HAproxy path based routing of web containers

We are students working on a project using nomad haproxy and consul and we are new to all these technologies. We have VMs running on a server ( we used Vagrant) each Vm is hosting web containers and orchestred by nomad and we chose to install HAproxy on each Vm as a service. Now the problem is these containers will run on demand and Haproxy will be reloaded to take new configuration into consideration but in this case the configuration of the apache containers must be updated to take the path defined in HAproxy into consideration.
For example :
acl challenge1 path_beg -i /challenge1/
use_backend container1 if challenge1

in order for this to work i should add /challenge1/ directory to apache conf files.
If anyone have a solution to this problem please dont hesitate to share your opinion.