Standard Structure

Terraform modules should follow a standard structure to make them easier to use and maintain. The following structure is recommended:

ROOT
├── README.md
├── main.tf
├── variables.tf
├── outputs.tf
├── LICENSE
├── modules
│   ├── module1
│   │   ├── README.md
│   │   ├── main.tf
│   │   ├── variables.tf
│   │   └── outputs.tf
│   ├── module2
│   │   ├── main.tf
│   │   ├── variables.tf
│   │   └── outputs.tf
│   │
  • README.md: Contains the documentation of the module and how to use it.
  • main.tf: Contains the resources of the module.
  • variables.tf: Contains the input variables of the module.
  • outputs.tf: Contains the outputs of the module.
  • LICENSE: Contains the license of the module.

Nested modules

Modules can be nested to create more complex modules. For example, a module that creates a VPC can be composed of a module that creates the subnets and a module that creates the routing tables.

  • They should be placed in the modules directory in the root module.
  • If they contain a README.md file, it is deemed as a public module usable by external users. If not, it is deemed as a private module only usable by the root module.
  • Relative paths should be avoided when referencing nested modules.