Default Termination Policy must be last

[blairham]

When adding multiple termination policies to an autoscaling group and one of them is the 'Default', the 'Default' must be last in the list. Terraform currently does not respect that. Here is the sample code that would demonstrate this case:

variable "termination_policies" {
default = "OldestInstance,Default"
}

resource "aws_autoscaling_group" "blue" {
...
termination_policies = ["${split(",", var.termination_policies)}"]
...
}

[pforman]

This should be mostly addressed by #2890, which was merged for upcoming release in 0.6.7.

The reason you're seeing that behavior is that prior to #2890 the list was implemented as a hashed set, so the order was dependent on the hash values of the items.

I fixed that so well-defined cases (like yours) will work properly. Terraform doesn't currently allow for validating the contents of a list parameter, so if you provide something like

termination_policies = ["Default","OldestInstance"]

it will pass a terraform plan but fail on terraform apply (with a meaningful error message).

So AWS will enforce that "Default" must be last, but Terraform can't (yet). However, in 0.6.7 it should respect the order provided.

[blairham]

This looks great @pforman, thanks!

[ghost]

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