add request tracing for cdn

Author: zhiyuanliang-ms

package-lock.json

@@ -59,6 +59,7 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
     #client: AppConfigurationClient;
     #clientEndpoint: string | undefined;
     #options: AzureAppConfigurationOptions | undefined;
+    #isCdnUsed: boolean;
     #isInitialLoadCompleted: boolean = false;
 
     // Refresh
@@ -80,11 +81,13 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
     constructor(
         client: AppConfigurationClient,
         clientEndpoint: string | undefined,
-        options: AzureAppConfigurationOptions | undefined
+        options: AzureAppConfigurationOptions | undefined,
+        isCdnUsed: boolean
     ) {
         this.#client = client;
         this.#clientEndpoint = clientEndpoint;
         this.#options = options;
+        this.#isCdnUsed = isCdnUsed;
 
         // Enable request tracing if not opt-out
         this.#requestTracingEnabled = requestTracingEnabled();
@@ -197,6 +200,7 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
         return {
             requestTracingEnabled: this.#requestTracingEnabled,
             initialLoadCompleted: this.#isInitialLoadCompleted,
+            isCdnUsed: this.#isCdnUsed,
             appConfigOptions: this.#options
         };
     }

src/AzureAppConfigurationImpl.ts

@@ -10,6 +10,11 @@ import * as RequestTracing from "./requestTracing/constants.js";
 
 const MIN_DELAY_FOR_UNHANDLED_ERROR: number = 5000; // 5 seconds
 
+// Empty token credential to be used when loading from CDN
+const emptyTokenCredential: TokenCredential = {
+    getToken: async () => ({ token: "", expiresOnTimestamp: 0 })
+};
+
 /**
  * Loads the data from Azure App Configuration service and returns an instance of AzureAppConfiguration.
  * @param connectionString  The connection string for the App Configuration store.
@@ -67,7 +72,7 @@ export async function load(
     }
 
     try {
-        const appConfiguration = new AzureAppConfigurationImpl(client, clientEndpoint, options);
+        const appConfiguration = new AzureAppConfigurationImpl(client, clientEndpoint, options, credentialOrOptions === emptyTokenCredential);
         await appConfiguration.load();
         return appConfiguration;
     } catch (error) {
@@ -93,10 +98,6 @@ export async function loadFromCdn(
     cdnEndpoint: string | URL,
     appConfigOptions?: AzureAppConfigurationOptions
 ): Promise<AzureAppConfiguration> {
-    const emptyTokenCredential: TokenCredential = {
-        getToken: async () => ({ token: "", expiresOnTimestamp: 0 })
-    };
-
     if (appConfigOptions === undefined) {
         appConfigOptions = { clientOptions: {}};
     }

src/load.ts

@@ -46,3 +46,4 @@ export enum RequestType {
 
 // Tag names
 export const KEY_VAULT_CONFIGURED_TAG = "UsesKeyVault";
+export const CDN_USED_TAG = "CDN";

src/requestTracing/constants.ts

@@ -13,6 +13,7 @@ import {
     HOST_TYPE_KEY,
     HostType,
     KEY_VAULT_CONFIGURED_TAG,
+    CDN_USED_TAG,
     KUBERNETES_ENV_VAR,
     NODEJS_DEV_ENV_VAL,
     NODEJS_ENV_VAR,
@@ -27,18 +28,19 @@ export function listConfigurationSettingsWithTrace(
     requestTracingOptions: {
         requestTracingEnabled: boolean;
         initialLoadCompleted: boolean;
+        isCdnUsed: boolean;
         appConfigOptions: AzureAppConfigurationOptions | undefined;
     },
     client: AppConfigurationClient,
     listOptions: ListConfigurationSettingsOptions
 ) {
-    const { requestTracingEnabled, initialLoadCompleted, appConfigOptions } = requestTracingOptions;
+    const { requestTracingEnabled, initialLoadCompleted, isCdnUsed, appConfigOptions } = requestTracingOptions;
 
