Publish EL Info in Metrics (#7052)

Since we now know the EL version, we should publish this to our metrics periodically.

beacon_node/execution_layer/src/engine_api/http.rs

@@ -1242,6 +1242,10 @@ impl HttpJsonRpc {
         } else {
             let engine_version = self.get_client_version_v1().await?;
             *lock = Some(CachedResponse::new(engine_version.clone()));
+            if !engine_version.is_empty() {
+                // reset metric gauge when there's a fresh fetch
+                crate::metrics::reset_execution_layer_info_gauge();
+            }
             Ok(engine_version)
         }
     }

beacon_node/execution_layer/src/lib.rs

@@ -1554,10 +1554,14 @@ impl<E: EthSpec> ExecutionLayer<E> {
         &self,
         age_limit: Option<Duration>,
     ) -> Result<Vec<ClientVersionV1>, Error> {
-        self.engine()
+        let versions = self
+            .engine()
             .request(|engine| engine.get_engine_version(age_limit))
             .await
-            .map_err(Into::into)
+            .map_err(Into::<Error>::into)?;
+        metrics::expose_execution_layer_info(&versions);
+
+        Ok(versions)
     }
 
     /// Used during block production to determine if the merge has been triggered.

beacon_node/execution_layer/src/metrics.rs

@@ -116,3 +116,29 @@ pub static EXECUTION_LAYER_PAYLOAD_BIDS: LazyLock<Result<IntGaugeVec>> = LazyLoc
         &["source"]
     )
 });
+pub static EXECUTION_LAYER_INFO: LazyLock<Result<IntGaugeVec>> = LazyLock::new(|| {
+    try_create_int_gauge_vec(
+        "execution_layer_info",
+        "The build of the execution layer connected to lighthouse",
+        &["code", "name", "version", "commit"],
+    )
+});
+
+pub fn reset_execution_layer_info_gauge() {
+    let _ = EXECUTION_LAYER_INFO.as_ref().map(|gauge| gauge.reset());
+}
+
+pub fn expose_execution_layer_info(els: &Vec<crate::ClientVersionV1>) {
+    for el in els {
+        set_gauge_vec(
+            &EXECUTION_LAYER_INFO,
+            &[
+                &el.code.to_string(),
+                &el.name,
+                &el.version,
+                &el.commit.to_string(),
+            ],
+            1,
+        );
+    }
+}