We have a web service, which services both sets of higher priority and lower priority URLs and HAProxy is used for routing these requests to the web service.
Using a separate backend for these higher priority URLs and reserving servers only for this backend would be an under utilization of the servers, as these requests are low in number and infrequent. Is there a way to assign these higher priority URLs a higher weight in the backend queue, so that I don't want them to be waiting for long in the backend queue along with other lower priority URLs?
Looks like HAProxy team has released v1.9 with "Server Queue Priority Control", which pretty much does what is asked in this question. Cheers!
Source: https://www.haproxy.com/blog/haproxy-1-9-has-arrived/