Filter pods by labelSelector

README.md

@@ -43,6 +43,7 @@ Table of Contents
  * [Filter Pods](#filter-pods)
  * [Namespace filtering](#namespace-filtering)
  * [Priority filtering](#priority-filtering)
+ * [Label filtering](#label-filtering)
  * [Pod Evictions](#pod-evictions)
  * [Pod Disruption Budget (PDB)](#pod-disruption-budget-pdb)
  * [Compatibility Matrix](#compatibility-matrix)
@@ -239,6 +240,7 @@ node.
 |`thresholdPriority`|int (see [priority filtering](#priority-filtering))|
 |`thresholdPriorityClassName`|string (see [priority filtering](#priority-filtering))|
 |`namespaces`|(see [namespace filtering](#namespace-filtering))|
+|`labelSelector`|(see [label filtering](#label-filtering))|
 
 **Example:**
 
@@ -276,6 +278,7 @@ podA gets evicted from nodeA.
 |`thresholdPriority`|int (see [priority filtering](#priority-filtering))|
 |`thresholdPriorityClassName`|string (see [priority filtering](#priority-filtering))|
 |`namespaces`|(see [namespace filtering](#namespace-filtering))|
+|`labelSelector`|(see [label filtering](#label-filtering))|
 
 **Example:**
 
@@ -304,6 +307,7 @@ and will be evicted.
 |`thresholdPriority`|int (see [priority filtering](#priority-filtering))|
 |`thresholdPriorityClassName`|string (see [priority filtering](#priority-filtering))|
 |`namespaces`|(see [namespace filtering](#namespace-filtering))|
+|`labelSelector`|(see [label filtering](#label-filtering))|
 
 **Example:**
 
@@ -352,6 +356,7 @@ This strategy makes sure that pods having too many restarts are removed from nod
 can't get the volume/disk attached to the instance, then the pod should be re-scheduled to other nodes. Its parameters 
 include `podRestartThreshold`, which is the number of restarts at which a pod should be evicted, and `includingInitContainers`, 
 which determines whether init container restarts should be factored into that calculation.
+|`labelSelector`|(see [label filtering](#label-filtering))|
 
 **Parameters:**
 
@@ -393,6 +398,7 @@ to `Running` and `Pending`.
 |`thresholdPriority`|int (see [priority filtering](#priority-filtering))|
 |`thresholdPriorityClassName`|string (see [priority filtering](#priority-filtering))|
 |`namespaces`|(see [namespace filtering](#namespace-filtering))|
+|`labelSelector`|(see [label filtering](#label-filtering))|
 
 **Example:**
 
@@ -498,6 +504,38 @@ strategies:
 Note that you can't configure both `thresholdPriority` and `thresholdPriorityClassName`, if the given priority class
 does not exist, descheduler won't create it and will throw an error.
 
+### Label filtering
+
+The following strategies can configure a [standard kubernetes labelSelector](https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.20/#labelselector-v1-meta)
+to filter pods by their labels:
+
+* `PodLifeTime`
+* `RemovePodsHavingTooManyRestarts`
+* `RemovePodsViolatingNodeTaints`
+* `RemovePodsViolatingNodeAffinity`
+* `RemovePodsViolatingInterPodAntiAffinity`
+
+This allows running strategies among pods the descheduler is interested in.
+
+For example:
+
+```yaml
+apiVersion: "descheduler/v1alpha1"
+kind: "DeschedulerPolicy"
+strategies:
+ "PodLifeTime":
+ enabled: true
+ params:
+ podLifeTime:
+ maxPodLifeTimeSeconds: 86400
+ labelSelector:
+ matchLabels:
+ component: redis
+ matchExpressions:
+ - {key: tier, operator: In, values: [cache]}
+ - {key: environment, operator: NotIn, values: [dev]}
+```
+
 ## Pod Evictions
 
 When the descheduler decides to evict pods from a node, it employs the following general mechanism:

pkg/api/types.go

@@ -76,6 +76,7 @@ type StrategyParameters struct {
  Namespaces *Namespaces
  ThresholdPriority *int32
  ThresholdPriorityClassName string
+ LabelSelector *metav1.LabelSelector
 }
 
 type Percentage float64

pkg/api/v1alpha1/types.go

@@ -74,6 +74,7 @@ type StrategyParameters struct {
  Namespaces *Namespaces `json:"namespaces"`
  ThresholdPriority *int32 `json:"thresholdPriority"`
  ThresholdPriorityClassName string `json:"thresholdPriorityClassName"`
+ LabelSelector *metav1.LabelSelector `json:"labelSelector"`
 }
 
 type Percentage float64

pkg/descheduler/pod/pods.go

@@ -31,6 +31,7 @@ type Options struct {
  filter func(pod *v1.Pod) bool
  includedNamespaces []string
  excludedNamespaces []string
+ labelSelector *metav1.LabelSelector
 }
 
