Hey one thing I realize while looking it this. I'm not sure it says anywhere in any docs that you are supposed to set the master to `yarn-standalone` when initializing a SparkContext for use on yarn. I realize this is unrelated to your PR, but it would be great if you could add that to the YARN documentation /cc @tgraves (maybe I missed it?). Also it's a little confusing calling it `yarn-standalone` - it might make sense to rename this to `yarn-cluster` and `yarn-client` since there is a name collision with "The standalone cluster manager".