Variables and Outputs

Variable Types

Input Variables

• var.<“name”>

variable "instance_type" {
    description = "ec2 instance type"
    default     = "t2/micro"
}

Setting Input Variables

(In order of precedence, lowest -> highest)

• Manual entry during plan/apply.
• Default value in declaration block.
• TF_VAR_<“name”> environment variables.
• terraform.tfvars file.
• *.auto.tfvars file.
• Command line -var or -var-file.

Local Variables

• local.<“name”>

locals {
    service_name = "My Service"
    owner        = "Justin"
}

Output Variables

output "instance_ip_addr" {
    value = aws_instance.instance.public_ip
}

Types & Validation

Primitive Types:

• string
• number
• bool

Complex Types:

• list(<“TYPE”>)
• set(<“TYPE”>)
• map(<“TYPE”>)
• object({<“ATTR NAME”> = <“TYPE”>, …})
• tuple([<“TYPE”>,…])

Validation:

• Type checking happens automatically.
• Custom conditions can also be enforced.

Sensitive Data

Mark variables as sensitive:

• Sensitive = true. Pass to terraform apply with:
• TV_VAR_variable.
• -var (retrieved from secret manager).

Can also use external secret store:

• AWS Secrets Manager.