lua-resty-auto-ssl is an OpenResty (nginx + Lua) plugin that automatically issues and renews SSL/TLS certificates from Let's Encrypt (ACME) on the fly. It intercepts the SSL handshake via ssl_certificate_by_lua, checks for existing certificates in shared memory or persistent storage (file or Redis), and if missing, triggers certificate issuance using the dehydrated shell client. Domain validation is handled automatically via HTTP-01 challenges. The plugin supports multiple nginx workers, distributed storage, OCSP stapling, and configurable domain allow/deny policies. It is designed for high-traffic production environments but has been explicitly abandoned by its maintainers, with no active development since 2019. The codebase is well-structured with modular storage adapters, JSON adapters, and locking mechanisms, but relies on external shell processes (sockproc) and the dehydrated script, making it difficult to maintain and prone to issues with modern Let's Encrypt API changes. Given its abandoned status, it is not recommended for new projects; users should consider alternatives like acme.sh, acme-companion, or win-acme.