feat: better rate limit errors

backend/src/lib/errors/index.ts

@@ -71,6 +71,13 @@ export class BadRequestError extends Error {
   }
 }
 
+export class RateLimitError extends Error {
+  constructor({ message }: { message?: string }) {
+    super(message || "Rate limit exceeded");
+    this.name = "RateLimitExceeded";
+  }
+}
+
 export class NotFoundError extends Error {
   name: string;
 

backend/src/server/config/rateLimiter.ts

@@ -2,6 +2,7 @@ import type { RateLimitOptions, RateLimitPluginOptions } from "@fastify/rate-lim
 import { Redis } from "ioredis";
 
 import { getConfig } from "@app/lib/config/env";
+import { RateLimitError } from "@app/lib/errors";
 
 export const globalRateLimiterCfg = (): RateLimitPluginOptions => {
   const appCfg = getConfig();
@@ -10,6 +11,11 @@ export const globalRateLimiterCfg = (): RateLimitPluginOptions => {
     : null;
 
   return {
+    errorResponseBuilder: (_, context) => {
+      throw new RateLimitError({
+        message: `Rate limit exceeded. Please try again in ${context.after}`
+      });
+    },
     timeWindow: 60 * 1000,
     max: 600,
     redis,

backend/src/server/plugins/error-handler.ts

@@ -10,6 +10,7 @@ import {
   GatewayTimeoutError,
   InternalServerError,
   NotFoundError,
+  RateLimitError,
   ScimRequestError,
   UnauthorizedError
 } from "@app/lib/errors";
@@ -27,7 +28,8 @@ enum HttpStatusCodes {
   Forbidden = 403,
   // eslint-disable-next-line @typescript-eslint/no-shadow
   InternalServerError = 500,
-  GatewayTimeout = 504
+  GatewayTimeout = 504,
+  RateLimitExceeded = 429
 }
 
 export const fastifyErrHandler = fastifyPlugin(async (server: FastifyZodProvider) => {
@@ -69,6 +71,12 @@ export const fastifyErrHandler = fastifyPlugin(async (server: FastifyZodProvider
         message: error.message,
         error: error.name
       });
+    } else if (error instanceof RateLimitError) {
+      void res.status(HttpStatusCodes.RateLimitExceeded).send({
+        statusCode: HttpStatusCodes.RateLimitExceeded,
+        message: error.message,
+        error: error.name
+      });
     } else if (error instanceof ScimRequestError) {
       void res.status(error.status).send({
         schemas: error.schemas,