Most application deployments can be a mess; multiple deployments—a production site, multiple test beds, staging environment, and who knows how many development environments are maintained locally by the developers. Additionally, there can be thousands of deployments for the most popular standardized open source packages. This poses a huge challenge for using configuration information of your application that might change depending on the environment one is working with. Even though the source code being run is the same, almost every time the configuration comprises of a large chunk of information that is environment specific. Typical examples include user credentials, database configuration, and so on. The use of property files is quite common to support such a requirement. However, such an approach has its pitfalls as property files quickly replicate themselves quite unmanageably.

Heroku provides a rich CLI-based configuration related API to manage application...