Centralize common headers, this will help up to move biz metrics out of the process

lib/api/map/preview-template-controller.js

@@ -346,11 +346,9 @@ function incrementMapViews ({ metadataBackend }) {
                 return next();
             }
 
-            const statTag = mapConfig.obj().stat_tag;
+            res.locals.mapConfig = mapConfig;
 
-            if (statTag) {
-                res.set('Carto-Stat-Tag', `${statTag}`);
-            }
+            const statTag = mapConfig.obj().stat_tag;
 
             metadataBackend.incMapviewCount(user, statTag, (err) => {
                 if (err) {

lib/api/middlewares/error-middleware.js

@@ -1,5 +1,7 @@
 'use strict';
 
+const setCommonHeaders = require('../../utils/common-headers');
+
 module.exports = function errorMiddleware (/* options */) {
     return function error (err, req, res, next) {
         const { logger } = res.locals;
@@ -7,21 +9,23 @@ module.exports = function errorMiddleware (/* options */) {
 
         logger.error({ error: errors });
 
-        const errorResponseBody = {
-            errors: errors.map(errorMessage),
-            errors_with_context: errors.map(errorMessageWithContext)
-        };
+        setCommonHeaders(req, res, () => {
+            const errorResponseBody = {
+                errors: errors.map(errorMessage),
+                errors_with_context: errors.map(errorMessageWithContext)
+            };
 
-        // If a callback was requested, force status to 200
-        res.status(req.query.callback ? 200 : findStatusCode(errors[0]));
+            // If a callback was requested, force status to 200
+            res.status(req.query.callback ? 200 : findStatusCode(errors[0]));
 
-        if (req.query && req.query.callback) {
-            res.jsonp(errorResponseBody);
-        } else {
-            res.json(errorResponseBody);
-        }
+            if (req.query && req.query.callback) {
+                res.jsonp(errorResponseBody);
+            } else {
+                res.json(errorResponseBody);
+            }
 
-        return next();
+            return next();
+        });
     };
 };
 

lib/api/middlewares/increment-map-view-count.js

@@ -5,11 +5,6 @@ module.exports = function incrementMapViewCount (metadataBackend) {
         const { mapConfig, user, logger } = res.locals;
         const statTag = mapConfig.obj().stat_tag;
 
-        if (statTag) {
-            res.set('Carto-Stat-Tag', `${statTag}`);
-        }
-
-        // Error won't blow up, just be logged.
         metadataBackend.incMapviewCount(user, statTag, (err) => {
             if (err) {
                 err.message = `Failed to increment mapview count for user '${user}'. ${err.message}`;

lib/api/middlewares/send-response.js

@@ -1,20 +1,24 @@
 'use strict';
 
+const setCommonHeaders = require('../../utils/common-headers');
+
 module.exports = function sendResponse () {
     return function sendResponseMiddleware (req, res, next) {
-        res.status(res.statusCode);
+        setCommonHeaders(req, res, () => {
+            res.status(res.statusCode);
 
-        if (Buffer.isBuffer(res.body)) {
-            res.send(res.body);
+            if (Buffer.isBuffer(res.body)) {
+                res.send(res.body);
+                return next();
+            }
+
+            if (req.query.callback) {
+                res.jsonp(res.body);
+                return next();
+            }
+
+            res.json(res.body);
             return next();
-        }
-
-        if (req.query.callback) {
-            res.jsonp(res.body);
-            return next();
-        }
-
-        res.json(res.body);
-        return next();
+        });
     };
 };

lib/api/middlewares/user.js

@@ -18,7 +18,7 @@ module.exports = function user (metadataBackend) {
             }
 
             res.locals.userId = userId;
-            res.set('Carto-User-Id', `${userId}`);
+
             return next();
         });
     };