Hi everyone! I'm new here but have been exploring discussions for a while. I'm facing an issue with Azure Front Door (AFD) and would love some advice. We have a group with 7 Azure App Service origins in East US 2, all set with priority 1 and weight 1000. I'm trying to achieve a more balanced request distribution among these origins. It seems like AFD always favors the last origin in the list, cycling through them in reverse order (from 7 to 1), rather than utilizing them equally. This is evident from our health check results, and we're noticing that origin 7 is experiencing high CPU usage and request counts compared to the others, while origins 1-5 are underutilized. I'm aware that AFD has configured latency and health checks in place, which all origins consistently meet. We've looked into alternatives like Cloudflare, which offers a randomized backend selection mechanism. Has anyone found a way to make AFD distribute requests more evenly when all origins are healthy? Any help or insight would be appreciated!
3 Answers
Have you checked if session affinity is enabled? Sometimes that can skew how requests are distributed among the origins. If it’s on, it might be forcing some requests to stick to certain origins instead of spreading them out evenly.
It might help to rethink the health check settings slightly. You could try adjusting the probe settings to see how that affects the selection. Sometimes tweaking the intervals and sample sizes can yield better results by improving how quickly AFD can react to origin performance variances during low loads.
I understand your frustration. AFD doesn’t currently support a true random selection for origins based on health checks. Many users have experienced similar issues and generally end up implementing additional balancing layers outside of AFD to achieve this feature. Have you considered using Azure Traffic Manager in conjunction with AFD for better distribution?
I actually turned off session affinity for both AFD and all app services since our app is stateless. I thought that would help with balancing. I also have health probes active to monitor performance. Thanks for the tip though!