BUY-3414 Rate Limit Audit Report

Issue: BUY-3414 Load test /v1/products/search and /v1/auth/register at 10x traffic Date: 2026-04-19 Agent: Atlas (QA Lead) Status: Audit Complete - Critical Issues Found

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Executive Summary

The load test design for BUY-3414 has 3 critical blockers that prevent execution at 10x traffic:

1. Search rate limit is 200-300x too restrictive - Will cause 100% rate limit failures
2. /v1/auth/register endpoint does not exist - Fixed to use /v1/developers/signup
3. Developer signup has 5/hour limit - Cannot be load tested at scale (by design)

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Rate Limit Architecture

Layer 1: Cloudflare Edge (cloudflare/rate-limit.json)

Layer 2: Application - SlowAPI (app/rate_limit.py)

Layer 3: Endpoint-Specific (decorators)

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Critical Issues

Issue 1: Search Rate Limit is 200-300x Too Restrictive

Current state:

• Cloudflare: 30 requests/minute per client
• Application: 100-150 requests/minute per client

10x traffic scenario:

• 10,000 VUs
• 85% hitting search endpoint = 8,500 concurrent search requests
• Current capacity: 30-150 requests/minute per client

Expected result: 99%+ of requests will be rate limited (429 response)

Recommendation: Increase Cloudflare buywhere_search_rate_limit to 300 requests/minute for authenticated users.

Issue 2: /v1/auth/register Does Not Exist

Problem: Issue BUY-3414 references /v1/auth/register which is not implemented in the codebase.

Actual endpoints:

• /v1/developers/signup - Developer API key registration (5/hour limit)
• /api/auth/signup - User account registration for price alerts (10/hour limit)

Fix applied: Updated load_test_buy3414_k6.js to use /v1/developers/signup

Issue 3: Developer Signup Cannot Be Load Tested at Scale

Current limit: 5 registrations per hour per IP

Why: This is intentional to prevent spam and abuse during developer onboarding.

Implication: The auth/register load test scenario in the k6 script will fail at even modest VUs (e.g., 100 VUs hitting 5% of traffic = 5 registrations/min = 300/hour, way over the 5/hour limit).

Recommendation: Use pre-provisioned API keys for auth load testing instead of registering new accounts.

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Load Test Script Fixes

Fixed: /v1/auth/register → /v1/developers/signup

Before:

http.post(`${BASE_URL}/v1/auth/register`, {
  email: email,
  password: 'LoadTest123!',
  developer_name: 'LoadTest Agent',
})

After:

http.post(`${BASE_URL}/v1/developers/signup`, {
  email: email,
  name: 'LoadTest Agent',
  experiment_variant: 'a',
})

Script Location

/home/paperclip/buywhere-api/load_test_buy3414_k6.js

To Run

# Install k6 (if not installed)
curl -sL https://github.com/grafana/k6/releases/download/v0.54.0/k6-v0.54.0-linux-amd64.tar.gz | tar xz
sudo mv k6 /usr/local/bin/

# Run load test (against production - WARNING: will cause rate limits)
k6 run load_test_buy3414_k6.js

# Run with custom config
BASE_URL=https://api.buywhere.ai API_KEY=bw_your_key k6 run load_test_buy3414_k6.js

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Recommendations

Immediate (for 10x traffic test to succeed)

1. Increase Cloudflare search rate limit to 300 req/min for authenticated users

   {
     "id": "buywhere_search_rate_limit",
     "rate_limit": {
       "requests_per_period": 300,
       "period_sec": 60,
       "concurrent_requests": 30,
       "mitigation_timeout": 180
     }
   }
   

2. Use pre-provisioned API keys for auth load testing

   • Remove the registerAuth scenario from the k6 script
   • Or create a separate test key with higher limits

3. Separate search and auth tests into distinct runs

   • Search: 10,000 VUs, 85% search, 10% product detail, 5% other
   • Auth: 1,000 VUs max (due to 5/hour signup limit)

Long-term

1. Add rate limit headers to distinguish Cloudflare vs SlowAPI limits

   • Cloudflare returns: CF-Cache-Status, Retry-After
   • SlowAPI returns: X-RateLimit-Limit, X-RateLimit-Remaining

2. Consider dedicated rate limits for AI agents

   • Agents make many repeated queries (cached results OK)
   • Could have higher limits with caching

3. Implement /v1/auth/register if intended endpoint

   • Currently undefined in issue - confirm with backend team

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Files Modified

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Test Execution Commands

Pre-flight (verify endpoints exist)

# Test search endpoint
curl -H "Authorization: Bearer $API_KEY" \
     "https://api.buywhere.ai/v1/products/search?q=test&limit=10"

# Test developer signup
curl -X POST "https://api.buywhere.ai/v1/developers/signup" \
     -H "Content-Type: application/json" \
     -d '{"email":"test@example.com","name":"Test"}'

Run k6 Load Test

# Full 10x traffic test
k6 run load_test_buy3414_k6.js

# Dry run (10 VUs only)
k6 run --vus 10 --duration 30s load_test_buy3414_k6.js

Expected Output

• load_test_buy3414_results.json - JSON metrics
• stdout - Human-readable summary