[MAINT] retry mechanism using axios-retry

example/index.js

@@ -3,10 +3,14 @@ const { Client } = pkg;
 
 const client = new Client('1c100d25-4c3f-487b-b198-3b3d01df5794');
 
+console.log('Starting application');
+
 setInterval(() => {
   const target = {
     identifier: 'harness',
   };
   const value = client.boolVariation('test', target, false);
   console.log('Evaluation for flag test and target: ', value, target);
 }, 10000);
+
+console.log('Application started');

package.json

@@ -57,6 +57,7 @@
   },
   "dependencies": {
     "axios": "^0.21.1",
+    "axios-retry": "^3.2.0",
     "eventsource": "^1.1.0",
     "jwt-decode": "^3.1.2",
     "keyv": "^4.0.3",

src/client.ts

@@ -1,5 +1,7 @@
 import * as events from 'events';
 import jwt_decode from 'jwt-decode';
+import axios from 'axios';
+import axiosRetry from 'axios-retry';
 import { Claims, Options, Target } from './types';
 import { Configuration, ClientApi, FeatureConfig, Variation } from './openapi';
 import { VERSION } from './version';
@@ -10,6 +12,8 @@ import { defaultOptions } from './constants';
 import { Repository, StorageRepository } from './repository';
 import { MetricsProcessor, MetricsProcessorInterface } from './metrics';
 
+axios.defaults.timeout = 30000;
+axiosRetry(axios, { retries: 3, retryDelay: axiosRetry.exponentialDelay });
 const log = defaultOptions.logger;
 
 export default class Client {
@@ -29,6 +33,10 @@ export default class Client {
 
   constructor(sdkKey: string, options: Options = {}) {
     this.sdkKey = sdkKey;
+    if (options.pollInterval < 1000) {
+      options.pollInterval = defaultOptions.pollInterval;
+      log.warn('Polling interval cannot be lower than 1000 ms');
+    }
     this.options = { ...defaultOptions, ...options };
 
     this.configuration = new Configuration({
@@ -45,27 +53,30 @@ export default class Client {
       this.options.store,
     );
     this.evaluator = new Evaluator(this.repository);
-
     this.api = new ClientApi(this.configuration);
     this.run();
   }
 
-  private async authenticate(): Promise<string> {
-    const response = await this.api.authenticate({
-      apiKey: this.sdkKey,
-    });
-    this.authToken = response.data.authToken;
-    this.configuration.accessToken = this.authToken;
+  private async authenticate(): Promise<void> {
+    try {
+      const response = await this.api.authenticate({
+        apiKey: this.sdkKey,
+      });
+      this.authToken = response.data.authToken;
+      this.configuration.accessToken = this.authToken;
 
-    const decoded: Claims = jwt_decode(this.authToken);
+      const decoded: Claims = jwt_decode(this.authToken);
 
-    this.environment = decoded.environment;
-    this.cluster = decoded.clusterIdentifier || '1';
-    return this.authToken;
+      this.environment = decoded.environment;
+      this.cluster = decoded.clusterIdentifier || '1';
+    } catch (error) {
+      console.error('Error while authenticating, err: ', error);
+    }
   }
 
   private async run(): Promise<void> {
     await this.authenticate();
+
     this.pollProcessor = new PollingProcessor(
       this.environment,
       this.cluster,
@@ -114,7 +125,9 @@ export default class Client {
       target,
       defaultValue,
       (fc: FeatureConfig, target: Target, variation: Variation) => {
-        this.metricsProcessor.enqueue(target, fc, variation);
+        if (this.metricsProcessor) {
+          this.metricsProcessor.enqueue(target, fc, variation);
+        }
       },
     );
   }
@@ -129,7 +142,9 @@ export default class Client {
       target,
       defaultValue,
       (fc: FeatureConfig, target: Target, variation: Variation) => {
-        this.metricsProcessor.enqueue(target, fc, variation);
+        if (this.metricsProcessor) {
+          this.metricsProcessor.enqueue(target, fc, variation);
+        }
       },
     );
   }
@@ -144,7 +159,9 @@ export default class Client {
       target,
       defaultValue,
       (fc: FeatureConfig, target: Target, variation: Variation) => {
-        this.metricsProcessor.enqueue(target, fc, variation);
+        if (this.metricsProcessor) {
+          this.metricsProcessor.enqueue(target, fc, variation);
+        }
       },
     );
   }
@@ -159,18 +176,20 @@ export default class Client {
       target,
       defaultValue,
       (fc: FeatureConfig, target: Target, variation: Variation) => {
-        this.metricsProcessor.enqueue(target, fc, variation);
+        if (this.metricsProcessor) {
+          this.metricsProcessor.enqueue(target, fc, variation);
+        }
       },
     );
   }
 
   close(): void {
     this.pollProcessor.close();
-    if (this.options.enableStream) {
+    if (this.streamProcessor) {
       this.streamProcessor.close();
     }
-    if (this.options.enableAnalytics) {
+    if (this.metricsProcessor) {
       this.metricsProcessor.close();
     }
   }
-}
+}

src/constants.ts

@@ -31,14 +31,12 @@ export const BASE_URL = 'https://config.ff.harness.io/api/1.0',
   SECOND = 1000,
   MINUTE = 60 * SECOND,
   PULL_INTERVAL = 1 * MINUTE,
-  PERSIST_INTERVAL = 1 * MINUTE,
   EVENTS_SYNC_INTERVAL = 1 * MINUTE;
 
 export const defaultOptions: Options = {
   baseUrl: BASE_URL,
   eventsUrl: EVENTS_URL,
   pollInterval: PULL_INTERVAL,
-  persistInterval: PERSIST_INTERVAL,
   eventsSyncInterval: EVENTS_SYNC_INTERVAL,
   enableStream: true,
   enableAnalytics: true,

src/polling.ts

@@ -11,7 +11,7 @@ export class PollingProcessor {
   private environment: string;
   private cluster: string;
   private api: ClientApi;
-  private stopped = false;
+  private stopped = true;
   private options: Options;
   private repository: Repository
 
@@ -35,7 +35,7 @@ export class PollingProcessor {
     });
 
     eventBus.on(Event.DISCONNECTED, () => {
-      this.resume();
+      this.start();
     });
   }
 
@@ -99,23 +99,23 @@ export class PollingProcessor {
   }
 
   start(): void {
+    if (!this.stopped) {
+      log.info('PollingProcessor already started');
+      return;
+    }
     log.info(
       'Starting PollingProcessor with request interval: ',
       this.options.pollInterval,
     );
+    this.stopped = false;
     this.poll();
   }
 
   private stop(): void {
-    log.info('Pausing PollingProcessor');
+    log.info('Stopping PollingProcessor');
     this.stopped = true;
   }
 
-  resume(): void {
-    log.info('Resuming PollingProcessor');
-    this.stopped = false;
-  }
-
   close(): void {
     log.info('Closing PollingProcessor');
     this.stop();

src/streaming.ts

@@ -124,7 +124,7 @@ export class StreamProcessor {
     return this.eventSource.readyState == StreamProcessor.CONNECTED;
   }
 
-  private stop(): void {
+  stop(): void {
     log.info('Stopping StreamProcessor');
     this.eventSource.close();
     this.eventBus.emit(Event.DISCONNECTED);