I strongly disagree with the link you’ve provided saying that queue bases systems are hard to measure the health of. I think the queue size is a good way to monitor the health of things, assuming you have some not super pathological workload. If your queues have a bounded size then alerting at various points towards that upper bound makes perfect sense
I’ve found alerting on queue length to be a path to false alarms, what most people care about is queue latency. How long does a message sit in the queue before being processed?
For some jobs the upper bound for that can be measured in days, for others it’s milliseconds, either way no one on the business side cares whether you have zero or a million jobs on the queue so long as they leave the queue quickly enough.
