Preconditions and Postconditions
Input validation stops resource creation in the case of invalid inputs if you run the configuration script, which means the validation takes place before the terraform apply operation.
But if you want a similar condition(s) to be applied to resources, data sources, or outputs and the evaluation has to be done before and after, based on the scenario, Terraform has precondition and postcondition to explore.
For resources and data sources, the precondition and postcondition checks need to be added under the lifecycle {} block. The outputs can contain a precondition check only without the lifecycle {} block. The precondition and postcondition check will contain the condition and the error message parameters, such as the one you saw with the input validation.
Look at the following code snippet:
data "aws_ecr_repository" "repo_data" {
name = aws_ecr_repository.app_repo.name
lifecycle {
...
