Modules

Modules in the docs.

A module is a container for multiple resources that are used together.

Basic

module "servers" {
  source = "./app-cluster"

  servers = 5
}

Reference module output.

resource "aws_elb" "example" {
  # ...

  instances = module.servers.instance_ids
}

Module versions

Use a version number when referencing a module that is in a GitHub repo or the Terraform package registry.

module "consul" {
  source  = "hashicorp/consul/aws"
  version = "0.0.5"

  servers = 3
}

Multiple instances of a module

From TF 0.13.

• my_buckets.tf

    module "bucket" {
      for_each = toset(["assets", "media"])
      source   = "./publish_bucket"
      name     = "${each.key}_bucket"
    }
  

• publish_bucket/bucket-and-cloudfront.tf

    variable "name" {} # this is the input parameter of the module
  
    resource "aws_s3_bucket" "example" {
      # Because var.name includes each.key in the calling
      # module block, its value will be different for
      # each instance of this module.
      bucket = var.name
  
      # ...
    }
  
    resource "aws_iam_user" "deploy_user" {
      # ...
    }
  

Providers within submodules

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = ">= 2.7.0"
    }
  }
}