Launch Template in AutoScaling group is not updated on change

[vikas027]

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Terraform CLI and Terraform AWS Provider Version

I don't think the terraform version matters here, I have tried with both terraform versions 1.1.2 and 0.13.6.
As per my testing, the problem lies with terraform provider version. v3.38 works fine while 3.69.0 and 3.70.0 definitely has issues. I am not sure in which version the bug was introduced.

Affected Resource(s)

• aws_autoscaling_group
• aws_launch_template

Terraform Configuration Files

Please include all Terraform configurations required to reproduce the bug. Bug reports without a functional reproduction may be closed without investigation.

# Launch Template
resource "aws_launch_template" "this" {
  …
}

# AutoScaling Group
resource "aws_autoscaling_group" "this" {
  depends_on = [aws_launch_template.this]

  launch_template {
    id      = aws_launch_template.this.id
    version = aws_launch_template.this.latest_version
  }
  …
  instance_refresh {
    strategy = "Rolling"
    preferences {
      min_healthy_percentage = 50
    }
  }
}

Expected Behavior

When there is a change in the launch template, the version of the launch template should be bumped (say 1 to 2) and should update the launch template version mapped to the AutoScaling group too.

Actual Behavior

Somewhere between versions 3.38.0 and 3.69.0, a bug has been introduced which bumps up the version of the launch template but not one mapped to the AutoScaling Group.

Steps to Reproduce

See this example

• In the first run (terraform apply), the launch template was created with v1 and the autoscaling group was too created with launch template v1
• Now, when a change is made to user data (just an example) which forces a change in the launch template, in the next run (terraform apply) launch template version is bumped from v1 to v2 but it does not gets changed in the ASG.
  There is a mismatch of the launch template latest version and the version in the ASG.
• In the subsequent run, the launch template version in the ASG gets updated to v2 and the instance refresh kicks in.
• Note, if we make another change to the launch template without applying it first, we get below error. This is because, now the launch template is at v3 but the ASG is still at v1.

Error: Provider produced inconsistent final plan

When expanding the plan for aws_autoscaling_group.this to include
new values learned so far during apply, provider
"registry.terraform.io/hashicorp/aws" produced an invalid new value for
.launch_template[0].version: was cty.StringVal("2"), but now
cty.StringVal("3").

This is a bug in the provider, which should be reported in the provider's own
issue tracker.

References

• More options for starting an instance refresh in ASG #16849
• Support ASG Instance Refresh #13785

[ericrichtert]

Check the release notes for 3.71. I guess it will released the tomorrow

[ewbankkit]

@vikas027 Thanks for raising this issue.
It has already been noticed in #22015. I'm going to close this one as a duplicate so that we can concentrate discussion in the linked issue.
Please add any additional comments there.

[github-actions]

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