Viper is a popular configuration library that’s designed with 12 factor applications in mind.
Viper is a complete configuration solution for go applications including 12 factor apps. It is designed to work within an application, and can handle all types of configuration needs and formats. Viper can be thought of as a registry for all of your applications configuration needs.
Let’s use it to provide configuration for a typical application.
Having more than a decade of experience with MySQL, there are a few tricks I picked up over the years that I believe should be in the arsenal of every developer who works with this database more than just superficially. I’m going to list a quick break-down of them from the top of my head.
Being a software engineer, programmer, developer - is not a destination. The good ones have a natural curiosity, where the main measure of an activity is what you learned while doing it. There’s a number of things that people learn - some which can eventually be explained away by documentation. What it logical isn’t always how things are.
A few days ago, I came across an interesting article, Calling Go Functions from Other languages. In it, Vladimir Vivien creates a small shared library in Go, which he then invokes from C, Java using Java Native Access, and from Python, Node, Ruby using Foreign Function Interface libraries. I thought it would be a fun exercise to interface LUA, or more accurately LUAJIT with the library which was written here.
One of the most important 12 Factor Application principles is dictating how your configuration should be declared and passed to your application. If you’re using a database instance, the location and credentials for that database instance should come from the environment where your application is run. This means that it should be passed via an environment variable, via a command line argument, or even via a configuration file which must be passed as a command line argument.
A few months ago I wrote an article on how to clear single cache items from NGINX with LUA, with a simple O(1) complexity. While it’s certainly possible to use it for simple and low-impact cache invalidation, there is a need for deleting huge parts of the cache with a wildcard pattern.
