I managed to achieve load balancing for a fleet of microservices using vulcand [0] and marathon callbacks [1].

It listens for marathon callbacks (for app create/update/scale), or when a task is killed/lost and updates the backends in etcd, propagating to all vulcand load balancers.

The tool is available on github [2]

[0] https://vulcand.io/proxy.html#backends-and-servers

[1] https://mesosphere.github.io/marathon/docs/event-bus.html

[2] https://github.com/kuende/kameni