CLDSRV-717: Prometheus use aggregate registry

for cluster mode

Author: BourgoisMickael

lib/utilities/monitoringHandler.js

@@ -215,16 +215,29 @@ function writeResponse(res, error, results, cb) {
     });
 }
 
+const workers = process.env.S3BACKEND === 'mem' ? 1 : config.clusters || 1;
+const isCluster = workers > 1;
+const registry = isCluster ? new client.AggregatorRegistry() : client.register;
+const getMetrics = isCluster ?
+    registry.clusterMetrics.bind(registry) : registry.metrics.bind(registry);
 
 async function routeHandler(req, res, cb) {
     if (req.method !== 'GET') {
         return cb(errors.BadRequest, []);
     }
-    const promMetrics = await client.register.metrics();
+    let promMetrics;
+    try {
+        // Catch timeout on IPC between worker and primary
+        // prom-client has a 5s hardcoded timeout
+        promMetrics = await getMetrics();
+    } catch (err) {
+        return cb(err, { message: err.toString() });
+    }
+
     const contentLen = Buffer.byteLength(promMetrics, 'utf8');
     res.writeHead(200, {
         'Content-Length': contentLen,
-        'Content-Type': client.register.contentType,
+        'Content-Type': registry.contentType,
     });
     res.end(promMetrics);
     return undefined;