Opentelemetry initializer

loco-extras/Cargo.toml

@@ -20,6 +20,13 @@ tower = { workspace = true, optional = true }
 tower-http = { workspace = true, optional = true, features = [
   "normalize-path",
 ] }
+opentelemetry = { version = "0.22" , optional = true}
+opentelemetry-otlp = { version = "0.15", optional = true, features = ["grpc-tonic"] }
+axum-tracing-opentelemetry = { version = "0.18", optional = true }
+init-tracing-opentelemetry = { version = "0.18", optional = true , features = ["otlp", "tracing_subscriber_ext"] }
+tracing-opentelemetry-instrumentation-sdk = { version = "0.18", optional = true }
+tracing-subscriber = { version = "0.3.18", optional = true , features = ["env-filter", "json"] }
+tracing = { version = "0.1.40", optional = true }
 
 [dependencies.loco-rs]
 path = "../"
@@ -34,9 +41,12 @@ full = [
   "initializer-extra-db",
   "initializer-multi-db",
   "initializer-normalize-path",
+  "initializer-opentelemetry",
 ]
 
 initializer-prometheus = ["dep:axum-prometheus"]
 initializer-extra-db = []
 initializer-multi-db = ["dep:serde_json"]
 initializer-normalize-path = ["dep:tower", "dep:tower-http"]
+initializer-opentelemetry = ["dep:opentelemetry","dep:opentelemetry-otlp","dep:axum-tracing-opentelemetry",
+    "dep:init-tracing-opentelemetry", "dep:tracing-opentelemetry-instrumentation-sdk","dep:tracing-subscriber","dep:tracing"]

loco-extras/src/initializers/mod.rs

@@ -67,3 +67,5 @@ pub mod multi_db;
 pub mod normalize_path;
 #[cfg(feature = "initializer-prometheus")]
 pub mod prometheus;
+#[cfg(feature = "initializer-opentelemetry")]
+pub mod opentelemetry;

loco-extras/src/initializers/opentelemetry/README.md

@@ -0,0 +1,11 @@
+# Opentelemetry Initializer
+
+This initializer is responsible for initializing tracing with opentelemetry and adding it as a middleware in axum. 
+
+Because opentelemetry tracing initializer is not compatible with loco's default tracing initialization we must turn off the default logging.
+
+````
+fn init_logger(_config: &config::Config, _env: &Environment) -> Result<bool> {
+    Ok(true)
+}
+````

loco-extras/src/initializers/opentelemetry/mod.rs

@@ -0,0 +1,30 @@
+use axum::{async_trait, Extension, Router as AxumRouter};
+use axum_tracing_opentelemetry::middleware::{OtelAxumLayer, OtelInResponseLayer};
+use loco_rs::{app::{AppContext, Initializer}, Error, Result};
+
+pub struct OpenTelemetryInitializer;
+
+#[async_trait]
+impl Initializer for OpenTelemetryInitializer {
+    fn name(&self) -> String {
+        "opentelemetry".to_string()
+    }
+
+    async fn before_run(&self, _app_context: &AppContext) -> Result<()> {
+        match init_tracing_opentelemetry::tracing_subscriber_ext::init_subscribers() {
+            Ok(_) => Ok(()),
+            Err(e) => {
+                tracing::error!("Failed to initialize opentelemetry subscriber: {:?}", e);
+                Err(Error::Message(e.to_string()))
+            }
+        }
+    }
+
+
+    async fn after_routes(&self, router: AxumRouter, _ctx: &AppContext) -> Result<AxumRouter> {
+        let router = router
+            .layer(OtelInResponseLayer::default())
+            .layer(OtelAxumLayer::default());
+        Ok(router)
+    }
+}

loco-extras/src/lib.rs

@@ -10,4 +10,5 @@
 //! * `initializer-extra-db` Adding extra DB connection
 //! * `initializer-multi-db` Adding extra DB's connection
 //! * `initializer-normalize-path` Normalize the request path
+//! * `initializer-opentelemetry` For adding opentelemetry tracing
 pub mod initializers;