Configuring List Variables in HCP Terraform Cloud

Configuring List Variables in HCP Terraform Cloud

Issue

When setting list-type variables in HCP Terraform Cloud, you may encounter the following error:

Error: Invalid value for input variable
The given value is not suitable for var.subnet_appgw_address: list of string required.

Solution

1. Variable Definition in Terraform

The variable is correctly defined in variables.tf:

variable "subnet_appgw_address" {
  description = "Address prefixes for the application gateway subnet"
  type        = list(string)
  default     = ["10.148.36.0/24"]
}

2. Correct Configuration in HCP Terraform Cloud

To properly set list variables in HCP Terraform Cloud:

1. Navigate to your workspace variables
2. Add/Edit the variable subnet_appgw_address
3. Enter the value: ["10.148.36.0/24"]
4. Important: Check the “HCL” checkbox
5. Save the variable

Common Mistakes to Avoid

• Don’t use escaped quotes (\")
• Don’t wrap the entire value in additional quotes
• Don’t forget to check the “HCL” checkbox

Example

✅ Correct:

["10.148.36.0/24"]

❌ Incorrect:

"[\"10.148.36.0/24\"]"

Additional Notes

• This approach applies to all list-type variables in HCP Terraform Cloud
• The HCL checkbox tells HCP to parse the input as HCL syntax rather than a plain string
• Always validate the variable type matches your Terraform configuration