I have an ELB (Network Load Balancer with a couple of Auto Scaling Groups as Target Group) that has periodical health check fails (i.e. some instances would be marked as unhealthy and then recover after a few minutes). The health check is a simple static page (i.e. /health_check).
The timing seems to be at the same time when the host is having heavy network load (downloading large files from S3), but I want to have more information (e.g. they are failing the active health check or passive health check as mentioned in https://docs.aws.amazon.com/elasticloadbalancing/latest/network/target-group-health-checks.html).
However, I am not able to find the health check history or logs from ELB. All my search finds is about the Access Log for ELB (https://docs.aws.amazon.com/elasticloadbalancing/latest/network/load-balancer-access-logs.html) which is about the actual user requests.
Is this health check history / log accessible anywhere?
