CODEWITHSUNDEEP
terraformterraform-provider-aws
kumar
kumar

Reputation: 9387

In Terraform, how can I define a list of objects?

In Terraform, how do we define a list of objects?

variables.tf

variable "aws_cluster_arn" {
  type = string
  
}

variable "aws_ecs_placement_strategy" {
  type = list(object)
}

in configuration.tfvars

aws_ecs_placement_strategy=(object({type="spread",field="attribute:ecs.availability-zone"}),object({type="BinPack",field="CPU"}))

I am getting following error:

Error: Invalid type specification

on variables.tf line 53, in variable "aws_ecs_placement_strategy":
53: type = list(object)

Upvotes: 2

Views: 3268

Answers (2)

dingo
dingo

Reputation: 906

One often wants to be able to define a list of custom objects as variables in Terraform, and it's more straightforward than you'd think.

It can simply be defined as follows:

variable "var_name" {
   val_a = string
   val_list = list(object({
      list_val_1 = string
      list_val_2 = number
   }))
}

This way you can define a list of variable values that can be iterated through to generate resources dynamically. When paired with the 'dynamic' block, it becomes a a powerful tool. It can be used as follows, assuming we define a list of variables following the example above:

dynamic "resource_name" {
   for_each = var.var_name.val_list
   content = {
      val_1 = resource_name.value.list_val_1
      val_2 = resource_name.value.list_val_2
   }
}

Following this pattern can make your Terraform code much more modular and reusable, allowing for dynamic definitions that span multiple use cases.

Upvotes: 0

Adil B
Adil B

Reputation: 16778

When defining an object type, you should specify all of the object's fields and their types like so:

variable "aws_ecs_placement_strategy" {
  type = list(object({
     type = string,
     field = string
  }))
}

Upvotes: 5

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