FFM-12374 Retry enhancements (#123)

Author: erdirowlands

Diff for: package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@harnessio/ff-nodejs-server-sdk",
-  "version": "1.8.4",
+  "version": "1.8.5",
   "description": "Feature flags SDK for NodeJS environments",
   "main": "dist/cjs/index.js",
   "module": "dist/esm/index.mjs",
@@ -23,7 +23,7 @@
     "@types/node": "^14.17.11",
     "@typescript-eslint/eslint-plugin": "~5.62.0",
     "@typescript-eslint/parser": "~5.62.0",
-    "esbuild": "^0.19.11",
+    "esbuild": "^0.25.2",
     "eslint": "~7.30.0",
     "eslint-config-prettier": "~8.3.0",
     "eslint-plugin-jest": "~24.3.6",
@@ -61,7 +61,7 @@
   },
   "dependencies": {
     "axios": "^1.7.3",
-    "axios-retry": "^3.9.1",
+    "axios-retry": "4.5.0",
     "jwt-decode": "^3.1.2",
     "keyv": "^4.5.4",
     "keyv-file": "^0.3.0",

Diff for: package.json

@@ -130,9 +130,14 @@ export default class Client {
       this.initialize(Processor.POLL);
     });
 
-    this.eventBus.on(PollerEvent.ERROR, () => {
+    this.eventBus.on(PollerEvent.ERROR, (error) => {
       this.failure = true;
-      this.eventBus.emit(Event.FAILED);
+      this.eventBus.emit(
+        Event.FAILED,
+        new Error(
+          `Failed to load flags or groups: ${error?.message ?? 'unknown'}`,
+        ),
+      );
     });
 
     this.eventBus.on(StreamEvent.READY, () => {
@@ -290,7 +295,6 @@ export default class Client {
     if (!this.waitForInitializePromise) {
       if (this.initialized) {
         this.waitForInitializePromise = Promise.resolve(this);
-        infoSDKInitOK(this.log);
       } else if (!this.initialized && this.failure) {
         // We unblock the call even if initialization has failed. We've
         // already warned the user that initialization has failed with the reason and that
@@ -305,10 +309,35 @@ export default class Client {
         });
       }
     }
-
     return this.waitForInitializePromise;
   }
 
+  private axiosRetryCondition(error) {
+    if (axiosRetry.isNetworkOrIdempotentRequestError(error)) {
+      return true;
+    }
+
+    // retry if connection is aborted
+    if (error.code === 'ECONNABORTED') {
+      return true;
+    }
+
+    // Auth is a POST request so not covered by isNetworkOrIdempotentRequestError and it's not an aborted connection
+    const status = error?.response?.status;
+    const url = error?.config?.url ?? '';
+
+    if (
+      url.includes('client/auth') &&
+      status >= 500 &&
+      status <= 599
+    ) {
+      return true;
+    }
+
+    // Otherwise do not retry
+    return false;
+  }
+
   private createAxiosInstanceWithRetries(options: Options): AxiosInstance {
     let axiosConfig: AxiosRequestConfig = {
       timeout: options.axiosTimeout,
@@ -327,8 +356,40 @@ export default class Client {
 
     const instance: AxiosInstance = axios.create(axiosConfig);
     axiosRetry(instance, {
-      retries: 3,
+      retries: options.axiosRetries,
       retryDelay: axiosRetry.exponentialDelay,
+      retryCondition: this.axiosRetryCondition,
+      shouldResetTimeout: true,
+      onRetry: (retryCount, error, requestConfig) => {
+        // Get the URL without query parameters for cleaner logs
+        const url = requestConfig.url?.split('?')[0] || 'unknown URL';
+        const method = requestConfig.method?.toUpperCase() || 'unknown method';
+
+        const retryMessage =
+          `Retrying request (${retryCount}/${options.axiosRetries}) to ${method} ${url} - ` +
+          `Error: ${error.code || 'unknown'} - ${error.message}`;
+
+        // Log first retry as warn and subsequent retries as debug to reduce noise
+        if (retryCount === 1) {
+          this.log.warn(
+            `${retryMessage} (subsequent retries will be logged at DEBUG level)`,
+          );
+        } else {
+          this.log.debug(retryMessage);
+        }
+      },
+      onMaxRetryTimesExceeded: (error, retryCount) => {
+        // Get request details to use in error log
+        const config = error.config || {};
+        const axiosConfig = config as AxiosRequestConfig;
+        const url = axiosConfig.url?.split('?')[0] || 'unknown URL';
+        const method = axiosConfig.method?.toUpperCase() || 'unknown method';
+
+        this.log.warn(
+          `Request failed permanently after ${retryCount} retries: ${method} ${url} - ` +
+            `Error: ${error.code || 'unknown'} - ${error.message}`,
+        );
+      },
     });
     return instance;
   }
@@ -364,7 +425,9 @@ export default class Client {
       return;
     }
 
+    this.initialized = true;
     this.eventBus.emit(Event.READY);
+    infoSDKInitOK(this.log);
   }
 
   private async run(): Promise<void> {
@@ -420,8 +483,6 @@ export default class Client {
     }
 
     this.log.info('finished setting up processors');
-    this.initialized = true;
-    infoSDKInitOK(this.log);
   }
 
   boolVariation(

Diff for: src/client.ts

@@ -45,6 +45,7 @@ export const defaultOptions: Options = {
   store: new FileStore(),
   logger: new ConsoleLog(),
   axiosTimeout: 30000,
+  axiosRetries: 3,
 };
 
 const TARGET_SEGMENT_RULES_QUERY_PARAMETER = 'v2';

Diff for: src/constants.ts

@@ -80,7 +80,7 @@ export class PollingProcessor {
         }
       })
       .catch((error) => {
-        this.eventBus.emit(PollerEvent.ERROR, { error });
+        this.eventBus.emit(PollerEvent.ERROR, error);
       })
       .finally(() => {
         // we will check one more time if processor is stopped
@@ -105,7 +105,9 @@ export class PollingProcessor {
         this.repository.setFlag(fc.feature, fc),
       );
     } catch (error) {
-      this.log.error('Error loading flags', error);
+      this.log.error(
+        `Error loading flags (${error.code ?? "UNKNOWN"}): ${error.message}`
+      );
       throw error;
     }
   }
@@ -124,7 +126,9 @@ export class PollingProcessor {
         this.repository.setSegment(segment.identifier, segment),
       );
     } catch (error) {
-      this.log.error('Error loading segments', error);
+      this.log.error(
+        `Error loading segments (${error.code ?? "UNKNOWN"}): ${error.message}`
+      );
       throw error;
     }
   }

Diff for: src/polling.ts

@@ -14,6 +14,7 @@ export interface Options {
   logger?: Logger;
   tlsTrustedCa?: string;
   axiosTimeout?: number;
+  axiosRetries?: number;
 }
 
 export interface APIConfiguration {

Diff for: src/types.ts

@@ -1 +1 @@
-export const VERSION = '1.8.4';
+export const VERSION = '1.8.5';