isaacs/cluster-master — pull request #14 by eirikurn (2013-07-18 00:58:45+00:00)
Title: Override cluster size with environment variable.

It's such a common requirement for ops to have the final say over the clustering, that configurability should be built in IMHO. Just like CLUSTER_MASTER_REPL.

Size is the most important setting for us, but the same argument might be used for other settings.