How are variables passed into Terraform configurations?

Variables in Terraform configurations are primarily passed using input variables, which can be declared within the configuration files and then filled in through .tfvars files or command line arguments when running Terraform commands. Input variables allow for flexibility and reusability in your infrastructure code, enabling configurations to adapt based on different environments or requirements without modifying the core configurations themselves.

Using .tfvars files, you can define variable values in a structured format, which Terraform automatically loads when applied. Alternatively, these values can be set directly via command line flags, allowing for dynamic or one-off overrides without needing to alter the configuration files or separate variable files.

This method provides a robust way to manage configuration parameters, ensuring that values can be modified easily without changing the actual code, which promotes better practices in version control and collaboration. It also helps avoid hardcoding values directly in the configuration, which can lead to challenges in maintainability and scaling.

In contrast, relying solely on environment variables limits the scope of where you can define and organize your inputs, while JSON files represent a less common practice specifically for variable management, and hardcoding values can significantly hinder reusability and adaptability of the code.