Update README and add priority/namespace filtering

README.md

@@ -97,7 +97,7 @@ The policy also includes common configuration for all the strategies:
 - `evictLocalStoragePods` - allowing to evict pods with local storage
 - `maxNoOfPodsToEvictPerNode` - maximum number of pods evicted from each node (summed through all strategies)
 
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 nodeSelector: prod=dev
@@ -129,7 +129,7 @@ has any of these `Kind`s listed as an `OwnerRef`, that pod will not be considere
 |`thresholdPriorityClassName`|string (see [priority filtering](#priority-filtering))|
 
 **Example:**
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -171,7 +171,7 @@ These thresholds, `thresholds` and `targetThresholds`, could be tuned as per you
 
 **Example:**
 
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -221,7 +221,7 @@ node.
 
 **Example:**
 
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -258,7 +258,7 @@ podA gets evicted from nodeA.
 
 **Example:**
 
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -286,7 +286,7 @@ and will be evicted.
 
 **Example:**
 
-````
+````yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -297,15 +297,25 @@ strategies:
 ### RemovePodsViolatingTopologySpreadConstraint
 
 This strategy makes sure that pods violating [topology spread constraints](https://kubernetes.io/docs/concepts/workloads/pods/pod-topology-spread-constraints/)
-are evicted from nodes. This strategy requires k8s version 1.18 at a minimum. To disable this strategy, the
-policy should look like:
+are evicted from nodes. Specifically, it tries to evict the minimum number of pods required to balance topology domains to within each constraint's `maxSkew`.
+This strategy requires k8s version 1.18 at a minimum.
 
-```
+**Parameters:**
+
+|Name|Type|
+|---|---|
+|`thresholdPriority`|int (see [priority filtering](#priority-filtering))|
+|`thresholdPriorityClassName`|string (see [priority filtering](#priority-filtering))|
+|`namespaces`|(see [namespace filtering](#namespace-filtering))|
+
+**Example:**
+
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
   "RemovePodsViolatingTopologySpreadConstraint":
-     enabled: false
+     enabled: true
 ```
 
 
@@ -328,7 +338,7 @@ which determines whether init container restarts should be factored into that ca
 
 **Example:**
 
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -359,7 +369,7 @@ to `Running` and `Pending`.
 
 **Example:**
 
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -386,7 +396,7 @@ The following strategies accept a `namespaces` parameter which allows to specify
 
 For example:
 
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -404,7 +414,7 @@ strategies:
 In the examples `PodLifeTime` gets executed only over `namespace1` and `namespace2`.
 The similar holds for `exclude` field:
 
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -432,7 +442,7 @@ is set to the value of `system-cluster-critical` priority class.
 E.g.
 
 Setting `thresholdPriority`
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:
@@ -445,7 +455,7 @@ strategies:
 ```
 
 Setting `thresholdPriorityClassName`
-```
+```yaml
 apiVersion: "descheduler/v1alpha1"
 kind: "DeschedulerPolicy"
 strategies:

pkg/descheduler/strategies/topologyspreadconstraint.go

@@ -18,14 +18,17 @@ package strategies
 
 import (
 	"context"
+	"fmt"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/apimachinery/pkg/util/sets"
 	clientset "k8s.io/client-go/kubernetes"
 	"k8s.io/klog/v2"
 	"math"
 	"sigs.k8s.io/descheduler/pkg/api"
 	"sigs.k8s.io/descheduler/pkg/descheduler/evictions"
+	"sigs.k8s.io/descheduler/pkg/utils"
 	"sort"
 )
 
@@ -40,18 +43,47 @@ type topology struct {
 	pods []*v1.Pod
 }
 
+func validateTopologySpreadParams(params *api.StrategyParameters) error {
+	// At most one of include/exclude can be set
+	if params.Namespaces != nil && len(params.Namespaces.Include) > 0 && len(params.Namespaces.Exclude) > 0 {
+		return fmt.Errorf("only one of Include/Exclude namespaces can be set")
+	}
+	if params.ThresholdPriority != nil && params.ThresholdPriorityClassName != "" {
+		return fmt.Errorf("only one of thresholdPriority and thresholdPriorityClassName can be set")
+	}
+
+	return nil
+}
+
 func RemovePodsViolatingTopologySpreadConstraint(
 	ctx context.Context,
 	client clientset.Interface,
 	strategy api.DeschedulerStrategy,
 	nodes []*v1.Node,
 	podEvictor *evictions.PodEvictor,
 ) {
+	if err := validateTopologySpreadParams(strategy.Params); err != nil {
+		klog.ErrorS(err, "Invalid PodLifeTime parameters")
+		return
+	}
+
+	thresholdPriority, err := utils.GetPriorityFromStrategyParams(ctx, client, strategy.Params)
+	if err != nil {
+		klog.ErrorS(err, "Failed to get threshold priority from strategy's params")
+		return
+	}
+
+	var includedNamespaces, excludedNamespaces sets.String
+	if strategy.Params.Namespaces != nil {
+		includedNamespaces = sets.NewString(strategy.Params.Namespaces.Include...)
+		excludedNamespaces = sets.NewString(strategy.Params.Namespaces.Exclude...)
+	}
+
 	nodeMap := make(map[string]*v1.Node, len(nodes))
 	for _, node := range nodes {
 		nodeMap[node.Name] = node
 	}
-	evictable := podEvictor.Evictable()
+	evictable := podEvictor.Evictable(evictions.WithPriorityThreshold(thresholdPriority))
 
 	// 1. for each namespace for which there is Topology Constraint
 	// 2. for each TopologySpreadyConstraint in that namespace
@@ -74,6 +106,9 @@ func RemovePodsViolatingTopologySpreadConstraint(
 	podsForEviction := make(map[*v1.Pod]struct{})
 	// 1. for each namespace...
 	for _, namespace := range namespaces.Items {
+		if (!includedNamespaces.Has(namespace.Name) || excludedNamespaces.Has(namespace.Name)) && (includedNamespaces.Len()+excludedNamespaces.Len() > 0) {
+			continue
+		}
 		namespacePods, err := client.CoreV1().Pods(namespace.Name).List(ctx, metav1.ListOptions{})
 		if err != nil {
 			klog.ErrorS(err, "Couldn't list pods in namespace", "namespace", namespace)
@@ -196,7 +231,7 @@ func RemovePodsViolatingTopologySpreadConstraint(
 					// (This is the basic principle of keeping all sizes within ~skew of the average)
 					movePods := int(math.Min(
 						math.Min(math.Ceil(skew/2), float64(len(sortedTopologies[j].pods)-idealAvg)),
-						float64(idealAvg - len(sortedTopologies[i].pods))))
+						float64(idealAvg-len(sortedTopologies[i].pods))))
 					if movePods <= 0 {
 						i++
 						continue