From 2924fa7abea5bc90284bf8c3aa421f8402a30fe9 Mon Sep 17 00:00:00 2001
From: claimundefine <juswang@confluent.io>
Date: Wed, 4 Dec 2024 13:50:57 -0500
Subject: [PATCH] Add singleton principle to RestService

---
 schemaregistry/package.json                   |  1 +
 schemaregistry/rest-service.ts                | 19 +++++++++++++++----
 .../dekregistry/dekregistry-client.ts         |  2 +-
 schemaregistry/schemaregistry-client.ts       |  2 +-
 4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/schemaregistry/package.json b/schemaregistry/package.json
index ca98bc95..cd310f20 100644
--- a/schemaregistry/package.json
+++ b/schemaregistry/package.json
@@ -59,6 +59,7 @@
   "scripts": {
     "lint": "make lint",
     "test": "make test",
+    "integtest": "make integtest",
     "build": "rm -rf ./dist && tsc -p tsconfig-build.json"
   },
   "keywords": [
diff --git a/schemaregistry/rest-service.ts b/schemaregistry/rest-service.ts
index 7e5876c0..45a263ac 100644
--- a/schemaregistry/rest-service.ts
+++ b/schemaregistry/rest-service.ts
@@ -51,14 +51,15 @@ export interface ClientConfig {
 const toBase64 = (str: string): string => Buffer.from(str).toString('base64');
 
 export class RestService {
+  private static instance: RestService;
   private client: AxiosInstance;
   private baseURLs: string[];
   private oauthClient?: OAuthClient;
   private oauthBearer: boolean = false;
 
   constructor(baseURLs: string[], isForward?: boolean, axiosDefaults?: CreateAxiosDefaults,
-              basicAuthCredentials?: BasicAuthCredentials, bearerAuthCredentials?: BearerAuthCredentials,
-              maxRetries?: number, retriesWaitMs?: number, retriesMaxWaitMs?: number) {
+    basicAuthCredentials?: BasicAuthCredentials, bearerAuthCredentials?: BearerAuthCredentials,
+    maxRetries?: number, retriesWaitMs?: number, retriesMaxWaitMs?: number) {
     this.client = axios.create(axiosDefaults);
     axiosRetry(this.client, {
       retries: maxRetries ?? 2,
@@ -80,6 +81,16 @@ export class RestService {
     this.handleBearerAuth(maxRetries ?? 2, retriesWaitMs ?? 1000, retriesMaxWaitMs ?? 20000, bearerAuthCredentials);
   }
 
+  static getInstance(baseURLs: string[], isForward?: boolean, axiosDefaults?: CreateAxiosDefaults,
+    basicAuthCredentials?: BasicAuthCredentials, bearerAuthCredentials?: BearerAuthCredentials,
+    maxRetries?: number, retriesWaitMs?: number, retriesMaxWaitMs?: number): RestService {
+    if (!this.instance) {
+      this.instance = new RestService(baseURLs, isForward, axiosDefaults, basicAuthCredentials, bearerAuthCredentials,
+        maxRetries, retriesWaitMs, retriesMaxWaitMs);
+    }
+    return this.instance;
+  }
+
   handleBasicAuth(basicAuthCredentials?: BasicAuthCredentials): void {
     if (basicAuthCredentials) {
       switch (basicAuthCredentials.credentialsSource) {
@@ -111,7 +122,7 @@ export class RestService {
     }
   }
 
-  handleBearerAuth(maxRetries: number, 
+  handleBearerAuth(maxRetries: number,
     retriesWaitMs: number, retriesMaxWaitMs: number, bearerAuthCredentials?: BearerAuthCredentials): void {
     if (bearerAuthCredentials) {
       delete this.client.defaults.auth;
@@ -150,7 +161,7 @@ export class RestService {
           }
           const issuerEndPointUrl = new URL(bearerAuthCredentials.issuerEndpointUrl!);
           this.oauthClient = new OAuthClient(bearerAuthCredentials.clientId!, bearerAuthCredentials.clientSecret!,
-            issuerEndPointUrl.origin, issuerEndPointUrl.pathname, bearerAuthCredentials.scope!, 
+            issuerEndPointUrl.origin, issuerEndPointUrl.pathname, bearerAuthCredentials.scope!,
             maxRetries, retriesWaitMs, retriesMaxWaitMs);
           break;
         default:
diff --git a/schemaregistry/rules/encryption/dekregistry/dekregistry-client.ts b/schemaregistry/rules/encryption/dekregistry/dekregistry-client.ts
index 891bdbd7..217631c0 100644
--- a/schemaregistry/rules/encryption/dekregistry/dekregistry-client.ts
+++ b/schemaregistry/rules/encryption/dekregistry/dekregistry-client.ts
@@ -70,7 +70,7 @@ class DekRegistryClient implements DekClient {
     };
 
 
-    this.restService = new RestService(config.baseURLs, config.isForward, config.createAxiosDefaults,
+    this.restService = RestService.getInstance(config.baseURLs, config.isForward, config.createAxiosDefaults,
       config.basicAuthCredentials, config.bearerAuthCredentials,
       config.maxRetries, config.retriesWaitMs, config.retriesMaxWaitMs);
     this.kekCache = new LRUCache<string, Kek>(cacheOptions);
diff --git a/schemaregistry/schemaregistry-client.ts b/schemaregistry/schemaregistry-client.ts
index e323cbbc..fc7dfa90 100644
--- a/schemaregistry/schemaregistry-client.ts
+++ b/schemaregistry/schemaregistry-client.ts
@@ -201,7 +201,7 @@ export class SchemaRegistryClient implements Client {
       ...(config.cacheLatestTtlSecs !== undefined && { ttl: config.cacheLatestTtlSecs * 1000 })
     };
 
-    this.restService = new RestService(config.baseURLs, config.isForward, config.createAxiosDefaults,
+    this.restService = RestService.getInstance(config.baseURLs, config.isForward, config.createAxiosDefaults,
       config.basicAuthCredentials, config.bearerAuthCredentials,
       config.maxRetries, config.retriesWaitMs, config.retriesMaxWaitMs);