References to Values

Terraform makes several kinds of named values available. Each of these names is an expression that references the associated value. You can use them as standalone expressions, or combine them with other expressions to compute new values. For a comprehensive list and details of all the expressions check here (opens in a new tab).

Data Sources

Use the data keyword and the format is as follows:

data.<data source type>.<instance label>.<instance attribute>

For example:

main.tf

data "akamai_group" "my_group" {
     group_name   = "My Group"
     contract_id  = "1-2AB34C"
}
 
resource "akamai_property" "example" {
    group_id    = data.akamai_group.my_group.id
    # ... other configuration ...
}

Resources

Referencing resources is similar to referencing data sources, except there is no data keyword. The format is as follows:

<resource type>.<instance label>.<instance attribute>

For example:

main.tf

resource "akamai_edge_hostname" "ehn" {
  product_id    = "prd_Fresca"
  contract_id   = data.akamai_contract.contract.id
  group_id      = data.akamai_group.group.id
  ip_behavior   = "IPV4"
  edge_hostname = "www.example.com.edgesuite.net"
}
 
resource "akamai_property" "property" {
  name        = "property"
  # ... other configuration ...
  hostnames {
    cname_from             = "www.example.com"
    cname_to               = akamai_edge_hostname.ehn.edge_hostname
    cert_provisioning_type = "CPS_MANAGED"
  }
}

Variables

The syntax is:

var.<variable name>

For example, using the variables below:

variables.tf

variable "contract_id" {
  type        = string
  description = "Contract ID"
}
variable "group_id" {
  type        = string
  description = "Group ID"
}
variable "property_name" {
  type        = string
  description = "Name for the property to be managed"
}

You could create an akamai_property resource like this:

main.tf

resource "akamai_property" "my_property" {
    name        = var.property_name
    product_id  = "Fresca"
    contract_id = var.contract_id
    group_id    = var.groupid
}

Locals

The syntax is:

local.<variable name>

Following the same exampe from above we can use locals instead of variables.

main.tf

locals {
  contract_id = "Contract ID"
  group_id = "Group ID"
  property_name = "Name for the property to be managed"
}
 
resource "akamai_property" "my_property" {
    name        = local.property_name
    product_id  = "Fresca"
    contract_id = local.contract_id
    group_id    = local.groupid
}

Child Module Outputs

We will review Terraform modules later on, however for now the syntax to create a reference from a module output is:

The syntax is:

module.<module name>.<output name>

For example, if you have a module that builds a property's rule tree and outputs the rule format the rules:

main.tf

module "rule_tree" {
  source          = "./modules/rules"
  origin_hostname = var.my_origin_hostname
  cp_code         = var.my_cp_code
}
 
resource "akamai_property" "my_property" {
  name        = var.property_name
  # ... other configuration ...
  rule_format   = module.rule_tree.rule_format
  rules         = module.rule_tree.rules
}

Expressions Conditionals