How to fix There is no function named defaults in Terraform

Find all variable definitions that use optional() type constraints:

grep -r "optional(" .

This will show you where optional attributes are declared. The defaults() function was typically used to provide default values for these optional fields.

Instead of using defaults() in a locals block, specify defaults directly in the variable type definition:

Before (Terraform < 1.3):

variable "settings" {
  type = object({
    name    = string
    enabled = optional(bool)
  })
}

locals {
  settings = defaults(var.settings, {
    enabled = true
  })
}

After (Terraform >= 1.3):

variable "settings" {
  type = object({
    name    = string
    enabled = optional(bool, true)  # Default value here
  })
  default = null
}

Now the default value is specified inline with the optional attribute.

Delete any locals blocks that use the defaults() function entirely, since the defaults are now in the variable definition:

Remove this:

locals {
  # Delete this entire block - no longer needed!
  irsa_config = defaults(var.irsa_config, {
    create_kubernetes_namespace = true
    namespace_name             = "karpenter"
  })
}

The defaults are now applied automatically when the variable is declared with inline defaults.

If using third-party modules that still have defaults() calls, you have two options:

Option 1: Update the module to a newer version

module "eks_blueprints" {
  source = "aws-ia/eks-blueprints/aws"
  version = ">= 5.0"  # Use latest version without defaults()
}

Option 2: Fork and fix the module yourself
- Download the module source
- Update all defaults() calls to inline defaults
- Point your module source to your fork
- Submit upstream PR to help others

Verify your changes are syntactically correct:

terraform validate

This will catch any remaining issues with the function calls or syntax. If you get other errors, review the variable definitions for consistency.

Once validation passes, test your configuration:

# Reinitialize if module versions changed
terraform init -upgrade

# Plan the changes
terraform plan

# Apply if plan looks correct
terraform apply

The configuration should now work with Terraform 1.3.0+.