add router subscription for code origin

Author: crysmags

packages/datadog-plugin-express/src/code_origin.js

@@ -22,6 +22,16 @@ class ExpressCodeOriginForSpansPlugin extends Plugin {
       if (layerTags.has(layer)) return
       layerTags.set(layer, entryTags(topOfStackFunc))
     })
+    this.addSub('apm:router:middleware:enter', ({ req, layer }) => {
+      const tags = layerTags.get(layer)
+      if (!tags) return
+      web.getContext(req).span?.addTags(tags)
+    })
+
+    this.addSub('apm:router:route:added', ({ topOfStackFunc, layer }) => {
+      if (layerTags.has(layer)) return
+      layerTags.set(layer, entryTags(topOfStackFunc))
+    })
   }
 }
 

packages/datadog-plugin-express/test/code_origin.spec.js

@@ -24,7 +24,7 @@ describe('Plugin', () => {
         const config = { codeOriginForSpans: { enabled: false } }
 
         describe(`with tracer config ${JSON.stringify(config)}`, () => {
-          before(() => agent.load(['express', 'http'], [{}, {}, { client: false }], config))
+          before(() => agent.load(['express', 'http', 'router'], [{}, { client: false }, {}], config))
 
           after(() => agent.close({ ritmReset: false, wipe: true }))
 
@@ -52,7 +52,7 @@ describe('Plugin', () => {
 
         for (const config of configs) {
           describe(`with tracer config ${JSON.stringify(config)}`, () => {
-            before(() => agent.load(['express', 'http'], [{}, {}, { client: false }], config))
+            before(() => agent.load(['express', 'http', 'router'], [{}, { client: false }, {}], config))
 
             after(() => agent.close({ ritmReset: false, wipe: true }))