Possible values:
  available - If a node is available, this means it is detected on the internal cluster network and can be added to the cluster. Nodes that have a membership of “available” are not returned when a GET request is called when the cluster exists. A query on the “membership” property for available must be provided to scan for nodes on the cluster network. Nodes that have a membership of “available” are returned automatically before a cluster is created.
  joining - Joining nodes are in the process of being added to the cluster. The node may be progressing through the steps to become a member or might have failed. The job to add the node or create the cluster provides details on the current progress of the node.
  member - Nodes that are members have successfully joined the cluster.