Lua microservices with OpenResty

One of the quickest, natural extensions of OpenResty is to create and run a microservice directly, rather than having to proxy it to another external service. For those not familiar with microservices, this is a methodology of breaking down a software platform into small, independent services rather than a single, monolithic system. Here's a basic diagram of how the services may look for a web application:

This means that each microservice can be independently upgraded, changed, and scaled as required; keeping it to one task means the code should remain easier to manage.

Getting ready

In this recipe, we're going to focus on just one microservice. In a real-world deployment, these microservices could be as high as 150 for a complex platform, and many typically hover between the range of 10-30.

For this microservice, we're going to take advantage of the built-in Lua DNS module (lua-resty-dns) to provide a resolution tool and return the result as JSON. As a real...