Terraform AWS subnet_id列表被视为ec2实例的单值字符串

Question

我有创建VPC的代码，其中包含2个私有子网，2xec2私有实例和公共堡垒。

ec2代码使用VPC模块subnet_ids的outputs.tf。 由于有2个私有子网，因此将生成2个subnet_id。 当将这些生成的subnet_id而不是一个subnet_id馈入ec2实例时，它将一次作为单个值馈入2个subnet_id。

结果是terraform无法找到subnet_ids的值，创建失败。

错误：子网ID'subnet-0 ***********，subnet-0 *************'不存在

编辑子网* vpc.tf

private_subnets     = "10.10.20.#/#,10.10.20.#/#"

instanceec2.tf

subnet_id           = "${module.vpc.private_subnets}"

以下是模块：

vpc_main.tf

// Private subnet/s
resource "aws_subnet" "private" {
  vpc_id            = "${aws_vpc.vpc.id}"
  cidr_block        = "${element(split(",", var.private_subnets), count.index)}"
  availability_zone = "${element(split(",", var.azs), count.index)}"
  count             = "${length(split(",", var.private_subnets))}"

  tags {
    Name        = "${var.name}-private-${element(split(",", var.azs), count.index)}"
    Team        = "${var.team}"
    Environment = "${var.environment}"
    Service     = "${var.service}"
    Product     = "${var.product}"
    Owner       = "${var.owner}"
    Description = "${var.description}"
    managed_by  = "terraform"
  }
}

resource "aws_route_table" "private" {
  vpc_id = "${aws_vpc.vpc.id}"
  count  = "${length(split(",", var.private_subnets))}"

  tags {
    Name        = "${var.name}-private-${element(split(",", var.azs), count.index)}"
    Team        = "${var.team}"
    Environment = "${var.environment}"
    Service     = "${var.service}"
    Product     = "${var.product}"
    Owner       = "${var.owner}"
    Description = "${var.description}"
    managed_by  = "terraform"
  }
}

resource "aws_route_table_association" "private" {
  subnet_id      = "${element(aws_subnet.private.*.id, count.index)}"
  route_table_id = "${element(aws_route_table.private.*.id, count.index)}"
  count          = "${length(split(",", var.private_subnets))}"
}
``````


vpc_outputs.tf

```````

output "private_subnets" {
  value = "${join(",", aws_subnet.private.*.id)}"
}

期望值只是一个子网ID作为值：

错误：提供2个子网ID作为一个值。

aws_instance.ec2-instance [0]：发生1个错误：

• aws_instance.ec2-instance.0：启动源实例时出错：InvalidSubnetID.NotFound：子网ID'subnet-0 **********，subnet-0 ***********'不存在

Answer 1

由于您已“加入”结果，因此，如果只需要一个子网值，就必须再次拆分。 就像是：

element(split(",", var.private_subnets), 0) 

Answer 2

您在输出变量中加入了子网ID：

output "private_subnets" {
  value = "${join(",", aws_subnet.private.*.id)}"
}

当您从instanceec2.tf访问此输出值时，您将仅收到此连接的ID字符串。 因此，您必须像以前一样再次滑动接收的值，并使用您的ec2资源的计数索引访问各自的ID：

resource "aws_instance" "default" {
    count     = "${length(split(",", module.vpc.private_subnets))}"
    subnet_id = "${element(split(",", module.vpc.private_subnets), count.index)}"
    ....
}    

那应该解决您的问题。

另外，您也可以直接将子网ID作为列表输出：

output "private_subnets" {
  description = "The IDs of the private subnets as list"
  value       = ["${aws_subnet.private.*.id}"]
}

然后使用以下命令访问它们：

subnet_id = "${element(module.vpc.private_subnets, count.index)}"