Use targeting context accessor

src/client/src/pages/Home.jsx

@@ -39,7 +39,7 @@ function Home() {
           headers: {
             "Content-Type": "application/json",
           },
-          body: JSON.stringify({ UserId: currentUser ?? "" }),
+          body: JSON.stringify({ userId: currentUser ?? "" }),
         });
 
         if (response.ok) {

src/config.js

@@ -0,0 +1,8 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+module.exports = {
+    appConfigEndpoint: process.env.APPCONFIG_ENDPOINT,
+    appInsightsConnectionString: process.env.APPLICATIONINSIGHTS_CONNECTION_STRING,
+    port: process.env.PORT || "8080"
+};

src/featureManagement.js

@@ -0,0 +1,49 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+
+const { DefaultAzureCredential } = require("@azure/identity");
+const { load } = require("@azure/app-configuration-provider");
+const { FeatureManager, ConfigurationMapFeatureFlagProvider } = require("@microsoft/feature-management");
+const { createTelemetryPublisher } = require("@microsoft/feature-management-applicationinsights-node");
+const config = require("./config");
+
+// Variables to hold the App Configuration provider and feature manager instances
+let appConfig;
+let featureManager;
+
+// Initialize App Configuration provider and feature management
+async function initializeFeatureManagement(appInsightsClient, targetingContextAccessor) {
+    console.log("Loading feature flags from Azure App Configuration...");
+    appConfig = await load(config.appConfigEndpoint, new DefaultAzureCredential(), {
+        featureFlagOptions: {
+            enabled: true,
+            refresh: {
+                enabled: true
+            }
+        }
+    });
+    const featureFlagProvider = new ConfigurationMapFeatureFlagProvider(appConfig);
+
+    const publishTelemetry = createTelemetryPublisher(appInsightsClient);
+    featureManager = new FeatureManager(featureFlagProvider, {
+        onFeatureEvaluated: publishTelemetry,
+        targetingContextAccessor: targetingContextAccessor
+    });
+
+    return { featureManager, appConfig };
+}
+
+// Middleware to refresh configuration before each request
+const featureFlagRefreshMiddleware = (req, res, next) => {
+    // The configuration refresh happens asynchronously to the processing of your app's incoming requests.
+    // It will not block or slow down the incoming request that triggered the refresh. 
+    // The request that triggered the refresh may not get the updated configuration values, but later requests will get new configuration values.
+    appConfig?.refresh(); // intended to not await the refresh
+    next();
+};
+
+module.exports = {
+    initializeFeatureManagement,
+    featureFlagRefreshMiddleware
+};

src/package.json

@@ -7,8 +7,8 @@
   },
   "dependencies": {
     "@azure/app-configuration-provider": "latest",
-    "@microsoft/feature-management": "^2.0.0",
-    "@microsoft/feature-management-applicationinsights-node": "^2.0.0",
+    "@microsoft/feature-management": "2.1.0",
+    "@microsoft/feature-management-applicationinsights-node": "2.1.0",
     "applicationinsights": "^2.9.6",
     "express": "^4.19.2"
   }

src/routes.js

@@ -0,0 +1,30 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+const express = require("express");
+const router = express.Router();
+
+// Initialize routes with dependencies
+function initializeRoutes(featureManager, appInsightsClient) {
+    // API route to get greeting message with feature variants
+    router.get("/api/getGreetingMessage", async (req, res) => {
+        const variant = await featureManager.getVariant("Greeting");
+        res.status(200).send({
+            message: variant?.configuration
+        });
+    });
+
+    // API route to track like events
+    router.post("/api/like", (req, res) => {
+        const { userId } = req.body;
+        if (userId === undefined) {
+            return res.status(400).send({ error: "userId is required" });
+        }
+        appInsightsClient.trackEvent({ name: "Like" });
+        res.status(200).send({ message: "Like event logged successfully" });
+    });
+
+    return router;
+}
+
+module.exports = { initializeRoutes };

src/server.js

@@ -1,88 +1,53 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-const appConfigEndpoint = process.env.APPCONFIG_ENDPOINT;
-const appInsightsConnectionString = process.env.APPLICATIONINSIGHTS_CONNECTION_STRING;
-
-const applicationInsights = require("applicationinsights");
-applicationInsights.setup(appInsightsConnectionString).start();
+const config = require("./config");
 
 const express = require("express");
+const { targetingContextAccessor, requestStorageMiddleware } = require("./targetingContextAccessor");
+const { initializeAppInsights } = require("./telemetry");
+const { initializeFeatureManagement, featureFlagRefreshMiddleware } = require("./featureManagement");
+const { initializeRoutes } = require("./routes");
+
+// Initialize Express server
 const server = express();
 
