Azure Application Gateway CPU Utilization Metric
The Application Gateway offering provides quite a few useful metrics, but lacks some core performance metrics. Please, at a minimum, provide a metric and alert for CPU utilization of the instances behind an Application Gateway. When CPU utilization is not monitored at this level, it can affect the performance of dependent applications.
Siebert Adrien commented
Agreed; there are presently no metrics available to indicate when traffic to an Application Gateway is exceeding its capacity.
This is also relevant for version 2 of the product, where autoscaling is capped to a "maximum instance count", and thus can still reach capacity.
Note that Azure Support can provide CPU summaries, in case anyone encounters issues.