4 files changed, 95 insertions, 0 deletions
diff --git a/lib/warden-middleware/Cargo.toml b/lib/warden-middleware/Cargo.toml
new file mode 100644
index 0000000..b23e61e
--- /dev/null
+++ b/lib/warden-middleware/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "warden-middleware"
+version = "0.1.0"
+edition = "2024"
+license.workspace = true
+homepage.workspace = true
+documentation.workspace = true
+description.workspace = true
+publish = false
+
+[dependencies]
+axum.workspace = true
+metrics.workspace = true
+metrics-exporter-prometheus.workspace = true
+tower-http = { workspace = true, features = [
+    "request-id",
+] }
+tracing.workspace = true
diff --git a/lib/warden-middleware/src/lib.rs b/lib/warden-middleware/src/lib.rs
new file mode 100644
index 0000000..6e3a0f4
--- /dev/null
+++ b/lib/warden-middleware/src/lib.rs
@@ -0,0 +1,20 @@
+mod metrics;
+mod trace_layer;
+
+use metrics::*;
+use trace_layer::*;
+
+use axum::{Router, http::HeaderName, middleware};
+use tower_http::request_id::{MakeRequestUuid, PropagateRequestIdLayer, SetRequestIdLayer};
+
+const REQUEST_ID_HEADER: &str = "x-request-id";
+
+pub fn apply<T: Clone + Send + Sync + 'static>(router: Router<T>) -> Router<T> {
+    let x_request_id = HeaderName::from_static(REQUEST_ID_HEADER);
+
+    let router = router.layer(PropagateRequestIdLayer::new(x_request_id.clone()));
+
+    apply_trace_context_middleware(router)
+        .layer(SetRequestIdLayer::new(x_request_id, MakeRequestUuid))
+        .route_layer(middleware::from_fn(apply_metrics_middleware))
+}
diff --git a/lib/warden-middleware/src/metrics.rs b/lib/warden-middleware/src/metrics.rs
new file mode 100644
index 0000000..8644160
--- /dev/null
+++ b/lib/warden-middleware/src/metrics.rs
@@ -0,0 +1,33 @@
+use std::time::Instant;
+
+use axum::{
+    extract::{MatchedPath, Request},
+    middleware::Next,
+    response::IntoResponse,
+};
+
+pub async fn apply_metrics_middleware(req: Request, next: Next) -> impl IntoResponse {
+    let start = Instant::now();
+    let path = if let Some(matched_path) = req.extensions().get::<MatchedPath>() {
+        matched_path.as_str().to_owned()
+    } else {
+        req.uri().path().to_owned()
+    };
+    let method = req.method().clone();
+
+    let response = next.run(req).await;
+
+    let latency = start.elapsed().as_secs_f64();
+    let status = response.status().as_u16().to_string();
+
+    let labels = [
+        ("method", method.to_string()),
+        ("path", path),
+        ("status", status),
+    ];
+
+    metrics::counter!("http_requests_total", &labels).increment(1);
+    metrics::histogram!("http_requests_duration_seconds", &labels).record(latency);
+
+    response
+}
diff --git a/lib/warden-middleware/src/trace_layer.rs b/lib/warden-middleware/src/trace_layer.rs
new file mode 100644
index 0000000..5173e8d
--- /dev/null
+++ b/lib/warden-middleware/src/trace_layer.rs
@@ -0,0 +1,24 @@
+use axum::{Router, http::Request};
+use tower_http::trace::TraceLayer;
+use tracing::info_span;
+
+use super::REQUEST_ID_HEADER;
+
+pub fn apply_trace_context_middleware<T: Clone + Send + Sync + 'static>(
+    router: Router<T>,
+) -> Router<T> {
+    router.layer(
+        TraceLayer::new_for_http().make_span_with(|request: &Request<_>| {
+            let request_id = request
+                .headers()
+                .get(REQUEST_ID_HEADER)
+                .expect("should have been applied already");
+
+            info_span!(
+                "http_request",
+                request_id = ?request_id,
+                headers = ?request.headers()
+            )
+        }),
+    )
+}