func (rc *replicationController) removePods(current types.PodLocations) error {
currentNodes := current.Nodes()
eligible, err := rc.eligibleNodes()
if err != nil {
return err
}
// If we need to downsize the number of nodes, prefer any in current that are not eligible anymore.
// TODO: evaluate changes to 'eligible' more frequently
preferred := types.NewNodeSet(currentNodes...).Difference(types.NewNodeSet(eligible...))
rest := types.NewNodeSet(currentNodes...).Difference(preferred)
toUnschedule := len(current) - rc.ReplicasDesired
rc.logger.NoFields().Infof("Need to unschedule %d nodes out of %s", toUnschedule, current)
for i := 0; i < toUnschedule; i++ {
unscheduleFrom, ok := preferred.PopAny()
if !ok {
var ok bool
unscheduleFrom, ok = rest.PopAny()
if !ok {
// This should be mathematically impossible unless replicasDesired was negative
return util.Errorf(
"Unable to unschedule enough nodes to meet replicas desired: %d replicas desired, %d current.",
rc.ReplicasDesired, len(current),
)
}
}
err := rc.unschedule(unscheduleFrom)
if err != nil {
return err
}
}
return nil
}
func (rc *replicationController) addPods(current types.PodLocations) error {
currentNodes := current.Nodes()
eligible, err := rc.eligibleNodes()
if err != nil {
return err
}
// TODO: With Docker or runc we would not be constrained to running only once per node.
// So it may be the case that we need to make the Scheduler interface smarter and use it here.
possible := types.NewNodeSet(eligible...).Difference(types.NewNodeSet(currentNodes...))
// Users want deterministic ordering of nodes being populated to a new
// RC. Move nodes in sorted order by hostname to achieve this
possibleSorted := possible.ListNodes()
toSchedule := rc.ReplicasDesired - len(currentNodes)
rc.logger.NoFields().Infof("Need to schedule %d nodes out of %s", toSchedule, possible)
for i := 0; i < toSchedule; i++ {
if len(possibleSorted) < i+1 {
errMsg := fmt.Sprintf(
"Not enough nodes to meet desire: %d replicas desired, %d currentNodes, %d eligible. Scheduled on %d nodes instead.",
rc.ReplicasDesired, len(currentNodes), len(eligible), i,
)
err := rc.alerter.Alert(rc.alertInfo(errMsg))
if err != nil {
rc.logger.WithError(err).Errorln("Unable to send alert")
}
return util.Errorf(errMsg)
}
scheduleOn := possibleSorted[i]
err := rc.schedule(scheduleOn)
if err != nil {
return err
}
}
return nil
}