Beyond the Twelve-Factor App

Chapter 3. Dependency Management

The second of the original 12 factors, dependencies, refers to the management of application dependencies: how, where, and when they are managed.

Reliance on the Mommy Server

In classic enterprise environments, we’re used to the concept of the mommy server. This is a server that provides everything that our applications need and takes care of their every desire, from satisfying the application’s dependencies to providing a server in which to host the app. The inverse of a mommy server, of course, is the embedded, or bootstrapped,¹ server, where everything we need to run our application is contained within a single build artifact.

The cloud is a maturation of the classic enterprise model, and as such, our applications need to grow up to take advantage of the cloud. Applications can’t assume that a server or application container will have everything they need. Instead, apps need to bring their dependencies with them. Migrating to the cloud, maturing your development practices, means weaning your organization off the need for mommy servers.

If you’ve been building applications in languages or frameworks that don’t rely on the container model (Ruby, Go, Java with Spring Boot, etc.), then you’re already ahead of the game, and your code remains blissfully unaware of containers or mommy servers.

Modern Dependency Management

Most contemporary programming languages have some facility for managing application dependencies. Maven and Gradle are two of ...