I'm happy to announce a new project to intergrate Let's Encrypt with OpenResty:
This project runs a pure Lua implementation of ACMEv2 procotol and an FFI-based OpenSSL backend, meaning the library is dependency free other than Lua libraries.
Simply install using
opm install fffonion/lua-resty-acme
The project has full daily end-to-end test suite running, and there're couple of work in the roadmap that looking for help if you are interested!