Lua CORS Guide: What It Is and How to Enable It

Cross-site request forgery (CSRF) is a significant web security threat that developers need to address, as it can be used by hackers to steal user information from web applications. While limiting web apps to a single domain is a defense strategy, it's not always feasible, making cross-origin resource sharing (CORS) crucial for safely handling cross-domain requests. CORS, a security mechanism implemented by all modern browsers, determines what resources an application can request based on its origin. This post explores how CORS works, its role in preventing CSRF attacks, and how to implement it in Lua applications using platforms like OpenResty and web servers like Nginx and Apache. OpenResty, based on Nginx and Lua, supports CORS through the lua-resty-cors library, which enables configuration of permitted origins and methods while maintaining security. The post advises against using wildcard origins to prevent security vulnerabilities and provides safer configuration practices for both Nginx and Apache to ensure secure cross-origin requests.