Test-Driven Infrastructure with Chef

The Principles of Infrastructure as Code

Having explored the origins and rationale for the project of managing Infrastructure as Code, we now turn to the core principles we should put into practice to make it happen.

Adam Jacob, co-founder of Opscode, and creator of Chef argues that, at a high level, there are two steps:

1. Break the infrastructure down into independent, reusable, network-accessible services.

2. Integrate these services in such a way as to produce the functionality your infrastructure requires.

Adam further identifies ten principles that describe what the characteristics of the reusable primitive components look like. His essay is essential reading^[4], but I will summarize his principles here:

Modularity

Our services should be small and simple—think at the level of the simplest freestanding, useful component.

Cooperation

Our design should discourage overlap of services, and should encourage other people and services to use our service in a way which fosters continuous improvement of our design and implementation.

Composability

Our services should be like building blocks—we should be able to build complete, complex systems by integrating them.

Extensibility

Our services should be easy to modify, enhance, and improve in response to new demands.

Flexibility

We should build our services using tools that provide unlimited power to ensure we have the (theoretical) ability to solve even the most complicated of problems.

Repeatability

Our services should produce the same results, in the same ...