✨ add ability to set route specific tags

Author: nicgirault

README.md

@@ -7,8 +7,19 @@ Datadog middleware for Connect JS / Express
 
 Add middleware immediately before your router.
 
-	app.use(require("connect-datadog")({}));
-	app.use(app.router);
+```javascript
+app.use(require("connect-datadog")({}));
+app.use(app.router);
+```
+
+You can add specific tags in other middlewares:
+
+```javascript
+const someMiddleware = (req, res, next) => {
+	req.ddTags = ['foo:bar']
+	next()
+}
+```
 
 ## Options
 
@@ -27,4 +38,3 @@ All options are optional.
 ## License
 
 View the [LICENSE](https://github.com/AppPress/node-connect-datadog/blob/master/LICENSE) file.
-

lib/index.js

@@ -41,10 +41,12 @@ module.exports = function (options) {
 		let end = res.end;
 		res.end = function (chunk, encoding) {
 			res.end = end;
-			res.end(chunk, encoding);
+      res.end(chunk, encoding);
+
+      const routeTags = req.ddTags || [];
+
+      let statTags = [...tags, ...routeTags];
 
-			let statTags = [...tags];
-			
 			const route = getRoute(req, base_url);
 			if (route.length > 0) {
 				statTags.push(`route:${route}`);

lib/index.test.js

@@ -38,9 +38,10 @@ describe('connectDatadog', () => {
     mockStatsDImplementation.increment.mockReset()
   })
 
-  const asyncConnectDatadogAndCallMiddleware = (options, timeoutInterval = 0) =>
+  const asyncConnectDatadogAndCallMiddleware = (options, timeoutInterval = 0, routeTags = undefined) =>
     new Promise(resolve => {
       const middleware = connectDatadog(options)
+      req.ddTags = routeTags
       middleware(req, res, next)
 
       timeoutInterval > 0
@@ -167,6 +168,20 @@ describe('connectDatadog', () => {
           expectConnectedToDatadog(stat, statTags)
         })
       })
+
+      describe('when a later middleware add a tag', () => {
+        it('appends the list of tags to the metric tag', async () => {
+          const stat = 'node.express.router'
+          const routeTags = ['foo:bar']
+          const statTags = [
+            `route:${req.route.path}`,
+            `response_code:${res.statusCode}`,
+          ]
+
+          await asyncConnectDatadogAndCallMiddleware({ response_code: true }, 0, routeTags)
+          expectConnectedToDatadog(stat, [...routeTags, ...statTags])
+        })
+      })
     })
 
     describe('path', () => {