This repository implements an API Gateway based on Openresty and NGINX with LuaJIT for high-performance request processing. The system provides service discovery via Marathon integration, API key validation, HMAC/OAuth authentication, rate limiting, request/response transformation, and metrics collection. Architecture-wise, it uses a modular design with NGINX configuration files defining request processing phases, Lua modules for extensible functionality (validation, tracking, metrics), and external dependencies for service discovery (Marathon), caching (Redis), and metrics reporting (StatsD). Key entry points include the health-check endpoint (/health-check), metrics endpoint (/api-gateway-stats), and admin API (/tracking/* on port 5000). The gateway processes client requests through validation phases, proxies them to backend services, collects metrics throughout, and returns responses while supporting dynamic configuration reloading and remote config sync from S3.