Description
An Auto Scaling group serving requests through a load balancer needs an association with that load balancer or its target group. Workloads such as queue workers may not need a load balancer; choose according to the service design.
Potential impact
If an association required by the service is missing, newly launched instances may not receive requests.
Remediation
Use load_balancers for a Classic ELB or target_group_arns for an ALB/NLB. To replace instances based on load-balancer health checks, also enable ELB health checks in Auto Scaling.
Examples
The revised example associates the group with an existing Classic ELB named elb-1. The launch template and load balancer are defined separately.
Before
hcl
resource "aws_autoscaling_group" "example" {
availability_zones = ["us-east-1a"]
desired_capacity = 1
max_size = 1
min_size = 1
launch_template {
id = aws_launch_template.foobar.id
version = "$Latest"
}
}
After
hcl
resource "aws_autoscaling_group" "example" {
availability_zones = ["us-east-1a"]
desired_capacity = 1
max_size = 1
min_size = 1
launch_template {
id = aws_launch_template.foobar.id
version = "$Latest"
}
load_balancers = ["elb-1"]
}