-const { DefaultAzureCredential } = require("@azure/identity");
-const { load } = require("@azure/app-configuration-provider");
-const { FeatureManager, ConfigurationMapFeatureFlagProvider } = require("@microsoft/feature-management");
-const { createTelemetryPublisher, trackEvent } = require("@microsoft/feature-management-applicationinsights-node");
-let appConfig;
-let featureManager;
-async function initializeConfig() {
-    console.log("Loading configuration...");
-    appConfig = await load(appConfigEndpoint, new DefaultAzureCredential(), {
-        featureFlagOptions: {
-            enabled: true,
-            selectors: [
-                {
-                    keyFilter: "*"
-                }
-            ],
-            refresh: {
-                enabled: true,
-                refreshIntervalInMs: 10_000
-            }
-        }
-    });
+// Initialize Application Insights
+const appInsights = initializeAppInsights(targetingContextAccessor);
 
-    const featureFlagProvider = new ConfigurationMapFeatureFlagProvider(appConfig);
-    const publishTelemetry = createTelemetryPublisher(applicationInsights.defaultClient);
-    featureManager = new FeatureManager(featureFlagProvider, {
-        onFeatureEvaluated: publishTelemetry
-    });
-}
+// Global variables to store feature manager
+let featureManager;
 
 // Initialize the configuration and start the server
-initializeConfig()
-    .then(() => {
+async function startApp() {
+    try {
+        const result = await initializeFeatureManagement(
+            appInsights.defaultClient, 
+            targetingContextAccessor
+        );
+        featureManager = result.featureManager;
+
         console.log("Configuration loaded. Starting server...");
-        startServer();
-    })
-    .catch((error) => {
+
+        // Set up middleware
+        server.use(requestStorageMiddleware);
+        server.use(featureFlagRefreshMiddleware);
+        server.use(express.json());
+        server.use(express.static("public"));
+
+        // Set up routes
+        const routes = initializeRoutes(featureManager, appInsights.defaultClient);
+        server.use(routes);
+
+        // Start the server
+        server.listen(config.port, () => {
+            console.log(`Server is running at http://localhost:${config.port}`);
+        });
+    } catch (error) {
         console.error("Failed to load configuration:", error);
         process.exit(1);
-    });
-
-function startServer() {
-    // Use a middleware to refresh the configuration before each request
-    // The configuration refresh is triggered by the incoming requests to your web app. No refresh will occur if your app is idle.
-    server.use((req, res, next) => {
-        // The configuration refresh happens asynchronously to the processing of your app's incoming requests.
-        // It will not block or slow down the incoming request that triggered the refresh. 
-        // The request that triggered the refresh may not get the updated configuration values, but later requests will get new configuration values.
-        appConfig.refresh(); // intended to not await the refresh
-        next();
-    });
-    server.use(express.json());
-    server.use(express.static("public"));
-
-    server.get("/api/getGreetingMessage", async (req, res) => {
-        const { userId, groups } = req.query;
-        const variant = await featureManager.getVariant("Greeting", { userId: userId, groups: groups ? groups.split(",") : [] });
-        res.status(200).send({
-            message: variant?.configuration
-        });
-    });
-
-    server.post("/api/like", (req, res) => {
-        const { UserId } = req.body;
-        if (UserId === undefined) {
-            return res.status(400).send({ error: "UserId is required" });
-        }
-        trackEvent(applicationInsights.defaultClient, UserId, { name: "Like" });
-        res.status(200).send({ message: "Like event logged successfully" });
-    });
-
-    const port = process.env.PORT || "8080";
-    server.listen(port, () => {
-        console.log(`Server is running at http://localhost:${port}`);
-    });
+    }
 }
+
+// Start the application
+startApp();

src/targetingContextAccessor.js

@@ -0,0 +1,32 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+const { AsyncLocalStorage } = require("async_hooks");
+
+// Create AsyncLocalStorage for request access across async operations
+const requestAccessor = new AsyncLocalStorage();
+
+// Create targeting context accessor to get user information for feature targeting
+const targetingContextAccessor = {
+    getTargetingContext: () => {
+        const req = requestAccessor.getStore();
+        if (req === undefined) {
+            return undefined;
+        }
+        // read user and groups from request
+        const userId = req.query.userId ?? req.body.userId;
+        const groups = req.query.groups ?? req.body.groups;
+        // return an ITargetingContext with the appropriate user info
+        return { userId: userId, groups: groups ? groups.split(",") : [] };
+    }
+};
+
+// A middleware to store request in AsyncLocalStorage
+const requestStorageMiddleware = (req, res, next) => {
+    requestAccessor.run(req, next);
+};
+
+module.exports = {
+    targetingContextAccessor,
+    requestStorageMiddleware
+};

src/telemetry.js

@@ -0,0 +1,22 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+
+const config = require('./config');
+const applicationInsights = require("applicationinsights");
+const { createTargetingTelemetryProcessor } = require("@microsoft/feature-management-applicationinsights-node");
+
+// Initialize Application Insights
+const initializeAppInsights = (targetingContextAccessor) => {
+    applicationInsights.setup(config.appInsightsConnectionString).start();
+
+    // Use the targeting telemetry processor to attach targeting id to the telemetry data sent to Application Insights.
+    applicationInsights.defaultClient.addTelemetryProcessor(
+        createTargetingTelemetryProcessor(targetingContextAccessor)
+    );
+
+    return applicationInsights;
+};
+
+module.exports = {
+    initializeAppInsights
+};