​​TF 1.1.0 was released, and maybe the most interesting feature is the ability to force vars to be not-null

 Non-nullable with a default: if left unset, or set explicitly to null, then
# it takes on the default value
# In this case, the module author can safely assume var.d will never be null
variable "e" {
  nullable = false
  default  = "hello"
}

# Non-nullable with no default: variable must be set, and cannot be null.
# In this case, the module author can safely assume var.d will never be null
variable "d" {
  nullable = false
}

By default, all variables set implicitly to nullable = true.

#terraform