1. 使用公有模块

https://registry.terraform.io/browse/modules

引用了（ https://registry.terraform.io/modules/matti/resource/shell/latest ）这个模块：

module "echo-larry-result" {
  source  = "matti/resource/shell"
  version = "1.5.0"
  command = "cat ${module.larry-file.file_name}"
}

module "echo-larry-result" {
  source  = "matti/resource/shell"
  version = "1.5.0"
  command = "cat ${module.larry-file.file_name}"
}

执行terraform get会从仓库下载模块：

$ terraform get
Downloading matti/resource/shell 1.5.0 for echo-larry-result...
- echo-larry-result in .terraform/modules/echo-larry-result
- larry-file in random-file
- pkslow-file in random-file

$ terraform get
Downloading matti/resource/shell 1.5.0 for echo-larry-result...
- echo-larry-result in .terraform/modules/echo-larry-result
- larry-file in random-file
- pkslow-file in random-file