Terraform中aws_route_table引用aws_nat_gateway报错求助

问题根源 #

aws_nat_gateway.private是基于aws_subnet.public的键创建的（键为子网ID或自定义标识），但aws_route_table.private的for_each用了toset(["test", "prod"])，导致用each.key（"test"或"prod"）访问aws_nat_gateway.private时，找不到匹配的键，触发报错。

修正方案 #

根据实际需求选择对应方案：

方案一：路由表与公有子网一一对应

如果每个公有子网的NAT网关对应一个私有路由表，直接将路由表的for_each与NAT网关保持一致：

# Create Route tables and default routes
resource "aws_route_table" "private" {
  for_each = aws_subnet.public
  vpc_id   = aws_vpc.main.id
  route {
    cidr_block     = "0.0.0.0/0"
    nat_gateway_id = aws_nat_gateway.private[each.key].id
  }
}

方案二：保留"test"/"prod"路由表标识

如果确实需要创建名为"test"和"prod"的路由表，需建立环境与公有子网的映射关系，通过子网ID匹配NAT网关：

# 定义环境与公有子网的映射（替换成你的实际子网ID）
variable "subnet_env_map" {
  type = map(string)
  default = {
    "test" = "test-public-subnet-id"
    "prod" = "prod-public-subnet-id"
  }
}

# Create Route tables and default routes
resource "aws_route_table" "private" {
  for_each = var.subnet_env_map
  vpc_id   = aws_vpc.main.id
  route {
    cidr_block     = "0.0.0.0/0"
    nat_gateway_id = aws_nat_gateway.private[each.value].id
  }
}

额外语法修正 #

原代码中aws_eip.nat_gateway_ip存在多余闭合大括号，需修正：

resource "aws_eip" "nat_gateway_ip" {
  for_each = aws_subnet.public
  vpc      = true
}

内容的提问来源于stack exchange，提问作者bitbucket