Right now it's clumsy if the user wants to have a routing rule that matches and then sends traffic to a number of upstream clusters on a % basis. We should support this directly both via static percentages as well as runtime override of the percentages.

The rule might look something like:

{
...
"weighted_clusters:" [
  { "name": "cluster1", "weight": 33 },
  { "name": "cluster2", "weight": 33 },
  { "name": "cluster3", "weight": 33 },
]
}

Need to also specify what the rule would look like with runtime overrides. Open so to suggestions here.

cc @rshriram