An HCP Terraform workspace variable allowed_cidrs holds ["10.0.0.0/16", "10.1.0.0/16"]. The configuration declares the variable as list(string), but runs fail because the value arrives as a single string. How should the workspace variable be fixed?
Select an answer to reveal the explanation.
![To Create an exciting colorful infographic that explains the concepts in the question: Question: An HCP Terraform workspace variable allowedcidrs holds ["10.0.0.0/16", "10.1.0.0/16"]. The configuration declares the variable as list(string), but runs fail because the value arrives as a single string. How should the workspace variable be fixed? Correct Answer: Enable the variable's HCL option so HCP Terraform reads the value as an HCL list, not a string Put EVERY visible label in double quotes. No people. No A/B/C/D letters. In one of the four corners put a little "Navy Duck".](/media/hashicorp/terraform-pro-002/TERRAFORM-PRO-002-e1-q172.webp)
Short Explanation
HCP Terraform treats every variable value as text unless you tell it otherwise. Tick the HCL checkbox on that Terraform variable and the brackets become a real list, written in the same syntax you'd put in a .tf file. Sensitive, jsonencode or a variable set won't change how the text is read.
Full Explanation
Terraform variables defined in an HCP Terraform workspace are strings by default. To supply a list, map or other complex value, the variable's HCL option is enabled and the value is entered in normal HCL syntax; the workspace's Terraform version interprets it, so ["10.0.0.0/16", "10.1.0.0/16"] then arrives as a list that satisfies list(string). The HCL option is available for Terraform variables, not environment variables. Marking a variable sensitive only makes it write-only in the UI and hides it in logs; the value is still treated as a string. Wrapping the value in jsonencode() without the HCL option simply stores that text as a literal string, and jsonencode would produce a string in any case, not a list. Variable sets follow the same rules as workspace variables: a set's Terraform variable is also a string unless its HCL option is enabled, and priority affects precedence, not type. Exam caveat: once the HCL option is on, the value must be valid HCL; a missing quote or bracket fails the run. Operational check: edit the variable, enable HCL, save, queue a plan, and confirm the resources receive two CIDR entries rather than a type error.