Creating health probes
After the frontend and the backend of the load balancer are defined, traffic is evenly distributed among endpoints in the backend. But what if one of the endpoints is unavailable? In that case, some of the requests will fail until we detect the issue, or even fail indefinitely should the issue remain undetected. The load balancer would send a request to all the defined endpoints in the backend pool and the request would fail when directed to an unavailable server.
This is why we introduce the next two components in the load balancer—health probes and rules. These components are used to detect issues and define what to do when issues are detected.
Health probes constantly monitor all endpoints defined in the backend pool and detect if any of them become unavailable. They do this by sending a probe in the configured protocol and listening for a response. If an HTTP probe is configured, an HTTP 200 OK response is required to be considered successful...