Middlewarify analysis-node-status endpoint

lib/cartodb/controllers/layergroup.js

@@ -163,31 +163,26 @@ LayergroupController.prototype.register = function(app) {
         cors(),
         userMiddleware,
         this.prepareContext,
-        this.analysisNodeStatus.bind(this)
+        this.analysisNodeStatus(this.analysisStatusBackend)
     );
 };
 
-LayergroupController.prototype.analysisNodeStatus = function(req, res, next) {
-    var self = this;
-
-    step(
-        function retrieveNodeStatus() {
-            self.analysisStatusBackend.getNodeStatus(res.locals, this);
-        },
-        function finish(err, nodeStatus, stats) {
+LayergroupController.prototype.analysisNodeStatus = function (analysisStatusBackend) {
+    return function analysisNodeStatusMiddleware(req, res, next) {
+        analysisStatusBackend.getNodeStatus(res.locals, (err, nodeStatus, stats) => {
             req.profiler.add(stats || {});
 
             if (err) {
                 err.label = 'GET NODE STATUS';
-                next(err);
-            } else {
-                self.sendResponse(req, res, nodeStatus, 200, {
-                    'Cache-Control': 'public,max-age=5',
-                    'Last-Modified': new Date().toUTCString()
-                });
+                return next(err);
             }
-        }
-    );
+
+            this.sendResponse(req, res, nodeStatus, 200, {
+                'Cache-Control': 'public,max-age=5',
+                'Last-Modified': new Date().toUTCString()
+            });
+        });
+    }.bind(this);
 };
 
 LayergroupController.prototype.getMapStoreMapConfigProvider = function (mapStore, userLimitsApi) {