Add RemovePodsViolatingNodeTaints taint exclusion

Add taint exclusion to RemovePodsViolatingNodeTaints. This permits node
taints to be ignored by allowing users to specify ignored taint keys or
ignored taint key=value pairs.

README.md

@@ -412,10 +412,17 @@ pod "podA" with a toleration to tolerate a taint ``key=value:NoSchedule`` schedu
 node. If the node's taint is subsequently updated/removed, taint is no longer satisfied by its pods' tolerations
 and will be evicted.
 
+Node taints can be excluded from consideration by specifying a list of excludedTaints. If a node taint key **or**
+key=value matches an excludedTaints entry, the taint will be ignored.
+
+For example, excludedTaints entry "dedicated" would match all taints with key "dedicated", regardless of value.
+excludedTaints entry "dedicated=special-user" would match taints with key "dedicated" and value "special-user".
+
 **Parameters:**
 
 |Name|Type|
 |---|---|
+|`excludedTaints`|list(string)|
 |`thresholdPriority`|int (see [priority filtering](#priority-filtering))|
 |`thresholdPriorityClassName`|string (see [priority filtering](#priority-filtering))|
 |`namespaces`|(see [namespace filtering](#namespace-filtering))|
@@ -430,6 +437,10 @@ kind: "DeschedulerPolicy"
 strategies:
   "RemovePodsViolatingNodeTaints":
     enabled: true
+    params:
+      excludedTaints:
+      - dedicated=special-user # exclude taints with key "dedicated" and value "special-user"
+      - reserved # exclude all taints with key "reserved"
 ````
 
 ### RemovePodsViolatingTopologySpreadConstraint

pkg/api/types.go

@@ -89,6 +89,7 @@ type StrategyParameters struct {
 	LabelSelector                     *metav1.LabelSelector
 	NodeFit                           bool
 	IncludePreferNoSchedule           bool
+	ExcludedTaints                    []string
 }
 
 type Percentage float64

pkg/api/v1alpha1/types.go

@@ -87,6 +87,7 @@ type StrategyParameters struct {
 	LabelSelector                     *metav1.LabelSelector              `json:"labelSelector"`
 	NodeFit                           bool                               `json:"nodeFit"`
 	IncludePreferNoSchedule           bool                               `json:"includePreferNoSchedule"`
+	ExcludedTaints                    []string                           `json:"excludedTaints,omitempty"`
 }
 
 type Percentage float64

pkg/api/v1alpha1/zz_generated.conversion.go

@@ -362,6 +362,7 @@ func autoConvert_v1alpha1_StrategyParameters_To_api_StrategyParameters(in *Strat
 	out.LabelSelector = (*v1.LabelSelector)(unsafe.Pointer(in.LabelSelector))
 	out.NodeFit = in.NodeFit
 	out.IncludePreferNoSchedule = in.IncludePreferNoSchedule
+	out.ExcludedTaints = *(*[]string)(unsafe.Pointer(&in.ExcludedTaints))
 	return nil
 }
 
@@ -384,6 +385,7 @@ func autoConvert_api_StrategyParameters_To_v1alpha1_StrategyParameters(in *api.S
 	out.LabelSelector = (*v1.LabelSelector)(unsafe.Pointer(in.LabelSelector))
 	out.NodeFit = in.NodeFit
 	out.IncludePreferNoSchedule = in.IncludePreferNoSchedule
+	out.ExcludedTaints = *(*[]string)(unsafe.Pointer(&in.ExcludedTaints))
 	return nil
 }
 

pkg/api/v1alpha1/zz_generated.deepcopy.go

@@ -356,6 +356,11 @@ func (in *StrategyParameters) DeepCopyInto(out *StrategyParameters) {
 		*out = new(v1.LabelSelector)
 		(*in).DeepCopyInto(*out)
 	}
+	if in.ExcludedTaints != nil {
+		in, out := &in.ExcludedTaints, &out.ExcludedTaints
+		*out = make([]string, len(*in))
+		copy(*out, *in)
+	}
 	return
 }
 

pkg/api/zz_generated.deepcopy.go

@@ -356,6 +356,11 @@ func (in *StrategyParameters) DeepCopyInto(out *StrategyParameters) {
 		*out = new(v1.LabelSelector)
 		(*in).DeepCopyInto(*out)
 	}
+	if in.ExcludedTaints != nil {
+		in, out := &in.ExcludedTaints, &out.ExcludedTaints
+		*out = make([]string, len(*in))
+		copy(*out, *in)
+	}
 	return
 }
 

pkg/descheduler/strategies/node_taint.go

