Avoid replacement in the terraform code while changing module versions-CodePudding

Well, I have some resources in AWS that were created via terraform module. But now I have to change source module to the identical module except some stuff like name of some resources and now I need to use another module and avoid replacement. Now I have problems only with names of 4 resources. Here is the example: KMS-ALIAS: BEFORE: kms-alias-s3bucket, CHANGES IN MODULE: kms-alias-s3bucket-dev. How to avoid replacement without changing the resources names'. I heard about terraform state mv but actually don't know how to properly configure that Here is the output: output of terraform plan

Here is how changes looks like:

before

after

CodePudding user response：

Changing the terraform state to add the prefix -dev in the resources names will force terraform to diff from your Cloud environment, any update on those resources afterwards will force a replacement unless you do not touch those resources anymore.

If you cloud environment has this bucket named xyz, you want your state with the bucket name as xyz. So changing those names will depend on what those 4 resources are, bucket name change forces replacement for instance, so if you really want this environment as prefix you can create another bucket with the desired name <bucket-name>-dev and move everything from the old to the new one and then import the new one using terraform import into your state, then terraform will not force replacement anymore.

terraform import aws_s3_bucket.bucket <new-bucket-name>-dev

Additional Info

Modifying your state directly is usually for changing structural stuff and the resource local name could be among those potential changes.

resource "aws_s3_bucket" "bucket" { #bucket = resource local name
  bucket = "my-tf-test-bucket" # my-tf-test-bucket = bucket name itself, it is unique and could not be changed without creating another bucket. AWS api does not allow that. That's why always depends on which resource.

  tags = {
    Name        = "My bucket"
    Environment = "Dev"
  }
}

In resume I would say if terraform try to replace when you change some argument (such as "bucket name") you will need to replace to be applied in your remote system (cloud environment). If AWS API / AWS Console allow you to change without recreating (even terraform saying that you need, it could happen sometimes), you can then import the resource into your state instead of editing the state.