Separate ScaleDown logic with a new interface

cluster-autoscaler/core/scaledown/deletiontracker/nodedeletiontracker.go

@@ -24,6 +24,7 @@ import (
 )
 
 // NodeDeletionTracker keeps track of node deletions.
+// TODO: extend to implement ActuationStatus interface
 type NodeDeletionTracker struct {
 	sync.Mutex
 	nonEmptyNodeDeleteInProgress bool

cluster-autoscaler/core/scaledown/legacy/wrapper.go

@@ -0,0 +1,137 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package legacy
+
+import (
+	"time"
+
+	"k8s.io/autoscaler/cluster-autoscaler/core/scaledown"
+	"k8s.io/autoscaler/cluster-autoscaler/core/scaledown/deletiontracker"
+	"k8s.io/autoscaler/cluster-autoscaler/processors/status"
+	"k8s.io/autoscaler/cluster-autoscaler/simulator"
+	"k8s.io/autoscaler/cluster-autoscaler/simulator/utilization"
+	"k8s.io/autoscaler/cluster-autoscaler/utils/errors"
+
+	apiv1 "k8s.io/api/core/v1"
+	policyv1 "k8s.io/api/policy/v1beta1"
+)
+
+// ScaleDownWrapper wraps legacy scaledown logic to satisfy scaledown.Planner &
+// scaledown.Actuator interfaces.
+type ScaleDownWrapper struct {
+	sd   *ScaleDown
+	pdbs []*policyv1.PodDisruptionBudget
+}
+
+// NewScaleDownWrapper returns a new ScaleDownWrapper
+func NewScaleDownWrapper(sd *ScaleDown) *ScaleDownWrapper {
+	return &ScaleDownWrapper{
+		sd: sd,
+	}
+}
+
+// UpdateClusterState updates unneeded nodes in the underlying ScaleDown.
+func (p *ScaleDownWrapper) UpdateClusterState(podDestinations, scaleDownCandidates []*apiv1.Node, actuationStatus scaledown.ActuationStatus, pdbs []*policyv1.PodDisruptionBudget, currentTime time.Time) errors.AutoscalerError {
+	p.sd.CleanUp(currentTime)
+	p.pdbs = pdbs
+	return p.sd.UpdateUnneededNodes(podDestinations, scaleDownCandidates, currentTime, pdbs)
+}
+
+// CleanUpUnneededNodes cleans up unneeded nodes.
+func (p *ScaleDownWrapper) CleanUpUnneededNodes() {
+	p.sd.CleanUpUnneededNodes()
+}
+
+// NodesToDelete lists nodes to delete. Current implementation is a no-op, the
+// wrapper leverages shared state instead.
+// TODO(x13n): Implement this and get rid of sharing state between planning and
+// actuation.
+func (p *ScaleDownWrapper) NodesToDelete() (empty, needDrain []*apiv1.Node) {
+	return nil, nil
+}
+
+// UnneededNodes returns a list of unneeded nodes.
+func (p *ScaleDownWrapper) UnneededNodes() []*apiv1.Node {
+	return p.sd.UnneededNodes()
+}
+
+// UnremovableNodes returns a list of nodes that cannot be removed.
+func (p *ScaleDownWrapper) UnremovableNodes() []*simulator.UnremovableNode {
+	return p.sd.UnremovableNodes()
+}
+
+// NodeUtilizationMap returns information about utilization of individual
+// cluster nodes.
+func (p *ScaleDownWrapper) NodeUtilizationMap() map[string]utilization.Info {
+	return p.sd.NodeUtilizationMap()
+}
+
+// StartDeletion triggers an actual scale down logic.
+func (p *ScaleDownWrapper) StartDeletion(empty, needDrain []*apiv1.Node, currentTime time.Time) (*status.ScaleDownStatus, errors.AutoscalerError) {
+	return p.sd.TryToScaleDown(currentTime, p.pdbs)
+}
+
+// CheckStatus snapshots current deletion status
+func (p *ScaleDownWrapper) CheckStatus() scaledown.ActuationStatus {
+	// TODO: snapshot information from the tracker instead of keeping live
+	// updated object.
+	return &actuationStatus{
+		ndt: p.sd.nodeDeletionTracker,
+	}
+}
+
+// ClearResultsNotNewerThan clears old node deletion results kept by the
+// Actuator.
+func (p *ScaleDownWrapper) ClearResultsNotNewerThan(t time.Time) {
+	// TODO: implement this once results are not cleared while being
+	// fetched.
+}
+
+type actuationStatus struct {
+	ndt *deletiontracker.NodeDeletionTracker
+}
+
+// DeletionsInProgress returns node names of currently deleted nodes.
+// Current implementation is not aware of the actual nodes names, so it returns
+// a fake node name instead.
+// TODO: Return real node names
+func (a *actuationStatus) DeletionsInProgress() []string {
+	if a.ndt.IsNonEmptyNodeDeleteInProgress() {
+		return []string{"fake-node-name"}
+	}
+	return nil
+}
+
+// DeletionsCount returns total number of ongoing deletions in a given node
+// group.
+func (a *actuationStatus) DeletionsCount(nodeGroupId string) int {
+	return a.ndt.GetDeletionsInProgress(nodeGroupId)
+}
+
+// RecentEvictions should return a list of recently evicted pods. Since legacy
+// scale down logic only drains at most one node at a time, this safeguard is
+// not really needed there, so we can just return an empty list.
+func (a *actuationStatus) RecentEvictions() []*apiv1.Pod {
+	return nil
+}
+
+// DeletionResults returns a map of recent node deletion results.
+func (a *actuationStatus) DeletionResults() map[string]status.NodeDeleteResult {
+	// TODO: update nodeDeletionTracker so it doesn't get & clear in the
+	// same step.
+	return a.ndt.GetAndClearNodeDeleteResults()
+}

