devops-directive-terraform-course/04-variables-and-outputs/examples

Variables

Variable block

must define variable block

variable "var_name" {
  type = string
}

Variable types

• string
• number
• bool
• list()
• set()
• map()
• object({ = , ... })
• tuple([, ...])

Variable files

variables.tfvars (or <FILENAME>.auto.tfvars) automatically applied

Apply default

terraform apply

Apply a different variable file

terraform apply -var-file=another-variable-file.tfvars

Passing Variable via Prompt

If value not specified, Terraform will prompt for value. (this is okay for testing... but don't depend on it since you should be automating things!)

  var.db_pass
  password for database

  Enter a value:

Passing Variables via CLI

terraform apply -var="db_pass=$DB_PASS_ENV_VAR"

Local Variables

Allows you to store the value of expression for reuse but doesn't allow for passing in values

locals {
  extra_tag = "extra-tag"
}

Output Variables

Allows you to output some value (which might not be known ahead of time).

For example it might be useful to know the IP address of a VM that was created:

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

Sample output:

db_instance_addr = "terraform-20210504182745335900000001.cr2ub9wmsmpg.us-east-1.rds.amazonaws.com"
instance_ip_addr = "172.31.24.95"

Will be output after terraform apply or terraform output