Is there a way to reuse a terraform script and make changes to it?

Question

I'm new to this terraform world and I've been assigned into the task of creating many configurations to azure with it.

I'm developing a main.tf script (which creates some resources, like resource group, vnets, kubernetes cluster, app services, etc.) and while coding it and executing Terraform apply, it seems to only apply what changed doing in fact updates.

Then we deleted the resource group the script created and a colegue of mine had to run the same script with terraform creating a resource group with another name since i didn't had a required permission, after that, if i run the command Terraform apply it fails and gives errors, that say that the resource cannot be created because it already exists.

After reading some documentation i found that it might be because of the state https://www.terraform.io/docs/state/index.html

Is the update of a script something that only works for each session of terraform?

Even doing a Terraform refresh doesn't seem to work. Or probably I'm just mistaking and there is no way to update some resources.

EDIT: for some reason the state file that was on the storage only had a few things, the solution was to delete everything and create again.

Answer 1

If someone else ran terraform apply for you because you didn't have access, and now you want to modify that terraform and run it yourself, you need to get the state file that was generated when that other person ran it. You absolutely have to maintain the Terraform state file somewhere, so that it can be accessed on subsequent runs. You should really configure a Terraform backend, instead of using local state files.

You need to be aware that Terraform stores everything it does in the state file, and refers to that file before every run. A terraform refresh only tells Terraform to refresh the state of the things that are in the state file, it doesn't rebuild the state file from scratch. Understanding Terraform state files is so fundamental to the use of Terraform that you really need to understand this before using it.