ECS Fargate Event Message: service X failed to describe target health on target-group Y with (error ELB API Unavailable)

Hello,

ECS events flags any events when it is facing any issue and this event shows it is not able to describe the health checks of the target and might seems to be unhealthy and below could be some possible reasons for the target group to be unhealthy.

1. Improper IAM permissions for the ecsServiceRole IAM role
2. Container instance security group Elastic Load Balancing load
3. Loadbalancer not configured for all Availability Zones Elastic Load
4. Balancing load balancer health check misconfigured
5. container port mapping with host port were incorrect
6. ALB health check interval time was very short. Due to that, ALB was giving up immediately, not waiting for docker container to up and running properly.

Below is a troubleshooting guide for health check failures for Amazon ECS tasks on Fargate and health check failure on alb for your reference: https://repost.aws/knowledge-center/ecs-fargate-health-check-failures https://aws.amazon.com/premiumsupport/knowledge-center/elb-fix-failing-health-checks-alb/)