Add service.instance.id to mailroom telemetry resource

payjoin-mailroom/Cargo.toml

@@ -21,7 +21,7 @@ ws-bootstrap = ["dep:tokio-tungstenite", "dep:rustls"]
 _manual-tls = ["dep:axum-server", "dep:rustls"]
 acme = ["dep:tokio-rustls-acme", "dep:axum-server", "dep:rustls"]
 access-control = ["dep:flate2", "dep:ipnet", "dep:maxminddb", "dep:reqwest"]
-telemetry = ["dep:opentelemetry-otlp"]
+telemetry = ["dep:opentelemetry-otlp", "dep:uuid"]
 
 [dependencies]
 anyhow = "1.0.99"
@@ -82,6 +82,7 @@ tower-http = { version = "0.6.11", features = ["trace"] }
 tracing = "0.1.41"
 tracing-subscriber = { version = "0.3.19", features = ["env-filter", "json"] }
 unicode-segmentation = "=1.12.0"
+uuid = { version = "1.18.0", features = ["v4"], optional = true }
 
 # Pinned transitive dependencies that appear unused to cargo-machete
 [package.metadata.cargo-machete]

payjoin-mailroom/src/main.rs

@@ -36,14 +36,10 @@ fn init_tracing() -> Option<SdkMeterProvider> {
 
 #[cfg(feature = "telemetry")]
 fn init_tracing_with_telemetry(telemetry: &config::TelemetryConfig) -> SdkMeterProvider {
-    use opentelemetry::KeyValue;
     use opentelemetry_otlp::{WithExportConfig, WithHttpConfig};
-    use opentelemetry_sdk::Resource;
+    use payjoin_mailroom::metrics::build_telemetry_resource;
 
-    let resource = Resource::builder()
-        .with_service_name("payjoin-mailroom")
-        .with_attribute(KeyValue::new("operator.domain", telemetry.operator_domain.clone()))
-        .build();
+    let resource = build_telemetry_resource(&telemetry.operator_domain);
 
     let headers: std::collections::HashMap<String, String> =
         [("Authorization".to_string(), format!("Basic {}", telemetry.auth_token))].into();

payjoin-mailroom/src/metrics.rs

@@ -4,6 +4,16 @@ use std::fmt;
 use std::sync::{Arc, Mutex};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
+#[cfg(feature = "telemetry")]
+pub fn build_telemetry_resource(operator_domain: &str) -> opentelemetry_sdk::Resource {
+    use opentelemetry::KeyValue;
+    opentelemetry_sdk::Resource::builder()
+        .with_service_name("payjoin-mailroom")
+        .with_attribute(KeyValue::new("operator.domain", operator_domain.to_string()))
+        .with_attribute(KeyValue::new("service.instance.id", uuid::Uuid::new_v4().to_string()))
+        .build()
+}
+
 use hyperloglogplus::{HyperLogLog, HyperLogLogPlus};
 use opentelemetry::metrics::{Counter, MeterProvider, ObservableGauge, UpDownCounter};
 use opentelemetry::KeyValue;
@@ -337,6 +347,41 @@ impl Drop for InFlightGuard {
 #[cfg(test)]
 mod tests {
     use opentelemetry_sdk::metrics::data::{AggregatedMetrics, MetricData};
+
+    #[cfg(feature = "telemetry")]
+    #[test]
+    fn telemetry_resource_attributes() {
+        use opentelemetry::Key;
+
+        use super::build_telemetry_resource;
+
+        let r1 = build_telemetry_resource("example.com");
+
+        assert_eq!(
+            r1.get(&Key::from("service.name")),
+            Some(opentelemetry::Value::String("payjoin-mailroom".into())),
+            "service.name must be payjoin-mailroom"
+        );
+        assert_eq!(
+            r1.get(&Key::from("operator.domain")),
+            Some(opentelemetry::Value::String("example.com".into())),
+            "operator.domain must match configured value"
+        );
+
+        let id1 = r1
+            .get(&Key::from("service.instance.id"))
+            .expect("service.instance.id must be present")
+            .to_string();
+        assert!(!id1.is_empty(), "service.instance.id must not be empty");
+        uuid::Uuid::parse_str(&id1).expect("service.instance.id must parse as a UUID");
+
+        let r2 = build_telemetry_resource("example.com");
+        let id2 = r2
+            .get(&Key::from("service.instance.id"))
+            .expect("service.instance.id must be present in second resource")
+            .to_string();
+        assert_ne!(id1, id2, "service.instance.id must differ across constructions");
+    }
     use opentelemetry_sdk::metrics::{InMemoryMetricExporter, PeriodicReader, SdkMeterProvider};
 
     use super::*;