Export createRateLimitMiddleware from @backstage/backend-defaults/httpRouter (#32789)

When attempting to follow the directions in the [docs to customize the HTTP router](https://backstage.io/docs/backend-system/core-services/http-router/#configuring-the-service), I found that I could not follow them because `createRateLimitMiddleware` was not exported as the code suggested it should be. This patch exports it.

Signed-off-by: Riley Martine <rmartine@integralads.com>
Co-authored-by: Aramis Sennyey <159921952+aramissennyeydd@users.noreply.github.com>

.changeset/open-cameras-smoke.md

@@ -0,0 +1,5 @@
+---
+'@backstage/backend-defaults': patch
+---
+
+`createRateLimitMiddleware` is now exported from `@backstage/backend-defaults/httpRouter`

packages/backend-defaults/report-httpRouter.api.md

@@ -39,6 +39,12 @@ export function createLifecycleMiddleware(
   options: LifecycleMiddlewareOptions,
 ): RequestHandler;
 
+// @public
+export const createRateLimitMiddleware: (options: {
+  pluginId: string;
+  config: RootConfigService;
+}) => RequestHandler;
+
 // @public
 export const httpRouterServiceFactory: ServiceFactory<
   HttpRouterService,

packages/backend-defaults/src/entrypoints/httpRouter/http/createRateLimitMiddleware.ts

@@ -13,15 +13,20 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { NextFunction, Request, Response } from 'express';
+import { NextFunction, Request, Response, RequestHandler } from 'express';
 import { RateLimitStoreFactory } from '../../../lib/RateLimitStoreFactory.ts';
-import { Config } from '@backstage/config';
+import { RootConfigService } from '@backstage/backend-plugin-api';
+
 import { rateLimitMiddleware } from '../../../lib/rateLimitMiddleware.ts';
 
+/**
+ * @public
+ * Creates a middleware that applies rate limiting to requests based on the provided configuration.
+ */
 export const createRateLimitMiddleware = (options: {
   pluginId: string;
-  config: Config;
-}) => {
+  config: RootConfigService;
+}): RequestHandler => {
   const { pluginId, config } = options;
   const configKey = `backend.rateLimit.plugin.${pluginId}`;
   const enabled = config.has(configKey);

packages/backend-defaults/src/entrypoints/httpRouter/http/index.ts

@@ -18,3 +18,4 @@ export { createCredentialsBarrier } from './createCredentialsBarrier';
 export { createLifecycleMiddleware } from './createLifecycleMiddleware';
 export type { LifecycleMiddlewareOptions } from './createLifecycleMiddleware';
 export { createCookieAuthRefreshMiddleware } from './createCookieAuthRefreshMiddleware';
+export { createRateLimitMiddleware } from './createRateLimitMiddleware';