Lua

At Kong while building an internal tool, we struggled to route metrics to Prometheus and logs to Logstash without incurring too much latency in our metrics collection.

We replaced NGINX with OpenResty on the edge of our tool which allowed us to use the lua-nginx-module to run Lua code that captures metrics and records telemetry data during every request’s log phase. Our code then pushes the metrics to a local aggregator process (written in Golang) which in turn exposes them in Prometheus Exposition Format for consumption by Prometheus. This solution reduced the number of components we needed to maintain and is fast thanks to NGINX and LuaJIT.

Kong is built on OpenResty because it allows us to extend NGINX with Lua scripts through the ngx_lua module. OpenResty bundles this module as well as many others, providing a powerful server for developers to extend.

We could have built a modular reverse proxy on NGINX either by bundling Nginx with our own flavor of 3rd party modules or by developing on top of OpenResty. We admired the work done on OpenResty and thought of a way to build a modulable core, on which plugins could be added. Hence, Kong is mostly a collection of Lua scripts that allow it to execute plugins at runtime for routes and services.

This decision is an adaptation of a Quora answer originally written by Thibault Charbonnier.

used lua as gameplay glue while at insomniac. one my favorite wins was integrating table support. it took walking the source code in a debugger to figure it out, still remember being at work at 3am when i got it working finally. (no google back then to make such things simple.) Lua

Lua is used as the programming language for all extensions and the main business logic. Lua