An application runs on EC2 instances behind an Application Load Balancer (ALB). The SysOps admin must create a custom health check for the instances. What is the most operationally simple way to implement this?

The most operationally simple way to implement a custom health check for EC2 instances behind an ALB is to configure the ALB health check with the correct Health Check Path. The ALB is designed to perform health checks directly on registered targets (your EC2 instances) by sending requests to a specified path and port. This built-in functionality requires minimal configuration and no additional services. Incorrect options: Writing state to S3 for the ALB to read is not a native ALB health check mechanism and would require complex custom logic and potentially introduce latency. Using Amazon ElastiCache to maintain instance health state would add unnecessary complexity and cost, as the ALB has native health check capabilities. Using API Gateway to run health checks is an indirect and overly complex approach for this scenario, as API Gateway is typically used for managing API access, not for direct instance health checks by an ALB.