Vault is great. But if I were to start learning Terraform now, I'd probably ditch it in favor of Pulumi.

Terraform was supposed to make writing DRY easy. It's often more reasonable to copy-paste parts of configuration than to try make it DRY. HashiCorp seems to have the approach of "if something can be hacked around, even in a very convoluted way, we can ignore any feature requests for that thing to be doable in a normal fashion".

Instead of fixing Terraform, Hashi is creating more and more products that likely will be increasingly unpleasant to use and won't get reasonable fixes, just as Terraform.

The way HashiCorp approaches creating an ecosystem, makes me want to stay away.