feat(client): add support for endpoint-specific base URLs

Author: stainless-app[bot]

package.json

@@ -45,7 +45,7 @@
     "publint": "^0.2.12",
     "ts-jest": "^29.1.0",
     "ts-node": "^10.5.0",
-    "tsc-multi": "https://github.com/stainless-api/tsc-multi/releases/download/v1.1.7/tsc-multi.tgz",
+    "tsc-multi": "https://github.com/stainless-api/tsc-multi/releases/download/v1.1.8/tsc-multi.tgz",
     "tsconfig-paths": "^4.0.0",
     "typescript": "5.8.3",
     "ws": "^8.18.0",

src/client.ts

@@ -372,6 +372,13 @@ export class OpenAI {
     });
   }
 
+  /**
+   * Check whether the base URL is set to its default.
+   */
+  #baseURLOverridden(): boolean {
+    return this.baseURL !== 'https://api.openai.com/v1';
+  }
+
   protected defaultQuery(): Record<string, string | undefined> | undefined {
     return this._options.defaultQuery;
   }
@@ -405,11 +412,16 @@ export class OpenAI {
     return Errors.APIError.generate(status, error, message, headers);
   }
 
-  buildURL(path: string, query: Record<string, unknown> | null | undefined): string {
+  buildURL(
+    path: string,
+    query: Record<string, unknown> | null | undefined,
+    defaultBaseURL?: string | undefined,
+  ): string {
+    const baseURL = (!this.#baseURLOverridden() && defaultBaseURL) || this.baseURL;
     const url =
       isAbsoluteURL(path) ?
         new URL(path)
-      : new URL(this.baseURL + (this.baseURL.endsWith('/') && path.startsWith('/') ? path.slice(1) : path));
+      : new URL(baseURL + (baseURL.endsWith('/') && path.startsWith('/') ? path.slice(1) : path));
 
     const defaultQuery = this.defaultQuery();
     if (!isEmptyObj(defaultQuery)) {
@@ -773,9 +785,9 @@ export class OpenAI {
     { retryCount = 0 }: { retryCount?: number } = {},
   ): { req: FinalizedRequestInit; url: string; timeout: number } {
     const options = { ...inputOptions };
-    const { method, path, query } = options;
+    const { method, path, query, defaultBaseURL } = options;
 
-    const url = this.buildURL(path!, query as Record<string, unknown>);
+    const url = this.buildURL(path!, query as Record<string, unknown>, defaultBaseURL);
     if ('timeout' in options) validatePositiveInteger('timeout', options.timeout);
     options.timeout = options.timeout ?? this.timeout;
     const { bodyHeaders, body } = this.buildBody({ options });

src/internal/request-options.ts

@@ -21,6 +21,7 @@ export type RequestOptions = {
   fetchOptions?: MergedRequestInit;
   signal?: AbortSignal | undefined | null;
   idempotencyKey?: string;
+  defaultBaseURL?: string | undefined;
 
   __metadata?: Record<string, unknown>;
   __binaryResponse?: boolean | undefined;

tests/index.test.ts

@@ -310,6 +310,28 @@ describe('instantiate client', () => {
       const client = new OpenAI({ apiKey: 'My API Key' });
       expect(client.baseURL).toEqual('https://api.openai.com/v1');
     });
+
+    test('in request options', () => {
+      const client = new OpenAI({ apiKey: 'My API Key' });
+      expect(client.buildURL('/foo', null, 'http://localhost:5000/option')).toEqual(
+        'http://localhost:5000/option/foo',
+      );
+    });
+
+    test('in request options overridden by client options', () => {
+      const client = new OpenAI({ apiKey: 'My API Key', baseURL: 'http://localhost:5000/client' });
+      expect(client.buildURL('/foo', null, 'http://localhost:5000/option')).toEqual(
+        'http://localhost:5000/client/foo',
+      );
+    });
+
+    test('in request options overridden by env variable', () => {
+      process.env['OPENAI_BASE_URL'] = 'http://localhost:5000/env';
+      const client = new OpenAI({ apiKey: 'My API Key' });
+      expect(client.buildURL('/foo', null, 'http://localhost:5000/option')).toEqual(
+        'http://localhost:5000/env/foo',
+      );
+    });
   });
 
   test('maxRetries option is correctly set', () => {

yarn.lock

@@ -3302,9 +3302,9 @@ ts-node@^10.5.0:
     v8-compile-cache-lib "^3.0.0"
     yn "3.1.1"
 
-"tsc-multi@https://github.com/stainless-api/tsc-multi/releases/download/v1.1.7/tsc-multi.tgz":
-  version "1.1.7"
-  resolved "https://github.com/stainless-api/tsc-multi/releases/download/v1.1.7/tsc-multi.tgz#52f40adf8b808bd0b633346d11cc4a8aeea465cd"
+"tsc-multi@https://github.com/stainless-api/tsc-multi/releases/download/v1.1.8/tsc-multi.tgz":
+  version "1.1.8"
+  resolved "https://github.com/stainless-api/tsc-multi/releases/download/v1.1.8/tsc-multi.tgz#f544b359b8f05e607771ffacc280e58201476b04"
   dependencies:
     debug "^4.3.7"
     fast-glob "^3.3.2"