Terraform 0.1 Variables

> 输入参数/输出结果/本地变量

# Input Variables
## 类型
```
#string,number,bool
#list(<TYPE>)
#set(<TYPE>)
#map(<TYPE>)
#object({<ATTR NAME> = <TYPE>, ... })
#tuple([<TYPE>, ...])

#官方例子
variable "image_id" {
  type = string
  description = "xxxxx" #可选
  sensitive = true #可选 plan/apply 的时候不显示出来
  nullable = false #可选 不允许为空
  
  validation { #检查input 是否符合条件
    condition     = length(var.image_id) > 4 && substr(var.image_id, 0, 4) == "ami-"
    error_message = "The image_id value must be a valid AMI id, starting with \"ami-\"."
  }
}

variable "availability_zone_names" {
  type    = list(string)
  default = ["us-west-1a"]
}

variable "docker_ports" {
  type = list(object({
    internal = number
    external = number
    protocol = string
  }))
  default = [
    {
      internal = 8300
      external = 8300
      protocol = "tcp"
    }
  ]
}
```
##使用方式
###命令行参数
```
terraform apply -var="image_id=ami-abc123"
terraform apply -var='image_id_list=["ami-abc123","ami-def456"]' -var="instance_type=t2.micro"
terraform apply -var='image_id_map={"us-east-1":"ami-abc123","us-east-2":"ami-def456"}'
```
###文件
写在.tfvars 后缀的文件中
```
cat testing.tfvars
image_id = "ami-abc123"
availability_zone_names = [
  "us-east-1a",
  "us-west-1c",
]

terraform apply -var-file="testing.tfvars"
```
###环境变量
设置TF_VAR_ 前缀的环境变量
```
export TF_VAR_image_id=ami-abc123
export TF_VAR_availability_zone_names='["us-west-1b","us-west-1d"]'
terraform plan
```
###var 生效顺序（后面的覆盖前面的）
```
1. 环境变量
2. terraform.tfvars 文件
3. *.auto.tfvars / *.auto.tfvars.json 文件
4. -var -var-file 设置的
```
# Output Variables
可以用于子模块返回变量给父模块
```
output "instance_ip_addr" {
  value = aws_instance.server.private_ip
  description = "xxx"
  sensitive   = true
}
```
# Local Variables
只能在同一个模块内使用
```
locals {
  service_name = "forum"
  owner        = "Community Team"
}
locals {
  # Common tags to be assigned to all resources
  common_tags = {
    Service = local.service_name
    Owner   = local.owner
  }
}
resource "aws_instance" "example" {
  # ...

tags = local.common_tags
}
```

乱读天书， 不求甚解

乱读天书，不求甚解