Variable Validation
VARCHK operation has been added to the execution engine to allow different validation rules and logging.
See Variable Validation Blog post for full story.
There are 5 rules available, two for plain text and three for secrets. When validating a secret against a known MD5 value, either a literal or variable can be supplied.
# Plain text values
OPT_ARG # Optional plain text
terraform_version=required # Required plain text
# Secret values
TERRAFORM_TOKEN=optional # Optional secret
TERRAFORM_TOKEN=secret # Required secret
TERRAFORM_TOKEN=$TERRAFORM_TOKEN_MASK # Required secret verified against supplied SHA-256 value