aws_route_table_association与多个子网在运行时(AWS)

Question

我正在尝试为公共子网创建aws_route_table_association资源。公共子网的数量将在运行时确定，因此将确定要创建的关联的数量。

在执行地形计划时，我的代码失败了。下面是源代码和错误我得到。有谁能给我一些建议吗?

//  required subnets and their configurations
variable "required_subnets" {
description = "list of subnets required"
default     = ["public-1a", "private-1a", "public-1b", "private-1b"]
}
#create public and provate subnets
resource "aws_subnet" "subnets" {
count             = length(var.required_subnets)
vpc_id            = aws_vpc.my_vpc.id
cidr_block        = lookup(var.subnet_conf[var.required_subnets[count.index]], "cidr")
availability_zone = lookup(var.subnet_conf[var.required_subnets[count.index]], "availability_zone")
# enable public ip addresses in public subnet
map_public_ip_on_launch = false
tags = {
Name = var.required_subnets[count.index]
}
}
//fetch reference to public subnets
data "aws_subnets" "public_subnets" {
filter {
name   = "vpc-id"
values = [data.aws_vpc.vpc.id]
}
tags = {
Name = "public-*"
}
}
#assosiate public route table with public subnet
resource "aws_route_table_association" "public" {
count          = length(data.aws_subnets.public_subnets.ids)
subnet_id      = data.aws_subnets.public_subnets.ids[count.index]
route_table_id = aws_route_table.my_public_route_table.id
}

错误如下:

│ Error: Invalid count argument
│
│   on vpc.tf line 62, in resource "aws_route_table_association" "public":
│   62:   count          = length(data.aws_subnets.public_subnets.ids)
│
│ The "count" value depends on resource attributes that cannot be determined until apply, so Terraform cannot predict how    
│ many instances will be created. To work around this, use the -target argument to first apply only the resources that the   
│ count depends on.

Answer 1

如果您只需要required_subnets，那么您的data.aws_subnets.public_subnets就没有理由了。此外，最好使用for_each，而不是count，因为for_each不依赖于项目的顺序。因此，您可以简单地按照如下方式编写代码:

//  required subnets and their configurations
variable "required_subnets" {
description = "list of subnets required"
default     = ["public-1a", "private-1a", "public-1b", "private-1b"]
}
#create public and provate subnets
resource "aws_subnet" "subnets" {
for_each          = toset(var.required_subnets)
vpc_id            = aws_vpc.my_vpc.id
cidr_block        = lookup(var.subnet_conf[each.key], "cidr")
availability_zone = lookup(var.subnet_conf[each.key], "availability_zone")
# enable public ip addresses in public subnet
map_public_ip_on_launch = false
tags = {
Name = each.key
}
}
#assosiate public route table with public subnet
resource "aws_route_table_association" "public" {
for_each       = {for name, subnet in aws_subnet.subnets: name => subnet if length(regexall("public-", name)) > 0}   
subnet_id      = each.value.id
route_table_id = aws_route_table.my_public_route_table.id
}