On the Jolicode Blog there's a new post covering something not often mentioned in PHP development: environment variables. In this tutorial the author provides what you "need to know" about these variables and how to more effectively use them in your applications.

Environment variables for configuration are today’s best practice for application setup – database credentials, API Keys, secrets and everything varying between deploys are now exposed to the code via the environment, instead of configuration files or worse, directly hard-coded. Let’s dive into: how does it work, is it really a good idea, how to deal with them in PHP and finally some recommendations and common errors to avoid – with some real world traps we fell into!

They start with a "101" look at environment variables, covering what they are and how they can be referenced from your code (both in the web server and on the command line). They briefly talk about the potential danger in their use and using a .env file to store and read them rather than having them as web server configuration options. The post also includes examples of importing these values using various libraries and some of the common pitfalls that can come with their use.