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228 lines
9.7 KiB
Go
228 lines
9.7 KiB
Go
/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package deployment
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import (
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"fmt"
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"sort"
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"github.com/golang/glog"
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"k8s.io/client-go/util/integer"
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extensions "k8s.io/kubernetes/pkg/apis/extensions/v1beta1"
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"k8s.io/kubernetes/pkg/controller"
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deploymentutil "k8s.io/kubernetes/pkg/controller/deployment/util"
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)
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// rolloutRolling implements the logic for rolling a new replica set.
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func (dc *DeploymentController) rolloutRolling(deployment *extensions.Deployment) error {
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newRS, oldRSs, err := dc.getAllReplicaSetsAndSyncRevision(deployment, true)
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if err != nil {
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return err
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}
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allRSs := append(oldRSs, newRS)
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// Scale up, if we can.
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scaledUp, err := dc.reconcileNewReplicaSet(allRSs, newRS, deployment)
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if err != nil {
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return err
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}
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if scaledUp {
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// Update DeploymentStatus
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return dc.syncRolloutStatus(allRSs, newRS, deployment)
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}
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// Scale down, if we can.
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scaledDown, err := dc.reconcileOldReplicaSets(allRSs, controller.FilterActiveReplicaSets(oldRSs), newRS, deployment)
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if err != nil {
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return err
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}
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if scaledDown {
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// Update DeploymentStatus
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return dc.syncRolloutStatus(allRSs, newRS, deployment)
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}
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// Sync deployment status
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return dc.syncRolloutStatus(allRSs, newRS, deployment)
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}
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func (dc *DeploymentController) reconcileNewReplicaSet(allRSs []*extensions.ReplicaSet, newRS *extensions.ReplicaSet, deployment *extensions.Deployment) (bool, error) {
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if *(newRS.Spec.Replicas) == *(deployment.Spec.Replicas) {
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// Scaling not required.
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return false, nil
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}
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if *(newRS.Spec.Replicas) > *(deployment.Spec.Replicas) {
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// Scale down.
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scaled, _, err := dc.scaleReplicaSetAndRecordEvent(newRS, *(deployment.Spec.Replicas), deployment)
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return scaled, err
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}
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newReplicasCount, err := deploymentutil.NewRSNewReplicas(deployment, allRSs, newRS)
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if err != nil {
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return false, err
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}
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scaled, _, err := dc.scaleReplicaSetAndRecordEvent(newRS, newReplicasCount, deployment)
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return scaled, err
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}
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func (dc *DeploymentController) reconcileOldReplicaSets(allRSs []*extensions.ReplicaSet, oldRSs []*extensions.ReplicaSet, newRS *extensions.ReplicaSet, deployment *extensions.Deployment) (bool, error) {
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oldPodsCount := deploymentutil.GetReplicaCountForReplicaSets(oldRSs)
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if oldPodsCount == 0 {
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// Can't scale down further
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return false, nil
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}
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allPodsCount := deploymentutil.GetReplicaCountForReplicaSets(allRSs)
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glog.V(4).Infof("New replica set %s/%s has %d available pods.", newRS.Namespace, newRS.Name, newRS.Status.AvailableReplicas)
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maxUnavailable := deploymentutil.MaxUnavailable(*deployment)
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// Check if we can scale down. We can scale down in the following 2 cases:
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// * Some old replica sets have unhealthy replicas, we could safely scale down those unhealthy replicas since that won't further
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// increase unavailability.
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// * New replica set has scaled up and it's replicas becomes ready, then we can scale down old replica sets in a further step.
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//
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// maxScaledDown := allPodsCount - minAvailable - newReplicaSetPodsUnavailable
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// take into account not only maxUnavailable and any surge pods that have been created, but also unavailable pods from
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// the newRS, so that the unavailable pods from the newRS would not make us scale down old replica sets in a further
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// step(that will increase unavailability).
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//
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// Concrete example:
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//
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// * 10 replicas
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// * 2 maxUnavailable (absolute number, not percent)
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// * 3 maxSurge (absolute number, not percent)
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//
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// case 1:
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// * Deployment is updated, newRS is created with 3 replicas, oldRS is scaled down to 8, and newRS is scaled up to 5.
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// * The new replica set pods crashloop and never become available.
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// * allPodsCount is 13. minAvailable is 8. newRSPodsUnavailable is 5.
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// * A node fails and causes one of the oldRS pods to become unavailable. However, 13 - 8 - 5 = 0, so the oldRS won't be scaled down.
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// * The user notices the crashloop and does kubectl rollout undo to rollback.
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// * newRSPodsUnavailable is 1, since we rolled back to the good replica set, so maxScaledDown = 13 - 8 - 1 = 4. 4 of the crashlooping pods will be scaled down.
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// * The total number of pods will then be 9 and the newRS can be scaled up to 10.
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//
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// case 2:
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// Same example, but pushing a new pod template instead of rolling back (aka "roll over"):
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// * The new replica set created must start with 0 replicas because allPodsCount is already at 13.
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// * However, newRSPodsUnavailable would also be 0, so the 2 old replica sets could be scaled down by 5 (13 - 8 - 0), which would then
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// allow the new replica set to be scaled up by 5.
