Infrastructure as Code (IaC) is a practice of managing and provisioning infrastructure through machine-readable definition files. Its key principles include idempotence, which ensures that applying a configuration multiple times yields the same result, and versioning, where infrastructure definitions are stored in version control to track changes and enable collaboration. The configuration files are also self-describing, acting as documentation for the infrastructure's desired state.

A "golden image" is a pre-configured machine image template. While it is a common pattern in infrastructure management and can be deployed using IaC tools like Terraform, it is a specific implementation technique, not a foundational principle of IaC itself.

A. Self-describing infrastructure: IaC configuration files explicitly declare the desired state of all resources, serving as clear, human-readable documentation.

B. Idempotence: This is a core concept in IaC. It guarantees that operations are repeatable and will converge on the same desired state without causing unintended side effects.

C. Versioned infrastructure: Storing IaC files in a version control system (like Git) is a fundamental practice that enables auditing, rollbacks, and collaborative workflows.

1. HashiCorp Developer - What is Infrastructure as Code?: "IaC allows you to manage your infrastructure with a configuration file... This provides a single source of truth for your infrastructure, making it self-documenting." This supports option A. The page also emphasizes version control, supporting option C.

Source: HashiCorp Learn, Introduction to Terraform, "What is Infrastructure as Code?".

2. HashiCorp Developer - Custom Conditions: "Terraform's goal is to be idempotent... Terraform achieves this by saving the state of your infrastructure and comparing it to the state you define in your configuration files." This directly supports idempotence (option B) as a core goal.

Source: HashiCorp Terraform Documentation, Language, Expressions, "Custom Conditions - Idempotence".

3. HashiCorp Resources - What is Immutable Infrastructure?: This resource distinguishes between infrastructure patterns. While golden images can be part of an immutable strategy (a pattern often used with IaC), the concept itself is a building block, not a principle of the IaC methodology. The principles are about how you manage definitions (code, versioning, idempotence), not what you deploy.

Source: HashiCorp Resources, "What is Immutable Infrastructure?".