),
+        ("serverless_compat_version", "DD_SERVERLESS_COMPAT_VERSION"),
+    ] {
+        if let Ok(val) = env::var(env_var)
+            && !val.is_empty()
+        {
+            tag_parts.push(format!("{}:{}", tag_name, val));
+        }
+    }
+
+    if tag_parts.is_empty() {
+        return None;
+    }
+    SortedTags::parse(&tag_parts.join(",")).ok()
+}

crates/datadog-serverless-compat/Cargo.toml

@@ -11,6 +11,7 @@ windows-pipes = ["datadog-trace-agent/windows-pipes", "dogstatsd/windows-pipes"]
 
 [dependencies]
 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 = "8c88979985154d6d97c0fc2ca9039682981eacad" }
 datadog-fips = { path = "../datadog-fips", default-features = false }