@@ -55,13 +55,16 @@ func RemovePodsViolatingNodeTaints(ctx context.Context, client clientset.Interfa
 		return
 	}
 
-	var includedNamespaces, excludedNamespaces sets.String
+	var includedNamespaces, excludedNamespaces, excludedTaints sets.String
 	var labelSelector *metav1.LabelSelector
 	if strategy.Params != nil {
 		if strategy.Params.Namespaces != nil {
 			includedNamespaces = sets.NewString(strategy.Params.Namespaces.Include...)
 			excludedNamespaces = sets.NewString(strategy.Params.Namespaces.Exclude...)
 		}
+		if strategy.Params.ExcludedTaints != nil {
+			excludedTaints = sets.NewString(strategy.Params.ExcludedTaints...)
+		}
 		labelSelector = strategy.Params.LabelSelector
 	}
 
@@ -89,10 +92,15 @@ func RemovePodsViolatingNodeTaints(ctx context.Context, client clientset.Interfa
 		return
 	}
 
-	taintFilterFnc := func(taint *v1.Taint) bool { return taint.Effect == v1.TaintEffectNoSchedule }
+	excludeTaint := func(taint *v1.Taint) bool {
+		// Exclude taints by key *or* key=value
+		return excludedTaints.Has(taint.Key) || (taint.Value != "" && excludedTaints.Has(fmt.Sprintf("%s=%s", taint.Key, taint.Value)))
+	}
+
+	taintFilterFnc := func(taint *v1.Taint) bool { return (taint.Effect == v1.TaintEffectNoSchedule) && !excludeTaint(taint) }
 	if strategy.Params != nil && strategy.Params.IncludePreferNoSchedule {
 		taintFilterFnc = func(taint *v1.Taint) bool {
-			return taint.Effect == v1.TaintEffectNoSchedule || taint.Effect == v1.TaintEffectPreferNoSchedule
+			return (taint.Effect == v1.TaintEffectNoSchedule || taint.Effect == v1.TaintEffectPreferNoSchedule) && !excludeTaint(taint)
 		}
 	}
 

pkg/descheduler/strategies/node_taint_test.go

@@ -149,6 +149,7 @@ func TestDeletePodsViolatingNodeTaints(t *testing.T) {
 		expectedEvictedPodCount        uint
 		nodeFit                        bool
 		includePreferNoSchedule        bool
+		excludedTaints                 []string
 	}{
 
 		{
@@ -261,6 +262,33 @@ func TestDeletePodsViolatingNodeTaints(t *testing.T) {
 			includePreferNoSchedule: true,
 			expectedEvictedPodCount: 1, // p13 gets evicted
 		},
+		{
+			description:             "Pods not tolerating excluded node taints (by key) should not be evicted",
+			pods:                    []*v1.Pod{p2},
+			nodes:                   []*v1.Node{node1},
+			evictLocalStoragePods:   false,
+			evictSystemCriticalPods: false,
+			excludedTaints:          []string{"excludedTaint1", "testTaint1"},
+			expectedEvictedPodCount: 0, // nothing gets evicted, as one of the specified excludedTaints matches the key of node1's taint
+		},
+		{
+			description:             "Pods not tolerating excluded node taints (by key and value) should not be evicted",
+			pods:                    []*v1.Pod{p2},
+			nodes:                   []*v1.Node{node1},
+			evictLocalStoragePods:   false,
+			evictSystemCriticalPods: false,
+			excludedTaints:          []string{"testTaint1=test1"},
+			expectedEvictedPodCount: 0, // nothing gets evicted, as both the key and value of the excluded taint match node1's taint
+		},
+		{
+			description:             "The excluded taint matches the key of node1's taint, but does not match the value",
+			pods:                    []*v1.Pod{p2},
+			nodes:                   []*v1.Node{node1},
+			evictLocalStoragePods:   false,
+			evictSystemCriticalPods: false,
+			excludedTaints:          []string{"testTaint1=test2"},
+			expectedEvictedPodCount: 1, // pod gets evicted, as excluded taint value does not match node1's taint value
+		},
 	}
 
 	for _, tc := range tests {
@@ -307,6 +335,7 @@ func TestDeletePodsViolatingNodeTaints(t *testing.T) {
 				Params: &api.StrategyParameters{
 					NodeFit:                 tc.nodeFit,
 					IncludePreferNoSchedule: tc.includePreferNoSchedule,
+					ExcludedTaints:          tc.excludedTaints,
 				},
 			}