// removePods unschedules pods for all scheduled nodes not selected
// by ds.nodeSelector
func (ds *daemonSet) removePods() error {
podLocations, err := ds.CurrentPods()
if err != nil {
return util.Errorf("Error retrieving pod locations from daemon set: %v", err)
}
currentNodes := podLocations.Nodes()
eligible, err := ds.EligibleNodes()
if err != nil {
return util.Errorf("Error retrieving eligible nodes for daemon set: %v", err)
}
// Get the difference in nodes that we need to unschedule on and then sort them
// for deterministic ordering
toUnscheduleSorted := types.NewNodeSet(currentNodes...).Difference(types.NewNodeSet(eligible...)).ListNodes()
ds.logger.NoFields().Infof("Need to unschedule %d nodes", len(toUnscheduleSorted))
ds.cancelReplication()
for _, node := range toUnscheduleSorted {
err := ds.unschedule(node)
if err != nil {
return util.Errorf("Error unscheduling node: %v", err)
}
}
ds.logger.Infof("Need to schedule %v nodes", len(currentNodes))
if len(currentNodes)-len(toUnscheduleSorted) > 0 {
return ds.PublishToReplication()
}
return nil
}
// addPods schedules pods for all unscheduled nodes selected by ds.nodeSelector
func (ds *daemonSet) addPods() error {
podLocations, err := ds.CurrentPods()
if err != nil {
return util.Errorf("Error retrieving pod locations from daemon set: %v", err)
}
currentNodes := podLocations.Nodes()
eligible, err := ds.EligibleNodes()
if err != nil {
return util.Errorf("Error retrieving eligible nodes for daemon set: %v", err)
}
// TODO: Grab a lock here for the pod_id before adding something to check
// contention and then disable
// Get the difference in nodes that we need to schedule on and then sort them
// for deterministic ordering
toScheduleSorted := types.NewNodeSet(eligible...).Difference(types.NewNodeSet(currentNodes...)).ListNodes()
ds.logger.NoFields().Infof("Need to label %d nodes", len(toScheduleSorted))
for _, node := range toScheduleSorted {
err := ds.labelPod(node)
if err != nil {
return util.Errorf("Error labeling node: %v", err)
}
}
ds.logger.Infof("Need to schedule %v nodes", len(currentNodes))
if len(currentNodes) > 0 {
return ds.PublishToReplication()
}
return nil
}
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
}
// Returns nodes to be removed and nodes to be added
func makeNodeChanges(oldNodeLabels []labels.Labeled, newNodeLabels []labels.Labeled) ([]types.NodeName, []types.NodeName) {
var oldNodeNames []types.NodeName
var newNodeNames []types.NodeName
for _, node := range oldNodeLabels {
oldNodeNames = append(oldNodeNames, types.NodeName(node.ID))
}
for _, node := range newNodeLabels {
newNodeNames = append(newNodeNames, types.NodeName(node.ID))
}
toRemove := types.NewNodeSet(oldNodeNames...).Difference(types.NewNodeSet(newNodeNames...)).ListNodes()
toAdd := types.NewNodeSet(newNodeNames...).Difference(types.NewNodeSet(oldNodeNames...)).ListNodes()
return toRemove, toAdd
}
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
}
// clearPods unschedules pods for all the nodes that have been scheduled by
// this daemon set by using CurrentPods()
// This should only be used when a daemon set is deleted
func (ds *daemonSet) clearPods() error {
podLocations, err := ds.CurrentPods()
if err != nil {
return util.Errorf("Error retrieving pod locations from daemon set: %v", err)
}
currentNodes := podLocations.Nodes()
// Get the difference in nodes that we need to unschedule on and then sort them
// for deterministic ordering
toUnscheduleSorted := types.NewNodeSet(currentNodes...).ListNodes()
ds.logger.NoFields().Infof("Need to unschedule %d nodes", len(toUnscheduleSorted))
ds.cancelReplication()
for _, node := range toUnscheduleSorted {
err := ds.unschedule(node)
if err != nil {
return util.Errorf("Error unscheduling node: %v", err)
}
}
return nil
}
// Naive implementation of a guard, this checks if any of the scheduled nodes
// are used by two daemon sets, does not pre-emptively catch overlaps by selector
// because of how kubernetes selectors work
//
// Also naively checks the selectors to see if there are any selector overlap
// if two label selectors are labels.Everything()
//
// Returns [ daemon set contended, contention exists, error ]
func (dsf *Farm) dsContends(dsFields *ds_fields.DaemonSet) (ds_fields.ID, bool, error) {
// This daemon set does not contend if it is disabled
if dsFields.Disabled {
return "", false, nil
}
// Get all eligible nodes for this daemon set by looking at the labes.NODE tree
eligibleNodes, err := dsf.scheduler.EligibleNodes(dsFields.Manifest, dsFields.NodeSelector)
if err != nil {
return "", false, util.Errorf("Error retrieving eligible nodes for daemon set: %v", err)
}
// If this daemon set has a node selector set to Everything, check the labels
// of other daemon sets
for _, child := range dsf.children {
everythingSelector := klabels.Everything().String()
if !child.ds.IsDisabled() && child.ds.PodID() == dsFields.PodID && child.ds.ID() != dsFields.ID {
// Naively check if both selectors are the Everything selector plus
// something else or if both selectors are the same
//
// This will still think that the following two selectors contend:
// { az = zone_one, az != zone_one } and {} (the everything selector)
// even though the first selector doesn't select anything
//
// If either the child or the current daemon set has the everything selector
// then they contend
if dsFields.NodeSelector.String() == everythingSelector ||
child.ds.GetNodeSelector().String() == everythingSelector {
dsf.raiseContentionAlert(child.ds, *dsFields)
return child.ds.ID(), true, nil
}
// If both daemon sets have the same selector, then they contend
//
// This will still think that the following two selectors contend:
// { az = zone_one, az != zone_one } and { az = zone_one, az != zone_one }
// even though they don't select anything
if dsFields.NodeSelector.String() == child.ds.GetNodeSelector().String() {
dsf.raiseContentionAlert(child.ds, *dsFields)
return child.ds.ID(), true, nil
}
// Check the child's eligibleNodes, then intersect it to see if there
// are any overlaps
//
// NOTE: This is naive, it does not account for new nodes, so any alerts
// we get will be caused by adding new nodes by both human, machine error,
// are starting up a daemon set farm where contention already exists
scheduledNodes, err := child.ds.EligibleNodes()
if err != nil {
return "", false, util.Errorf("Error getting scheduled nodes: %v", err)
}
intersectedNodes := types.NewNodeSet(eligibleNodes...).Intersection(types.NewNodeSet(scheduledNodes...))
if intersectedNodes.Len() > 0 {
dsf.raiseContentionAlert(child.ds, *dsFields)
return child.ds.ID(), true, nil
}
}
}
return "", false, nil
}