Sticky load balancer with application-managed cookie


I noticed that if you configure a load balancer stickiness with the create new cookie option you will get the cookie at the first request and by setting it on the next requests you will make them go to the same container behind the lb.

Is there a way to set the sticky cookie from an application that is using that lb, instead of using the one generated by Rancher? We would prefer to set it to a custom hash by the application.