ngx_mruby is an Nginx module that embeds the mruby lightweight Ruby VM, enabling scripting within Nginx's HTTP and Stream processing phases. The module defines directives such as mruby_set, mruby_rewrite_handler, mruby_access_handler, mruby_content_handler, mruby_header_filter, mruby_body_filter, and stream equivalents, allowing developers to execute Ruby code at each phase of request processing. The repository includes a vendored copy of mruby (version 3.3.0) and the Nginx Devel Kit (NDK) as dependencies, along with numerous mrbgems for extended functionality (e.g., mruby-redis, mruby-json, mruby-fiber). The architecture is a C-based Nginx module that calls mruby's API to compile and execute scripts within Nginx's event loop, with support for coroutine-based asynchronous operations via fibers (Nginx::Async.sleep, Nginx::Async::HTTP.sub_request). The system is designed for high performance and low memory overhead, sharing a single mruby interpreter state across worker processes but clearing global variables between scripts. The codebase includes extensive integration tests, soak tests, performance benchmarks (using valgrind), and fuzzing harnesses, demonstrating a production-grade engineering effort. While the core mruby runtime and NDK are third-party projects included as subtrees, the ngx_mruby module itself provides a clean integration pattern that is reusable for other event-driven server embedding scenarios.