Terraform - Delete all resources except one

Question

I have a Terraform 0.11 project with 30-40 different resources. I would like to delete all of them except a few - and those few are logically related to each other.

I was looking for something close to terraform destroy --except=resource-id but that of course doesn't exist.

Is there a way to achieve that without too much scripting (Terraform admins have various OSs)? Would using modules make that process easier perhaps?

Answer 1

There is no exist feature in terraform destroy command currently. If you really want to do that, and you know what you do, here is the workaround.

# list all resources
terraform state list

# remove that resource you don't want to destroy
# you can add more to be excluded if required
terraform state rm <resource_to_be_deleted> 

# destroy the whole stack except above excluded resource(s)
terraform destroy 

So why do these commands work for your idea?

The state (*.tfstate) is used by Terraform to map real world resources to your configuration, keep track of metadata.

terraform state rm cleans an record (resource) from the state file (*.tfstate) only. It doesn't destroy the real resource.

Since you don't run terraform apply or terraform refresh, after terraform state rm, terraform doesn't know the excluded resource was created at all.

When you run terraform destroy, it has no detail about that excluded resource’s state and will not destroy it. It will destroy the rest.

By the way, later you still have chance to input the resource back with terraform import command if you want.