 // WithFilter sets a pod filter.
@@ -55,6 +56,13 @@ func WithoutNamespaces(namespaces []string) func(opts *Options) {
  }
 }
 
+// WithLabelSelector sets a pod label selector
+func WithLabelSelector(labelSelector *metav1.LabelSelector) func(opts *Options) {
+ return func(opts *Options) {
+ opts.labelSelector = labelSelector
+ }
+}
+
 // ListPodsOnANode lists all of the pods on a node
 // It also accepts an optional "filter" function which can be used to further limit the pods that are returned.
 // (Usually this is podEvictor.Evictable().IsEvictable, in order to only list the evictable pods on a node, but can
@@ -74,6 +82,15 @@ func ListPodsOnANode(
 
  fieldSelectorString := "spec.nodeName=" + node.Name + ",status.phase!=" + string(v1.PodSucceeded) + ",status.phase!=" + string(v1.PodFailed)
 
+ labelSelectorString := ""
+ if options.labelSelector != nil {
+ selector, err := metav1.LabelSelectorAsSelector(options.labelSelector)
+ if err != nil {
+ return []*v1.Pod{}, err
+ }
+ labelSelectorString = selector.String()
+ }
+
  if len(options.includedNamespaces) > 0 {
  fieldSelector, err := fields.ParseSelector(fieldSelectorString)
  if err != nil {
@@ -82,7 +99,10 @@ func ListPodsOnANode(
 
  for _, namespace := range options.includedNamespaces {
  podList, err := client.CoreV1().Pods(namespace).List(ctx,
- metav1.ListOptions{FieldSelector: fieldSelector.String()})
+ metav1.ListOptions{
+ FieldSelector: fieldSelector.String(),
+ LabelSelector: labelSelectorString,
+ })
  if err != nil {
  return []*v1.Pod{}, err
  }
@@ -111,7 +131,10 @@ func ListPodsOnANode(
  // Once the descheduler switches to pod listers (through informers),
  // We need to flip to client-side filtering.
  podList, err := client.CoreV1().Pods(v1.NamespaceAll).List(ctx,
- metav1.ListOptions{FieldSelector: fieldSelector.String()})
+ metav1.ListOptions{
+ FieldSelector: fieldSelector.String(),
+ LabelSelector: labelSelectorString,
+ })
  if err != nil {
  return []*v1.Pod{}, err
  }

pkg/descheduler/pod/pods_test.go

@@ -24,6 +24,7 @@ import (
  "testing"
 
  v1 "k8s.io/api/core/v1"
+ metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
  "k8s.io/apimachinery/pkg/runtime"
  "k8s.io/client-go/kubernetes/fake"
  core "k8s.io/client-go/testing"
@@ -40,6 +41,7 @@ func TestListPodsOnANode(t *testing.T) {
  name string
  pods map[string][]v1.Pod
  node *v1.Node
+ labelSelector *metav1.LabelSelector
  expectedPodCount int
  }{
  {
@@ -52,6 +54,33 @@ func TestListPodsOnANode(t *testing.T) {
  "n2": {*test.BuildTestPod("pod3", 100, 0, "n2", nil)},
  },
  node: test.BuildTestNode("n1", 2000, 3000, 10, nil),
+ labelSelector: nil,
+ expectedPodCount: 2,
+ },
+ {
+ name: "test listing pods with label selector",
+ pods: map[string][]v1.Pod{
+ "n1": {
+ *test.BuildTestPod("pod1", 100, 0, "n1", nil),
+ *test.BuildTestPod("pod2", 100, 0, "n1", func(pod *v1.Pod) {
+ pod.Labels = map[string]string{"foo": "bar"}
+ }),
+ *test.BuildTestPod("pod3", 100, 0, "n1", func(pod *v1.Pod) {
+ pod.Labels = map[string]string{"foo": "bar1"}
+ }),
+ },
+ "n2": {*test.BuildTestPod("pod4", 100, 0, "n2", nil)},
+ },
+ node: test.BuildTestNode("n1", 2000, 3000, 10, nil),
+ labelSelector: &metav1.LabelSelector{
+ MatchExpressions: []metav1.LabelSelectorRequirement{
+ {
+ Key: "foo",
+ Operator: metav1.LabelSelectorOpIn,
+ Values: []string{"bar", "bar1"},
+ },
+ },
+ },
  expectedPodCount: 2,
  },
  }
@@ -67,7 +96,7 @@ func TestListPodsOnANode(t *testing.T) {
  }
  return true, nil, fmt.Errorf("Failed to list: %v", list)
  })
- pods, _ := ListPodsOnANode(context.TODO(), fakeClient, testCase.node)
+ pods, _ := ListPodsOnANode(context.TODO(), fakeClient, testCase.node, WithLabelSelector(testCase.labelSelector))
  if len(pods) != testCase.expectedPodCount {
  t.Errorf("expected %v pods on node %v, got %+v", testCase.expectedPodCount, testCase.node.Name, len(pods))
  }

