add replica count tracing

Author: zhiyuanliang-ms

package-lock.json

@@ -33,7 +33,7 @@ import {
 } from "./featureManagement/constants.js";
 import { AzureKeyVaultKeyValueAdapter } from "./keyvault/AzureKeyVaultKeyValueAdapter.js";
 import { RefreshTimer } from "./refresh/RefreshTimer.js";
-import { getConfigurationSettingWithTrace, listConfigurationSettingsWithTrace, requestTracingEnabled } from "./requestTracing/utils.js";
+import { RequestTracingOptions, getConfigurationSettingWithTrace, listConfigurationSettingsWithTrace, requestTracingEnabled } from "./requestTracing/utils.js";
 import { KeyFilter, LabelFilter, SettingSelector } from "./types.js";
 import { ConfigurationClientManager } from "./ConfigurationClientManager.js";
 
@@ -197,11 +197,12 @@ export class AzureAppConfigurationImpl implements AzureAppConfiguration {
         return this.#featureFlagEnabled && !!this.#options?.featureFlagOptions?.refresh?.enabled;
     }
 
-    get #requestTraceOptions() {
+    get #requestTraceOptions(): RequestTracingOptions {
         return {
-            requestTracingEnabled: this.#requestTracingEnabled,
-            initialLoadCompleted: this.#isInitialLoadCompleted,
+            enabled: this.#requestTracingEnabled,
             appConfigOptions: this.#options,
+            initialLoadCompleted: this.#isInitialLoadCompleted,
+            replicaCount: this.#clientManager.getReplicaCount(),
             isFailoverRequest: this.#isFailoverRequest
         };
     }

src/AzureAppConfigurationImpl.ts

@@ -30,7 +30,7 @@ export class ConfigurationClientManager {
     #clientOptions: AppConfigurationClientOptions | undefined;
     #appConfigOptions: AzureAppConfigurationOptions | undefined;
     #validDomain: string;
-    #staticClients: ConfigurationClientWrapper[];
+    #staticClients: ConfigurationClientWrapper[]; // there should always be only one static client
     #dynamicClients: ConfigurationClientWrapper[];
     #lastFallbackClientRefreshTime: number = 0;
     #lastFallbackClientRefreshAttempt: number = 0;
@@ -96,7 +96,11 @@ export class ConfigurationClientManager {
         this.#isFailoverable = true;
     }
 
-    async getClients() : Promise<ConfigurationClientWrapper[]> {
+    getReplicaCount(): number {
+        return this.#dynamicClients.length;
+    }
+
+    async getClients(): Promise<ConfigurationClientWrapper[]> {
         if (!this.#isFailoverable) {
             return this.#staticClients;
         }

src/ConfigurationClientManager.ts

@@ -37,16 +37,20 @@ export const CONTAINER_APP_ENV_VAR = "CONTAINER_APP_NAME";
 export const KUBERNETES_ENV_VAR = "KUBERNETES_PORT";
 export const SERVICE_FABRIC_ENV_VAR = "Fabric_NodeName"; // See: https://docs.microsoft.com/en-us/azure/service-fabric/service-fabric-environment-variables-reference
 
-// Request Type
+// Request type
 export const REQUEST_TYPE_KEY = "RequestType";
 export enum RequestType {
     STARTUP = "Startup",
     WATCH = "Watch"
 }
 
-export const FEATURES_KEY = "Features";
+// Replica count
+export const REPLICA_COUNT_KEY = "ReplicaCount";
 
 // Tag names
-export const FAILOVER_REQUEST_TAG = "Failover";
 export const KEY_VAULT_CONFIGURED_TAG = "UsesKeyVault";
+export const FAILOVER_REQUEST_TAG = "Failover";
+
+// Compact feature tags
+export const FEATURES_KEY = "Features";
 export const LOAD_BALANCE_CONFIGURED_TAG = "LB";

src/requestTracing/constants.ts

@@ -20,29 +20,31 @@ import {
     RequestType,
     SERVICE_FABRIC_ENV_VAR,
     CORRELATION_CONTEXT_HEADER_NAME,
+    REPLICA_COUNT_KEY,
     FAILOVER_REQUEST_TAG,
     FEATURES_KEY,
     LOAD_BALANCE_CONFIGURED_TAG
 } from "./constants";
 
