This issue was originally opened by @Juberstine as hashicorp/terraform#15944. It was migrated here as a result of the provider split. The original body of the issue is below.

I needed to remove the key_name attached to an instance created by an ASG via a LC.

But running plan showed no change to be made.

Terraform Version

v0.9.5

Affected Resource(s)

Please list the resources as a list, for example:

aws_launch_configuration
Terraform Configuration Files

Actual code block post update. The only change made here was the removal of key_name:

resource "aws_launch_configuration" "triton-as-conf" {
  name_prefix   = "triton-${var.name}-launch-conf"
  image_id      = "${var.container_host_ami}"
  instance_type = "${var.container_host_instance_type}"

  security_groups = [
    "${aws_security_group.ssh.id}",
    "${aws_security_group.web.id}",
    "${aws_security_group.self_reference.id}",
  ]

  user_data            = "${data.template_file.user_data.rendered}"
  iam_instance_profile = "${aws_iam_instance_profile.container_host.name}"

  lifecycle {
    create_before_destroy = true
  }
}

All vars are set.

Inside the launch configs, the only code change was the removal of:

key_name = "${aws_key_pair.deployer.key_name}"

The above var was set but the concept here is that removing key_name does not trigger the LC to change.

Expected Behavior

LC should have been recreated without key_name.

Actual Behavior

Nothing.

Steps to Reproduce

Please list the steps required to reproduce the issue, for example:

terraform apply
Remove the key_name value from launch configs
terraform plan
terraform apply

Seems similar to the issue another user experience with EBS:

hashicorp/terraform#14826