pkg/descheduler/strategies/node_affinity.go

@@ -85,6 +85,7 @@ func RemovePodsViolatingNodeAffinity(ctx context.Context, client clientset.Inter
  }),
  podutil.WithNamespaces(includedNamespaces),
  podutil.WithoutNamespaces(excludedNamespaces),
+ podutil.WithLabelSelector(strategy.Params.LabelSelector),
  )
  if err != nil {
  klog.ErrorS(err, "Failed to get pods", "node", klog.KObj(node))

pkg/descheduler/strategies/node_taint.go

@@ -26,6 +26,7 @@ import (
  "sigs.k8s.io/descheduler/pkg/utils"
 
  v1 "k8s.io/api/core/v1"
+ metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
  clientset "k8s.io/client-go/kubernetes"
  "k8s.io/klog/v2"
 )
@@ -54,9 +55,13 @@ func RemovePodsViolatingNodeTaints(ctx context.Context, client clientset.Interfa
  }
 
  var includedNamespaces, excludedNamespaces []string
- if strategy.Params != nil && strategy.Params.Namespaces != nil {
- includedNamespaces = strategy.Params.Namespaces.Include
- excludedNamespaces = strategy.Params.Namespaces.Exclude
+ var labelSelector *metav1.LabelSelector
+ if strategy.Params != nil {
+ if strategy.Params.Namespaces != nil {
+ includedNamespaces = strategy.Params.Namespaces.Include
+ excludedNamespaces = strategy.Params.Namespaces.Exclude
+ }
+ labelSelector = strategy.Params.LabelSelector
  }
 
  thresholdPriority, err := utils.GetPriorityFromStrategyParams(ctx, client, strategy.Params)
@@ -76,6 +81,7 @@ func RemovePodsViolatingNodeTaints(ctx context.Context, client clientset.Interfa
  podutil.WithFilter(evictable.IsEvictable),
  podutil.WithNamespaces(includedNamespaces),
  podutil.WithoutNamespaces(excludedNamespaces),
+ podutil.WithLabelSelector(labelSelector),
  )
  if err != nil {
  //no pods evicted as error encountered retrieving evictable Pods

pkg/descheduler/strategies/pod_antiaffinity.go

@@ -55,9 +55,13 @@ func RemovePodsViolatingInterPodAntiAffinity(ctx context.Context, client clients
  }
 
  var includedNamespaces, excludedNamespaces []string
- if strategy.Params != nil && strategy.Params.Namespaces != nil {
- includedNamespaces = strategy.Params.Namespaces.Include
- excludedNamespaces = strategy.Params.Namespaces.Exclude
+ var labelSelector *metav1.LabelSelector
+ if strategy.Params != nil {
+ if strategy.Params.Namespaces != nil {
+ includedNamespaces = strategy.Params.Namespaces.Include
+ excludedNamespaces = strategy.Params.Namespaces.Exclude
+ }
+ labelSelector = strategy.Params.LabelSelector
  }
 
  thresholdPriority, err := utils.GetPriorityFromStrategyParams(ctx, client, strategy.Params)
@@ -76,6 +80,7 @@ func RemovePodsViolatingInterPodAntiAffinity(ctx context.Context, client clients
  node,
  podutil.WithNamespaces(includedNamespaces),
  podutil.WithoutNamespaces(excludedNamespaces),
+ podutil.WithLabelSelector(labelSelector),
  )
  if err != nil {
  return