Azure DevOps - Azure library variables to TF variables

[space3]

I want to map Azure Library variables to TF variables. I am unable to do so, output.tf doesn't display the variables when I try to pass them through the pipeline. Anyone has done this? Thanks RK.

eg: 

TF_VAR_x = $x

TF_VAR_y = $y

output.tf

output "X"{

value = X

}

[#2]

Unfortunately below assignment didn't work for me. Did anyone try?

https://www.terraform.io/docs/commands/environment-variables.html

https://stackoverflow.com/questions/54247055/how-to-reference-a-variable-in-terraform-file-for-azure...