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minAvailable := *(deployment.Spec.Replicas) - maxUnavailable
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newRSUnavailablePodCount := *(newRS.Spec.Replicas) - newRS.Status.AvailableReplicas
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maxScaledDown := allPodsCount - minAvailable - newRSUnavailablePodCount
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if maxScaledDown <= 0 {
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return false, nil
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}
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// Clean up unhealthy replicas first, otherwise unhealthy replicas will block deployment
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// and cause timeout. See https://github.com/kubernetes/kubernetes/issues/16737
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oldRSs, cleanupCount, err := dc.cleanupUnhealthyReplicas(oldRSs, deployment, maxScaledDown)
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if err != nil {
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return false, nil
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}
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glog.V(4).Infof("Cleaned up unhealthy replicas from old RSes by %d", cleanupCount)
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// Scale down old replica sets, need check maxUnavailable to ensure we can scale down
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allRSs = append(oldRSs, newRS)
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scaledDownCount, err := dc.scaleDownOldReplicaSetsForRollingUpdate(allRSs, oldRSs, deployment)
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if err != nil {
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return false, nil
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}
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glog.V(4).Infof("Scaled down old RSes of deployment %s by %d", deployment.Name, scaledDownCount)
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totalScaledDown := cleanupCount + scaledDownCount
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return totalScaledDown > 0, nil
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}
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// cleanupUnhealthyReplicas will scale down old replica sets with unhealthy replicas, so that all unhealthy replicas will be deleted.
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func (dc *DeploymentController) cleanupUnhealthyReplicas(oldRSs []*extensions.ReplicaSet, deployment *extensions.Deployment, maxCleanupCount int32) ([]*extensions.ReplicaSet, int32, error) {
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sort.Sort(controller.ReplicaSetsByCreationTimestamp(oldRSs))
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// Safely scale down all old replica sets with unhealthy replicas. Replica set will sort the pods in the order
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// such that not-ready < ready, unscheduled < scheduled, and pending < running. This ensures that unhealthy replicas will
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// been deleted first and won't increase unavailability.
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totalScaledDown := int32(0)
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for i, targetRS := range oldRSs {
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if totalScaledDown >= maxCleanupCount {
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break
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}
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if *(targetRS.Spec.Replicas) == 0 {
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// cannot scale down this replica set.
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continue
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}
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glog.V(4).Infof("Found %d available pods in old RS %s/%s", targetRS.Status.AvailableReplicas, targetRS.Namespace, targetRS.Name)
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if *(targetRS.Spec.Replicas) == targetRS.Status.AvailableReplicas {
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// no unhealthy replicas found, no scaling required.
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continue
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}
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scaledDownCount := int32(integer.IntMin(int(maxCleanupCount-totalScaledDown), int(*(targetRS.Spec.Replicas)-targetRS.Status.AvailableReplicas)))
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newReplicasCount := *(targetRS.Spec.Replicas) - scaledDownCount
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if newReplicasCount > *(targetRS.Spec.Replicas) {
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return nil, 0, fmt.Errorf("when cleaning up unhealthy replicas, got invalid request to scale down %s/%s %d -> %d", targetRS.Namespace, targetRS.Name, *(targetRS.Spec.Replicas), newReplicasCount)
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}
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_, updatedOldRS, err := dc.scaleReplicaSetAndRecordEvent(targetRS, newReplicasCount, deployment)
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if err != nil {
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return nil, totalScaledDown, err
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}
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totalScaledDown += scaledDownCount
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oldRSs[i] = updatedOldRS
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}
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return oldRSs, totalScaledDown, nil
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}
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// scaleDownOldReplicaSetsForRollingUpdate scales down old replica sets when deployment strategy is "RollingUpdate".
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// Need check maxUnavailable to ensure availability
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func (dc *DeploymentController) scaleDownOldReplicaSetsForRollingUpdate(allRSs []*extensions.ReplicaSet, oldRSs []*extensions.ReplicaSet, deployment *extensions.Deployment) (int32, error) {
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maxUnavailable := deploymentutil.MaxUnavailable(*deployment)
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// Check if we can scale down.
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minAvailable := *(deployment.Spec.Replicas) - maxUnavailable
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// Find the number of available pods.
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availablePodCount := deploymentutil.GetAvailableReplicaCountForReplicaSets(allRSs)
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if availablePodCount <= minAvailable {
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// Cannot scale down.
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return 0, nil
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}
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glog.V(4).Infof("Found %d available pods in deployment %s, scaling down old RSes", availablePodCount, deployment.Name)
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sort.Sort(controller.ReplicaSetsByCreationTimestamp(oldRSs))
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totalScaledDown := int32(0)
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totalScaleDownCount := availablePodCount - minAvailable
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for _, targetRS := range oldRSs {
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if totalScaledDown >= totalScaleDownCount {
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// No further scaling required.
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break
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}
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if *(targetRS.Spec.Replicas) == 0 {
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// cannot scale down this ReplicaSet.
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continue
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}
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// Scale down.
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scaleDownCount := int32(integer.IntMin(int(*(targetRS.Spec.Replicas)), int(totalScaleDownCount-totalScaledDown)))
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newReplicasCount := *(targetRS.Spec.Replicas) - scaleDownCount
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if newReplicasCount > *(targetRS.Spec.Replicas) {
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return 0, fmt.Errorf("when scaling down old RS, got invalid request to scale down %s/%s %d -> %d", targetRS.Namespace, targetRS.Name, *(targetRS.Spec.Replicas), newReplicasCount)
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}
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_, _, err := dc.scaleReplicaSetAndRecordEvent(targetRS, newReplicasCount, deployment)
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if err != nil {
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return totalScaledDown, err
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}
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totalScaledDown += scaleDownCount
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}
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return totalScaledDown, nil
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}
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