How does terraform use modules?

Terraform
1

How does terraform use modules?

For example in the below link there is reference to a module?
source = “innovationnorway/virtual-network/azurerm” what is this path for?

Please explain.

https://registry.terraform.io/modules/innovationnorway/virtual-network/azurerm/1.0.0

There is also module in the upper right of the html page. All it says is to run terraform init. What is the comment to “# insert the 4 required variables here”? What are these 4 variables?

module “virtual-network” {
source = “innovationnorway/virtual-network/azurerm”
version = “1.0.0”

insert the 4 required variables here

}

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

resource "azurerm_resource_group" "example" {
  name     = "example-resources"
  location = "westeurope"
}

module "virtual_network" {
  source = "innovationnorway/virtual-network/azurerm"

  name = "example-network"

  resource_group_name = azurerm_resource_group.example.name

  address_space = ["10.0.0.0/16"]

  subnets = [
    {
      name           = "subnet-1"
      address_prefix = "10.0.1.0/24"
    },
    {
      name           = "subnet-2"
      address_prefix = "10.0.2.0/24"
      delegations    = ["Microsoft.ContainerInstance/containerGroups"]
    },
  ]
}
2

The module source is flexible and can be used to mean one of:

  • Terraform Registry reference
  • relative / fully qualified path on local file system
  • git repository
  • http/https

The example you provded would be interpreted by Terraform as a registry module.
The module sources are described here.

In regards to the 4 required variables, the module you reference takes 6 total possible input variables, but 4 of them do not have a default value, so must be provided (are required) when you invoke the module. The input variables are documented on the Terraform Registry under the Inputs tab:
https://registry.terraform.io/modules/innovationnorway/virtual-network/azurerm/1.0.0?tab=inputs

3

In addition to what @sl1pm4t shared, there’s some general background information on Terraform modules in the documentation section Modules. I think the content on that page should hopefully connect the dots a little; if you have any follow-on questions please do ask!