Aws_autoscaling_attachment alb_target_group_arn deprecation cannot modify, requires replace

Terraform Providers AWS
1

I’m doing some cleanup of deprecation warnings, and got something of a surprise. AWS provider is 4.62 and Terraform is 1.3.7

The deprecation warning (not a surprise) is:

Warning: Argument is deprecated
 
   with aws_autoscaling_attachment.app-waf-target-attach,
   on app_waf.tf line 182, in resource "aws_autoscaling_attachment" "app-waf-target-attach":
  182:   alb_target_group_arn   = aws_lb_target_group.app-waf-targets.arn
 
 Use lb_target_group_arn instead
 
 (and 8 more similar warnings elsewhere)

and the doc agrees:

alb_target_group_arn - (Optional, Deprecated use lb_target_group_arn instead) ARN of an ALB Target Group.

But in the past correcting deprecations that are just resource argument renames resulted in resource modifications or no change. This one, for some reason, wants to recreate the entire attachment resource. When I do a terraform plan against the suggested fix, I see this complete replace:

  # aws_autoscaling_attachment.app-waf-target-attach must be replaced
-/+ resource "aws_autoscaling_attachment" "app-waf-target-attach" {
      - alb_target_group_arn   = "arn:aws:elasticloadbalancing:us-west-2:REDACTED:targetgroup/app-waf-targets/605af3ca539faf1b" -> null # forces replacement
      ~ id                     = "app-wafs20210603160431333500000001-20210706185820536300000001" -> (known after apply)
      + lb_target_group_arn    = "arn:aws:elasticloadbalancing:us-west-2:REDACTED:targetgroup/app-waf-targets/605af3ca539faf1b" # forces replacement
        # (1 unchanged attribute hidden)
    }

Plan: 1 to add, 0 to change, 1 to destroy.

Is that expected behaviour for this change and safe to proceed? It appears in enough places that I’d really like to be sure.

2

Worked out fine, not a problem

3

Actually i think it is take downtime, without downtime can we do any other methods