// CellAZsByUnusednes sorts the availability zones in order of whether this cluster is using them or not
// An AZ that is not being used at all will be early in the result.
// All known AZs are included in the result
func (step AddNode) sortCellAZsByUnusedness(existingNodes []*structs.Node, cells cells.Cells) (vs *utils.ValSorter) {
azUsageData := map[string]int{}
for _, az := range cells.AllAvailabilityZones() {
azUsageData[az] = 0
}
for _, existingNode := range existingNodes {
if az, err := cells.AvailabilityZone(existingNode.CellGUID); err == nil {
azUsageData[az] += 1
}
}
vs = utils.NewValSorter(azUsageData)
vs.Sort()
return
}
