[SVLS-5649] Add HTTP Context Propagation to Azure Functions (#5839)

As drive-by improve readability

Author: jcstorms1

packages/datadog-plugin-azure-functions/src/index.js

@@ -19,14 +19,15 @@ class AzureFunctionsPlugin extends TracingPlugin {
   static get operation () { return 'invoke' }
   static get kind () { return 'server' }
   static get type () { return 'serverless' }
-
   static get prefix () { return 'tracing:datadog:azure:functions:invoke' }
 
   bindStart (ctx) {
-    const { functionName, methodName } = ctx
+    const { functionName, methodName, httpRequest } = ctx
     const store = storage('legacy').getStore()
-
+    // httpRequest.headers is a map
+    const childOf = this._tracer.extract('http_headers', Object.fromEntries(httpRequest.headers))
     const span = this.startSpan(this.operationName(), {
+      childOf,
       service: this.serviceName(),
       type: 'serverless',
       meta: {
@@ -52,7 +53,7 @@ class AzureFunctionsPlugin extends TracingPlugin {
     const path = (new URL(httpRequest.url)).pathname
     const req = {
       method: httpRequest.method,
-      headers: Object.fromEntries(httpRequest.headers.entries()),
+      headers: Object.fromEntries(httpRequest.headers),
       url: path
     }
 

packages/datadog-plugin-azure-functions/test/integration-test/client.spec.js

@@ -50,6 +50,18 @@ describe('esm', () => {
         assert.propertyVal(payload[0][0], 'name', 'azure.functions.invoke')
       })
     }).timeout(50000)
+
+    it('propagates context to child requests', async () => {
+      const envArgs = {
+        PATH: `${sandbox.folder}/node_modules/azure-functions-core-tools/bin:${process.env.PATH}`
+      }
+      proc = await spawnPluginIntegrationTestProc(sandbox.folder, 'func', ['start'], agent.port, undefined, envArgs)
+
+      return curlAndAssertMessage(agent, 'http://127.0.0.1:7071/api/httptest2', ({ headers, payload }) => {
+        assert.strictEqual(payload.length, 2)
+        assert.strictEqual(payload[0][0].parent_id, payload[1][1].span_id)
+      })
+    }).timeout(50000)
   })
 })
 

packages/datadog-plugin-azure-functions/test/integration-test/fixtures/src/functions/server.mjs

@@ -13,3 +13,15 @@ app.http('httptest', {
   authLevel: 'anonymous',
   handler: handlerFunction
 })
+
+app.http('httptest2', {
+  methods: ['GET'],
+  authLevel: 'anonymous',
+  handler: async (request, context) => {
+    await fetch('http://127.0.0.1:7071/api/httptest')
+    return {
+      status: 200,
+      body: 'Hello Datadog 2!'
+    }
+  }
+})