ALB has no CloudWatch alarm on UnHealthyHostCount

What it checks

ALB: a linked target group lacks an UnHealthyHostCount alarm with matching LoadBalancer and TargetGroup dimensions.

Where it applies

Terraform: aws_lb, aws_alb

CloudFormation: AWS::ElasticLoadBalancingV2::LoadBalancer

How to fix it

1. Add aws_cloudwatch_metric_alarm: namespace=AWS/ApplicationELB, metric_name=UnHealthyHostCount, dimensions={LoadBalancer, TargetGroup}, threshold=1, evaluation_periods=2.

Frameworks

• AWS Well-Architected OPS.8
• AWS Well-Architected REL.6

These mappings are advisory, not an attestation of compliance.

Vendor documentation

All rules