I would like to be able to add a node to a running cluster.
For example if I have created a hadoop, hbase, zookeeper cluster I would like to be able to add region servers to hbase, Zookeeper nodes to the quorum, and task nodes to hadoop.
Something akin to the functionality of the hbase-ec2 script. Where if I launch a node on an already running cluster. It is configured to join the cluster.
We should also provide hooks for removing nodes from the cluster. In many situations removing nodes is much harder that adding them, however this issue should mostly care with cloud mgmt and providing the hooks for addition/deletion separate issues should handle the add/remove process for each service, so it won't be a gargantuous task.