Simplified metrics middleware and backend

lib/api/api-router.js

@@ -187,7 +187,7 @@ module.exports = class ApiRouter {
         this.mapRouter = new MapRouter({ collaborators });
         this.templateRouter = new TemplateRouter({ collaborators });
         this.metadataBackend = metadataBackend;
-        this.pubSubMetricsBackend = PubSubMetricsBackend.build();
+        this.pubSubMetricsBackend = new PubSubMetricsBackend(this.serverOptions.pubSubMetrics);
     }
 
     route (app, routes) {
@@ -220,7 +220,10 @@ module.exports = class ApiRouter {
             apiRouter.use(sendResponse());
             apiRouter.use(syntaxError());
             apiRouter.use(errorMiddleware());
-            apiRouter.use(pubSubMetrics(this.pubSubMetricsBackend));
+            apiRouter.use(pubSubMetrics({
+                enabled: this.serverOptions.pubSubMetrics.enabled,
+                metricsBackend: this.pubSubMetricsBackend
+            }));
 
             paths.forEach(path => app.use(path, apiRouter));
         });

lib/api/middlewares/pubsub-metrics.js

@@ -3,8 +3,8 @@
 const EVENT_VERSION = '1';
 const MAX_LENGTH = 100;
 
-function pubSubMetrics (pubSubMetricsBackend) {
-    if (!pubSubMetricsBackend.isEnabled()) {
+function pubSubMetrics ({ enabled, metricsBackend }) {
+    if (!enabled) {
         return function pubSubMetricsDisabledMiddleware (req, res, next) {
             next();
         };
@@ -15,7 +15,7 @@ function pubSubMetrics (pubSubMetricsBackend) {
             const { event, attributes } = getEventData(req, res);
 
             if (event) {
-                pubSubMetricsBackend.sendEvent(event, attributes);
+                metricsBackend.send(event, attributes);
             }
         });