Introduction Terraform variable file errors occur when required variables are missing, tfvars files have syntax errors, or variable values conflict with validation rules. This prevents terraform plan from executing.
Symptoms - `terraform plan` returns: "No value for required variable" - Error: "Invalid value for input variable" - Error: "Unsupported argument" in tfvars file - Variable validation rule fails - Sensitive variable exposed in logs
Common Causes - tfvars file not specified with -var-file flag - Typo in variable name in tfvars file - Missing required variable (no default value) - Variable type mismatch (string vs number vs list) - tfvars file contains syntax errors (missing quotes, commas)
Step-by-Step Fix 1. **Check which variables are required**: ```bash grep -E "variable |required|default" variables.tf ```
- 1.Run plan with explicit variable file:
- 2.```bash
- 3.terraform plan -var-file=prod.tfvars
- 4.# Or with individual variables
- 5.terraform plan -var="region=us-east-1" -var="environment=prod"
- 6.
` - 7.Validate tfvars file syntax:
- 8.```bash
- 9.# Check for common syntax errors
- 10.cat prod.tfvars
- 11.# Ensure all string values are quoted: region = "us-east-1"
- 12.# Ensure lists use proper syntax: zones = ["us-east-1a", "us-east-1b"]
- 13.
` - 14.Use variable validation to catch issues early:
- 15.```hcl
- 16.variable "environment" {
- 17.type = string
- 18.default = "dev"
- 19.validation {
- 20.condition = contains(["dev", "staging", "prod"], var.environment)
- 21.error_message = "Environment must be dev, staging, or prod."
- 22.}
- 23.}
- 24.
`