feat(signer): add metrics (Commit-Boost#197)

* Add endpoints metrics

* Add grafana dashboard

* Add more stats to dashboard

* Fix clippy

* Fix doc comments

* Make signer metrics function private

* Export signer dashboard for public use

crates/signer/Cargo.toml

@@ -7,6 +7,7 @@ publish = false
 
 [dependencies]
 cb-common.workspace = true
+cb-metrics.workspace = true
 
 # ethereum
 alloy.workspace = true
@@ -21,6 +22,7 @@ tokio.workspace = true
 
 # telemetry
 tracing.workspace = true
+prometheus.workspace = true
 
 # crypto
 blst.workspace = true

crates/signer/src/constants.rs

@@ -0,0 +1,3 @@
+pub const GET_PUBKEYS_ENDPOINT_TAG: &str = "get_pubkeys";
+pub const GENERATE_PROXY_KEY_ENDPOINT_TAG: &str = "generate_proxy_key";
+pub const REQUEST_SIGNATURE_ENDPOINT_TAG: &str = "request_signature";

crates/signer/src/lib.rs

@@ -1,3 +1,5 @@
+mod constants;
 pub mod error;
 pub mod manager;
+mod metrics;
 pub mod service;

crates/signer/src/metrics.rs

@@ -0,0 +1,34 @@
+//! Metrics for Signer module
+
+use axum::http::Uri;
+use cb_common::commit::constants::{
+    GENERATE_PROXY_KEY_PATH, GET_PUBKEYS_PATH, REQUEST_SIGNATURE_PATH,
+};
+use lazy_static::lazy_static;
+use prometheus::{register_int_counter_vec_with_registry, IntCounterVec, Registry};
+
+use crate::constants::{
+    GENERATE_PROXY_KEY_ENDPOINT_TAG, GET_PUBKEYS_ENDPOINT_TAG, REQUEST_SIGNATURE_ENDPOINT_TAG,
+};
+
+lazy_static! {
+    pub static ref SIGNER_METRICS_REGISTRY: Registry =
+        Registry::new_custom(Some("cb_signer".to_string()), None).unwrap();
+
+    /// Status code returned by endpoint
+    pub static ref SIGNER_STATUS: IntCounterVec = register_int_counter_vec_with_registry!(
+        "signer_status_code_total",
+        "HTTP status code returned by signer",
+        &["http_status_code", "endpoint"],
+        SIGNER_METRICS_REGISTRY
+    ).unwrap();
+}
+
+pub fn uri_to_tag(uri: &Uri) -> &str {
+    match uri.path() {
+        GET_PUBKEYS_PATH => GET_PUBKEYS_ENDPOINT_TAG,
+        GENERATE_PROXY_KEY_PATH => GENERATE_PROXY_KEY_ENDPOINT_TAG,
+        REQUEST_SIGNATURE_PATH => REQUEST_SIGNATURE_ENDPOINT_TAG,
+        _ => "unknown endpoint",
+    }
+}

crates/signer/src/service.rs

@@ -24,13 +24,18 @@ use cb_common::{
     constants::COMMIT_BOOST_VERSION,
     types::{Jwt, ModuleId},
 };
+use cb_metrics::provider::MetricsProvider;
 use eyre::{Context, Result};
 use headers::{authorization::Bearer, Authorization};
 use tokio::{net::TcpListener, sync::RwLock};
 use tracing::{debug, error, info, warn};
 use uuid::Uuid;
 
-use crate::{error::SignerModuleError, manager::SigningManager};
+use crate::{
+    error::SignerModuleError,
+    manager::SigningManager,
+    metrics::{uri_to_tag, SIGNER_METRICS_REGISTRY, SIGNER_STATUS},
+};
 
 /// Implements the Signer API and provides a service for signing requests
 pub struct SigningService;
@@ -72,13 +77,15 @@ impl SigningService {
         info!(version = COMMIT_BOOST_VERSION, modules =? module_ids, port =? config.server_port, loaded_consensus, loaded_proxies, "Starting signing service");
 
         let state = SigningState { manager: RwLock::new(manager).into(), jwts: config.jwts.into() };
+        SigningService::init_metrics()?;
 
         let app = axum::Router::new()
             .route(REQUEST_SIGNATURE_PATH, post(handle_request_signature))
             .route(GET_PUBKEYS_PATH, get(handle_get_pubkeys))
             .route(GENERATE_PROXY_KEY_PATH, post(handle_generate_proxy))
             .with_state(state.clone())
-            .route_layer(middleware::from_fn_with_state(state.clone(), jwt_auth));
+            .route_layer(middleware::from_fn_with_state(state.clone(), jwt_auth))
+            .route_layer(middleware::from_fn(log_request));
         let status_router = axum::Router::new().route(STATUS_PATH, get(handle_status));
 
         let address = SocketAddr::from(([0, 0, 0, 0], config.server_port));
@@ -88,6 +95,10 @@ impl SigningService {
             .await
             .wrap_err("signer server exited")
     }
+
+    fn init_metrics() -> Result<()> {
+        MetricsProvider::load_and_run(SIGNER_METRICS_REGISTRY.clone())
+    }
 }
 
 /// Authentication middleware layer
@@ -109,6 +120,14 @@ async fn jwt_auth(
     Ok(next.run(req).await)
 }
 
+/// Requests logging middleware layer
+async fn log_request(req: Request, next: Next) -> Result<Response, SignerModuleError> {
+    let url = &req.uri().clone();
+    let response = next.run(req).await;
+    SIGNER_STATUS.with_label_values(&[response.status().as_str(), uri_to_tag(url)]).inc();
+    Ok(response)
+}
+
 /// Status endpoint for the Signer API
 async fn handle_status() -> Result<impl IntoResponse, SignerModuleError> {
     Ok((StatusCode::OK, "OK"))