What is a target group, and how do health checks work on a load balancer?
AWS · Basic level
Answer
A target group is the backend pool for a load balancer. Health checks determine whether each target should receive traffic, so the health endpoint must reflect real readiness and dependencies, not just process liveness.
Technical explanation
A shallow health check can pass while real traffic fails, so readiness should reflect critical dependencies where appropriate.
Compute design should balance availability, scaling speed, startup time, instance limits, health checks, and deployment rollback, not just raw instance size.
Autoscaling and load balancing only work well when health checks reflect readiness and when applications externalize state.
Cost optimization should be tied to utilization data and workload tolerance for interruption, commitment, and architecture changes.
Hands-on example
1. Build a launch template or workload definition with IAM role, security groups, user data/bootstrap, health endpoint, and CloudWatch metrics.
2. Place compute behind an ALB/NLB or scaling group and run a controlled load test to observe scaling and health behavior.
3. Tune scaling policy, warmup/cooldown, target group health checks, and rollback procedure.
4. Compare cost and reliability after the test, then promote the configuration through IaC.
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