terraform模块中的可选映射变量

Question

不知道这是否可能，但我有一个DynamoDb表的模块，我想使global_secondary_index属性为可选，但我无法弄清楚如何执行此操作。

我有以下模块

resource "aws_dynamodb_table" "basic_dynamodb_table" { 
    name    = "${var.table_name}" 
    read_capacity  = "${var.read_capacity}" 
    write_capacity  = "${var.write_capacity}" 
    hash_key   = "${var.primary_key}" 

    attribute { 
    name   = "${var.primary_key}" 
    type   = "${var.primary_key_type}" 
    } 

    global_secondary_index = ["${var.global_secondary_index}"] 
} 

variable "table_name" {} 

variable "read_capacity" { 
    default  = "1" 
} 

variable "write_capacity" { 
    default  = "1" 
} 

variable "primary_key" {} 

variable "primary_key_type" {} 

variable "global_secondary_index" { 
    default = {} 
    type = "map" 
    description = "This should be optional" 
} 

而且，它还将被用来

module "test-table" { 
    source    = "./modules/DynamoDb" 

    table_name   = "test-table" 
    primary_key   = "Id" 
    primary_key_type = "S" 

    global_secondary_index = { 
    name = "by-secondary-id" 
    hash_key = "secondaryId" 
    range_key = "type" 
    projection_type = "INCLUDE" 
    non_key_attributes = [ 
     "id" 
    ] 
    write_capacity = 1 
    read_capacity = 1 
    } 
} 

我已经试过：

• 不使用[]周围的插值并获得global_secondary_index: should be a list错误
• just usi纳克的VAR global_secondary_index = ["${var.global_secondary_index}"]得到global_secondary_index.0: expected object, got string错误
• 条件，但显然不支持列表或地图
• 合并地图global_secondary_index = ["${merge(var.global_secondary_index,map())}"]也得到global_secondary_index.0: expected object, got string错误

出如何使这项工作现在

Answer 1

思路似乎是一个缺少的功能：

https://github.com/hashicorp/terraform/issues/3388

就这一主题个

变化（合格的地图列表中的资源）：

https://github.com/hashicorp/terraform/issues/12294 https://github.com/hashicorp/terraform/issues/7705

最后一件事要注意，虽然，在条件语句就可以得到偷偷摸摸的那些。

resource "some_tf_resource" "meh" { 
    count = "${length(keys(var.my_map)) > 0 ? 1 : 0}" 
    # other resource settings here 
} 

使用count并将其设置为0是在早期版本中避开terraforms缺少条件的黑客方式。它仍然有效=）

尽管如果有其他资源依赖于meh资源，它会很快变得难看，所以如果您可以避免它，我不会太频繁地使用它。