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ELB Target Health

Elastic Load Balancing (v2) distributes traffic across multiple targets such as EC2 instances, IP addresses, and Lambda functions. The ELB Target Health resource in Overmind represents the status of a single target as returned by the AWS DescribeTargetHealth API. It shows whether the target is healthy, unhealthy, initialising, or draining, together with any failure reasons, so you can spot issues before a change is deployed. Official documentation: https://docs.aws.amazon.com/elasticloadbalancing/latest/APIReference/API_DescribeTargetHealth.html

Supported Methods​

  • GET: Get target health by unique ID ({TargetGroupArn}|{Id}|{AvailabilityZone}|{Port})
  • LIST
  • SEARCH: Search for target health by target group ARN

ec2-instance​

When the target group’s type is instance, each registered EC2 instance appears as an ELB target. The target-health record shows whether that particular EC2 instance is currently considered healthy by the load balancer.

lambda-function​

For target groups of type lambda, the Lambda function itself is the target. The target-health item reports the invocation health of the function as assessed by the load balancer.

ip​

If the target group is of type ip, every registered IP address becomes a target. The target-health entry records the health of that IP address, enabling you to see whether traffic will be routed to it.

elbv2-load-balancer​

The load balancer associated with the target group uses these health results to decide where to send traffic. Linking to the load balancer lets you trace how a target’s health status could affect overall load-balancer behaviour.