     const actualListOptions = { ...listOptions };
     if (requestTracingEnabled) {
         actualListOptions.requestOptions = {
             customHeaders: {
-                [CORRELATION_CONTEXT_HEADER_NAME]: createCorrelationContextHeader(appConfigOptions, initialLoadCompleted)
+                [CORRELATION_CONTEXT_HEADER_NAME]: createCorrelationContextHeader(appConfigOptions, initialLoadCompleted, isCdnUsed)
             }
         };
     }
@@ -50,27 +52,28 @@ export function getConfigurationSettingWithTrace(
     requestTracingOptions: {
         requestTracingEnabled: boolean;
         initialLoadCompleted: boolean;
+        isCdnUsed: boolean;
         appConfigOptions: AzureAppConfigurationOptions | undefined;
     },
     client: AppConfigurationClient,
     configurationSettingId: ConfigurationSettingId,
     getOptions?: GetConfigurationSettingOptions,
 ) {
-    const { requestTracingEnabled, initialLoadCompleted, appConfigOptions } = requestTracingOptions;
+    const { requestTracingEnabled, initialLoadCompleted, isCdnUsed, appConfigOptions } = requestTracingOptions;
     const actualGetOptions = { ...getOptions };
 
     if (requestTracingEnabled) {
         actualGetOptions.requestOptions = {
             customHeaders: {
-                [CORRELATION_CONTEXT_HEADER_NAME]: createCorrelationContextHeader(appConfigOptions, initialLoadCompleted)
+                [CORRELATION_CONTEXT_HEADER_NAME]: createCorrelationContextHeader(appConfigOptions, initialLoadCompleted, isCdnUsed)
             }
         };
     }
 
     return client.getConfigurationSetting(configurationSettingId, actualGetOptions);
 }
 
-export function createCorrelationContextHeader(options: AzureAppConfigurationOptions | undefined, isInitialLoadCompleted: boolean): string {
+export function createCorrelationContextHeader(options: AzureAppConfigurationOptions | undefined, isInitialLoadCompleted: boolean, isCdnUsed: boolean): string {
     /*
     RequestType: 'Startup' during application starting up, 'Watch' after startup completed.
     Host: identify with defined envs
@@ -89,6 +92,9 @@ export function createCorrelationContextHeader(options: AzureAppConfigurationOpt
             tags.push(KEY_VAULT_CONFIGURED_TAG);
         }
     }
+    if (isCdnUsed) {
+        tags.push(CDN_USED_TAG);
+    }
 
     const contextParts: string[] = [];
     for (const [k, v] of keyValues) {

src/requestTracing/utils.ts

@@ -1,4 +1,4 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 
-export { load } from "../src";
+export { load, loadFromCdn } from "../src";

test/exportedApi.ts

@@ -6,7 +6,7 @@ import * as chaiAsPromised from "chai-as-promised";
 chai.use(chaiAsPromised);
 const expect = chai.expect;
 import { createMockedConnectionString, createMockedKeyValue, createMockedTokenCredential, mockAppConfigurationClientListConfigurationSettings, restoreMocks, sleepInMs } from "./utils/testHelper.js";
-import { load } from "./exportedApi.js";
+import { load, loadFromCdn } from "./exportedApi.js";
 
 class HttpRequestHeadersPolicy {
     headers: any;
@@ -77,6 +77,16 @@ describe("request tracing", function () {
         expect(correlationContext.includes("UsesKeyVault")).eq(true);
     });
 
+    it("should have cdn tag in correlation-context header", async () => {
+        try {
+            await loadFromCdn(fakeEndpoint);
+        } catch (e) { /* empty */ }
+        expect(headerPolicy.headers).not.undefined;
+        const correlationContext = headerPolicy.headers.get("Correlation-Context");
+        expect(correlationContext).not.undefined;
+        expect(correlationContext.includes("CDN")).eq(true);
+    });
+
     it("should detect env in correlation-context header", async () => {
         process.env.NODE_ENV = "development";
         try {