Configuration

This section explains configuration as a core concept in Terramate.

Introduction

Terramate follows the "everything as code" principle, meaning you can fully configure Terramate with code.

Terramate uses Hashicorp Configuration Language (HCL) as its configuration language by extending HCL with Terramate-specific language constructs such as the terramate, stack, generate_hcl or globals blocks that allow you to configure Terramate features such as Stacks, Orchestration, Code Generation, and Variables.

Why HCL

HCL is a structured configuration language rather than a data structure serialization language. It means that, unlike languages such as JSON, YAML, or TOML, HCL gets decoded using an application-defined schema.

In a nutshell:

• HCL allows you to define, compute and reuse configurations easily.
• Terramate builds on top of HCL by adding Terramate-specific language constructs to HCL.
• Terramate provides a great developer experience by providing a language server and IDE plugins.
• Using HCL enables you to use all Terraform and OpenTofu functions such as upper or regex prefixed with tm_ at any place in your Terramate project.

Developer Experience

Terramate provides a language server and several IDE plugins to provide the best developer experience possible while working with Terramate. For details, please see the installation guide.

Why not YAML, JSON, etc.

Most traditional configuration languages are static and do not support variable or function calls for static configuration management. HCL comes with variables and functions built-in, allowing users to easily reuse and compute configuration. For example, in Terramate, you can use all available Terraform functions prefixed with _tm out of the box.