add RemovePodsViolatingNodeAffinity strategy

This commit adds requiredDuringSchedulingIgnoredDuringExecution
for RemovePodsViolatingNodeAffinity strategy.

Also adds unit tests and documentation.

pkg/utils/predicates.go

@@ -0,0 +1,94 @@
+/*
+Copyright 2017 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 utils
+
+import (
+	"fmt"
+
+	"github.com/golang/glog"
+	"k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	v1helper "k8s.io/kubernetes/pkg/apis/core/v1/helper"
+)
+
+// The following code has been copied from predicates package to avoid the
+// huge vendoring issues, mostly copied from
+// k8s.io/kubernetes/plugin/pkg/scheduler/algorithm/predicates/
+// Some minor changes have been made to ease the imports, but most of the code
+// remains untouched
+
+// PodMatchNodeSelector checks if a pod node selector matches the node label.
+func PodMatchNodeSelector(pod *v1.Pod, node *v1.Node) (bool, error) {
+	if node == nil {
+		return false, fmt.Errorf("node not found")
+	}
+	if podMatchesNodeLabels(pod, node) {
+		return true, nil
+	}
+	return false, nil
+}
+
+// The pod can only schedule onto nodes that satisfy requirements in both NodeAffinity and nodeSelector.
+func podMatchesNodeLabels(pod *v1.Pod, node *v1.Node) bool {
+	// Check if node.Labels match pod.Spec.NodeSelector.
+	if len(pod.Spec.NodeSelector) > 0 {
+		selector := labels.SelectorFromSet(pod.Spec.NodeSelector)
+		if !selector.Matches(labels.Set(node.Labels)) {
+			return false
+		}
+	}
+
+	// 1. nil NodeSelector matches all nodes (i.e. does not filter out any nodes)
+	// 2. nil []NodeSelectorTerm (equivalent to non-nil empty NodeSelector) matches no nodes
+	// 3. zero-length non-nil []NodeSelectorTerm matches no nodes also, just for simplicity
+	// 4. nil []NodeSelectorRequirement (equivalent to non-nil empty NodeSelectorTerm) matches no nodes
+	// 5. zero-length non-nil []NodeSelectorRequirement matches no nodes also, just for simplicity
+	// 6. non-nil empty NodeSelectorRequirement is not allowed
+
+	affinity := pod.Spec.Affinity
+	if affinity != nil && affinity.NodeAffinity != nil {
+		nodeAffinity := affinity.NodeAffinity
+		// if no required NodeAffinity requirements, will do no-op, means select all nodes.
+		if nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution == nil {
+			return true
+		}
+
+		// Match node selector for requiredDuringSchedulingIgnoredDuringExecution.
+		if nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution != nil {
+			nodeSelectorTerms := nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms
+			glog.V(10).Infof("Match for RequiredDuringSchedulingIgnoredDuringExecution node selector terms %+v", nodeSelectorTerms)
+			return nodeMatchesNodeSelectorTerms(node, nodeSelectorTerms)
+		}
+	}
+	return true
+}
+
+// nodeMatchesNodeSelectorTerms checks if a node's labels satisfy a list of node selector terms,
+// terms are ORed, and an empty list of terms will match nothing.
+func nodeMatchesNodeSelectorTerms(node *v1.Node, nodeSelectorTerms []v1.NodeSelectorTerm) bool {
+	for _, req := range nodeSelectorTerms {
+		nodeSelector, err := v1helper.NodeSelectorRequirementsAsSelector(req.MatchExpressions)
+		if err != nil {
+			glog.V(10).Infof("Failed to parse MatchExpressions: %+v, regarding as not match.", req.MatchExpressions)
+			return false
+		}
+		if nodeSelector.Matches(labels.Set(node.Labels)) {
+			return true
+		}
+	}
+	return false
+}