amazon-ec2 - 如何遍历 terraform 中的所有 aws_instances？

Question

我是 terraform 的新手，我正在尝试遍历所有 aws_instances 以应用 null_resource。您能否使用多个 splat 来访问所有实例，而不管它们的名称？

EC2 实例分为三种类型:

aws_instance.web.* (3 instances)
aws_instance.app.* (3 instances)
aws_instance.db.*  (2 instances)

这是我对所有八个 aws_instances 应用 null_resource 的尝试:

resource "null_resource" "install_security_package" {

  #count = "${length(aws_instance)}" #terraform error: resource count can't reference variable: aws_instance
  #count = "${length(aws_instance.*)}" #terraform error: resource variables must be three parts: TYPE.NAME.ATTR
  count = "${length(aws_instance.*.*)}" #terraform error: unknown resource 'aws_instance.*'

  connection {
    type        = "ssh"
    host        = "${element(aws_instance.*.private_ip, count.index)}"
    user        = "${lookup(var.user, var.platform)}"
    private_key = "${file("${var.private_key_path}")}"
    timeout     = "2m"
  }

  provisioner "remote-exec" {
    inline = [
      "sudo rpm -Uvh http://www.example.com/security/repo/security_baseline.rpm",
    ]
  }
}

Answer 1

目前无法匹配给定类型的所有资源。如您所见，“splat”语法仅允许选择从特定资源 block 创建的所有实例。

今天使用 Terraform 最接近的方法是将不同的资源连接在一起:

concat(aws_instance.web.*.private_ip, aws_instance.app.*.private_ip, aws_instance.db.*.private_ip)

在这个答案的当前版本的 Terraform 中，有必要使用 github issue #4084 中共享的一些解决方法为了避免在多个地方重复那个复杂的表达式。即将推出的功能称为 Local Values将在不久的将来使这更简单，允许为列表命名以在多个地方重复使用:

# Won't work until Terraform PR#15449 is merged and released
locals {
  aws_instance_addrs = "${concat(aws_instance.web.*.private_ip, aws_instance.app.*.private_ip, aws_instance.db.*.private_ip)}"
}

resource "null_resource" "install_security_package" {

  count = "${length(local.aws_instance_addrs)}"

  connection {
    type        = "ssh"
    host        = "${local.aws_instance_addrs[count.index]}"
    user        = "${lookup(var.user, var.platform)}"
    private_key = "${file("${var.private_key_path}")}"
    timeout     = "2m"
  }

  provisioner "remote-exec" {
    inline = [
      "sudo rpm -Uvh http://www.example.com/security/repo/security_baseline.rpm",
    ]
  }
}