cluster-autoscaler/core/scaledown/scaledown.go

@@ -0,0 +1,84 @@
+/*
+Copyright 2016 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package scaledown
+
+import (
+	"time"
+
+	"k8s.io/autoscaler/cluster-autoscaler/processors/status"
+	"k8s.io/autoscaler/cluster-autoscaler/simulator"
+	"k8s.io/autoscaler/cluster-autoscaler/simulator/utilization"
+	"k8s.io/autoscaler/cluster-autoscaler/utils/errors"
+
+	apiv1 "k8s.io/api/core/v1"
+	policyv1 "k8s.io/api/policy/v1beta1"
+)
+
+// Planner is responsible for selecting nodes that should be removed.
+type Planner interface {
+	// UpdateClusterState provides the Planner with information about the cluster.
+	UpdateClusterState(podDestinations, scaleDownCandidates []*apiv1.Node, as ActuationStatus, pdb []*policyv1.PodDisruptionBudget, currentTime time.Time) errors.AutoscalerError
+	// CleanUpUnneededNodes resets internal state of the Planner.
+	CleanUpUnneededNodes()
+	// NodesToDelete returns a list of nodes that can be deleted right now,
+	// according to the Planner.
+	NodesToDelete() (empty, needDrain []*apiv1.Node)
+	// UnneededNodes returns a list of nodes that either can be deleted
+	// right now or in a near future, assuming nothing will change in the
+	// cluster.
+	UnneededNodes() []*apiv1.Node
+	// UnremovableNodes returns a list of nodes that cannot be removed.
+	// TODO(x13n): Add a guarantee that each node is either unneeded or
+	// unremovable. This is not guaranteed by the current implementation.
+	UnremovableNodes() []*simulator.UnremovableNode
+	// NodeUtilizationMap returns information about utilization of
+	// individual cluster nodes.
+	NodeUtilizationMap() map[string]utilization.Info
+}
+
+// Actuator is responsible for making changes in the cluster: draining and
+// deleting nodes.
+type Actuator interface {
+	// StartDeletion triggers a new deletion process. Nodes passed to this
+	// function are not guaranteed to be deleted, it is possible for the
+	// Actuator to ignore some of them e.g. if max configured level of
+	// parallelism is reached.
+	StartDeletion(empty, needDrain []*apiv1.Node, currentTime time.Time) (*status.ScaleDownStatus, errors.AutoscalerError)
+	// CheckStatus returns an immutable snapshot of ongoing deletions.
+	CheckStatus() ActuationStatus
+	// ClearResultsNotNewerThan removes information about deletions finished
+	// before or exactly at the provided timestamp.
+	ClearResultsNotNewerThan(time.Time)
+}
+
+// ActuationStatus is used for feeding Actuator status back into Planner
+type ActuationStatus interface {
+	// DeletionsInProgress returns a list of nodes that are currently
+	// undergoing deletion.
+	DeletionsInProgress() (nodeNames []string)
+	// DeletionsCount returns total number of ongoing deletions in a given
+	// node group.
+	DeletionsCount(nodeGroupId string) int
+	// RecentEvictions returns a list of pods that were recently removed by
+	// the Actuator and hence are likely to get recreated elsewhere in the
+	// cluster.
+	RecentEvictions() (pods []*apiv1.Pod)
+	// DeletionResults returns a map of recent node deletion results, keyed
+	// by the node name. Note: if node deletion was scheduled more than
+	// once, only the latest result will be present.
+	DeletionResults() map[string]status.NodeDeleteResult
+}