[Bug]: ASG drainGroup calls SetInstanceProtection even when not protected

[bstriner]

Terraform Core Version

1.7.5

AWS Provider Version

1.7.5

Affected Resource(s)

aws_autoscaling_group

Expected Behavior

If an instance isn't protected, don't make extra API calls to remove protection

Actual Behavior

Deleting an ASG that doesn't have scale in protection can fail with "not authorized to perform: autoscaling:SetInstanceProtection". Role needs the ability to remove instance protection to be able to delete instances that aren't protected. Instance protection is made useless and role cannot be least privilege.

Relevant Error/Panic Output Snippet

Error: disabling Auto Scaling Group (X) scale-in protections: AccessDenied: User: arn:aws:sts::X:assumed-role/X/GHActionsSession is not authorized to perform: autoscaling:SetInstanceProtection on resource: arn:aws:autoscaling:us-east-1:X:autoScalingGroup:X because no identity-based policy allows the autoscaling:SetInstanceProtection action

Terraform Configuration Files

resource "aws_autoscaling_group" "asg" {
name = var.namespace
vpc_zone_identifier = local.subnets
desired_capacity = 1
max_size = 1
min_size = 1

launch_template {
id = aws_launch_template.ecs_lt.id
version = "$Latest"
}

tag {
key = "AmazonECSManaged"
value = true
propagate_at_launch = true
}
}

Steps to Reproduce

Any ECS/EC2 setup if your role doesn't have SetInstanceProtection, or use an admin role and see unnecessary SetInstanceProtection calls in cloudtrail.

Debug Output

No response

Panic Output

No response

Important Factoids

No response

References

In this previous merged PR, there is a loop checking ProtectedFromScaleIn: #23187
https://github.com/hashicorp/terraform-provider-aws/pull/23187/files

var instanceIds []string
for _, instance := range g.Instances {
if aws.BoolValue(instance.ProtectedFromScaleIn) {
instanceIds = append(instanceIds, aws.StringValue(instance.InstanceId))
}
}

That code code moved around, the current implementation in drainGroup loops through all instances with no filter.

terraform-provider-aws/internal/service/autoscaling/group.go

Line 1854 in e705bad

const batchSize = 50 // API limit.

Would you like to implement a fix?

Yes

[github-actions]

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Warning

This issue has been closed, meaning that any additional comments are hard for our team to see. Please assume that the maintainers will not see them.

Ongoing conversations amongst community members are welcome, however, the issue will be locked after 30 days. Moving conversations to another venue, such as the AWS Provider forum, is recommended. If you have additional concerns, please open a new issue, referencing this one where needed.

[github-actions]

This functionality has been released in v5.43.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

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