When should Terraform configuration files be written when running terraform import on existing infrastructure?

Terraform configuration files should be written before executing the terraform import command because the import process requires a pre-existing configuration that describes the resource you want to manage. When you run terraform import, Terraform takes the existing infrastructure and associates it with the resource defined in your configuration. This means you need to have your configuration files ready to specify how the imported resource should be represented in Terraform's state.

By writing the configuration files beforehand, you ensure that Terraform can accurately link the existing resource in your cloud environment with the corresponding resource in your Terraform state. This association is crucial for Terraform to manage the resource going forward, as it relies on the definitions in the configuration files to understand how to interact with the existing infrastructure.

If the configuration files were written after the import or during the process itself, Terraform would not have the necessary context to map the existing state to the planned resource, leading to potential mismanagement or conflicts with the infrastructure. Thus, having the configuration files complete before import is fundamental for a smooth and effective integration of existing resources into Terraform's tracking and management.