+export interface RequestTracingOptions {
+    enabled: boolean;
+    appConfigOptions: AzureAppConfigurationOptions | undefined;
+    initialLoadCompleted: boolean;
+    replicaCount: number;
+    isFailoverRequest: boolean;
+}
+
 // Utils
 export function listConfigurationSettingsWithTrace(
-    requestTracingOptions: {
-        requestTracingEnabled: boolean;
-        initialLoadCompleted: boolean;
-        appConfigOptions: AzureAppConfigurationOptions | undefined;
-        isFailoverRequest: boolean;
-    },
+    requestTracingOptions: RequestTracingOptions,
     client: AppConfigurationClient,
     listOptions: ListConfigurationSettingsOptions
 ) {
-    const { requestTracingEnabled, initialLoadCompleted, appConfigOptions, isFailoverRequest } = requestTracingOptions;
-
     const actualListOptions = { ...listOptions };
-    if (requestTracingEnabled) {
+    if (requestTracingOptions.enabled) {
         actualListOptions.requestOptions = {
             customHeaders: {
-                [CORRELATION_CONTEXT_HEADER_NAME]: createCorrelationContextHeader(appConfigOptions, initialLoadCompleted, isFailoverRequest)
+                [CORRELATION_CONTEXT_HEADER_NAME]: createCorrelationContextHeader(requestTracingOptions)
             }
         };
     }
@@ -51,53 +53,61 @@ export function listConfigurationSettingsWithTrace(
 }
 
 export function getConfigurationSettingWithTrace(
-    requestTracingOptions: {
-        requestTracingEnabled: boolean;
-        initialLoadCompleted: boolean;
-        appConfigOptions: AzureAppConfigurationOptions | undefined;
-        isFailoverRequest: boolean;
-    },
+    requestTracingOptions: RequestTracingOptions,
     client: AppConfigurationClient,
     configurationSettingId: ConfigurationSettingId,
     getOptions?: GetConfigurationSettingOptions,
 ) {
-    const { requestTracingEnabled, initialLoadCompleted, appConfigOptions, isFailoverRequest } = requestTracingOptions;
     const actualGetOptions = { ...getOptions };
 
-    if (requestTracingEnabled) {
+    if (requestTracingOptions.enabled) {
         actualGetOptions.requestOptions = {
             customHeaders: {
-                [CORRELATION_CONTEXT_HEADER_NAME]: createCorrelationContextHeader(appConfigOptions, initialLoadCompleted, isFailoverRequest)
+                [CORRELATION_CONTEXT_HEADER_NAME]: createCorrelationContextHeader(requestTracingOptions)
             }
         };
     }
 
     return client.getConfigurationSetting(configurationSettingId, actualGetOptions);
 }
 
-export function createCorrelationContextHeader(options: AzureAppConfigurationOptions | undefined, isInitialLoadCompleted: boolean, isFailoverRequest: boolean): string {
+export function createCorrelationContextHeader(requestTracingOptions: RequestTracingOptions): string {
     /*
     RequestType: 'Startup' during application starting up, 'Watch' after startup completed.
     Host: identify with defined envs
-    Env: identify by env `NODE_ENV` which is a popular but not standard.usually the value can be "development", "production".
+    Env: identify by env `NODE_ENV` which is a popular but not standard. Usually, the value can be "development", "production".
+    ReplicaCount: identify how many replicas are found
+    Features: LB
     UsersKeyVault
+    Failover
     */
     const keyValues = new Map<string, string | undefined>();
-    keyValues.set(REQUEST_TYPE_KEY, isInitialLoadCompleted ? RequestType.WATCH : RequestType.STARTUP);
+    const tags: string[] = [];
+
+    keyValues.set(REQUEST_TYPE_KEY, requestTracingOptions.initialLoadCompleted ? RequestType.WATCH : RequestType.STARTUP);
     keyValues.set(HOST_TYPE_KEY, getHostType());
     keyValues.set(ENV_KEY, isDevEnvironment() ? DEV_ENV_VAL : undefined);
-    if (options?.loadBalancingEnabled) {
-        keyValues.set(FEATURES_KEY, LOAD_BALANCE_CONFIGURED_TAG);
-    }
 
-    const tags: string[] = [];
-    if (options?.keyVaultOptions) {
-        const { credential, secretClients, secretResolver } = options.keyVaultOptions;
+    const appConfigOptions = requestTracingOptions.appConfigOptions;
+    if (appConfigOptions?.keyVaultOptions) {
+        const { credential, secretClients, secretResolver } = appConfigOptions.keyVaultOptions;
         if (credential !== undefined || secretClients?.length || secretResolver !== undefined) {
             tags.push(KEY_VAULT_CONFIGURED_TAG);
         }
     }
 
+    if (requestTracingOptions.isFailoverRequest) {
+        tags.push(FAILOVER_REQUEST_TAG);
+    }
+    if (requestTracingOptions.replicaCount > 0) {
+        keyValues.set(REPLICA_COUNT_KEY, requestTracingOptions.replicaCount.toString());
+    }
+
+    // Compact tags: Features=LB+...
+    if (appConfigOptions?.loadBalancingEnabled) {
+        keyValues.set(FEATURES_KEY, LOAD_BALANCE_CONFIGURED_TAG);
+    }
+
     const contextParts: string[] = [];
     for (const [k, v] of keyValues) {
         if (v !== undefined) {
@@ -108,10 +118,6 @@ export function createCorrelationContextHeader(options: AzureAppConfigurationOpt
         contextParts.push(tag);
     }
 
-    if (isFailoverRequest) {
-        contextParts.push(FAILOVER_REQUEST_TAG);
-    }
-
     return contextParts.join(",");
 }