Terraform - Delete all resources except one

I have a bit of a different work around. The resources I do not want to delete with "terraform destroy" I create as "null_resource" using a provisioner with CLI. You can still use your variables in terraform as well.

for example (Create a resource group, but it is persistent due to null_resource)

resource "null_resource" "backend-config" {
        provisioner "local-exec" {
        command     = <<EOT
    az group create --location ${var.Location} --name ${var.Resource_group_name} --tags 'LineOfBusiness=${var.Lob}' 'Region=${var.Region}' 'Purpose="Terraform-Primary-Resource-Group-${var.Lob}'
    EOT
        interpreter = ["Powershell", "-Command"]
      }
    }

Now if you destroy the resources using terraform destroy. Any null_resource will remain intact.

Targetting each resource (while skipping over the data resources) except the one you want is probably the only way atm:

#! /bin/bash

while read -r resource; do
    terraform destroy -target="$resource"
done < <(terraform state list | grep -vE "^data\." | grep -vE "dont_remove|also_important")

There is no --except feature in terraform destroy command currently. If you really want to do that, and you know what you are doing, 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 a 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 import the resource back with terraform import command if you want.