implement Node affinity and NodeSelector

plugin/pkg/scheduler/algorithm/predicates/predicates.go

@@ -343,12 +343,70 @@ func NewSelectorMatchPredicate(info NodeInfo) algorithm.FitPredicate {
 	return selector.PodSelectorMatches
 }
 
-func PodMatchesNodeLabels(pod *api.Pod, node *api.Node) bool {
-	if len(pod.Spec.NodeSelector) == 0 {
-		return true
+// NodeMatchesNodeSelectorTerms checks if a node's labels satisfy a list of node selector terms,
+// terms are ORed, and an emtpy a list of terms will match nothing.
+func NodeMatchesNodeSelectorTerms(node *api.Node, nodeSelectorTerms []api.NodeSelectorTerm) bool {
+	for _, req := range nodeSelectorTerms {
+		nodeSelector, err := api.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
+		}
 	}
-	selector := labels.SelectorFromSet(pod.Spec.NodeSelector)
-	return selector.Matches(labels.Set(node.Labels))
+	return false
+}
+
+// The pod can only schedule onto nodes that satisfy requirements in both NodeAffinity and nodeSelector.
+func PodMatchesNodeLabels(pod *api.Pod, node *api.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
+		}
+	}
+
+	// Parse required node affinity scheduling requirements
+	// and check if the current node match the requirements.
+	affinity, err := api.GetAffinityFromPodAnnotations(pod.Annotations)
+	if err != nil {
+		glog.V(10).Infof("Failed to get Affinity from Pod %+v, err: %+v", podName(pod), err)
+		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
+	nodeAffinityMatches := true
+	if affinity.NodeAffinity != nil {
+		nodeAffinity := affinity.NodeAffinity
+		// if no required NodeAffinity requirements, will do no-op, means select all nodes.
+		if nodeAffinity.RequiredDuringSchedulingRequiredDuringExecution == nil && nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution == nil {
+			return true
+		}
+
+		// Match node selector for requiredDuringSchedulingRequiredDuringExecution.
+		if nodeAffinity.RequiredDuringSchedulingRequiredDuringExecution != nil {
+			nodeSelectorTerms := nodeAffinity.RequiredDuringSchedulingRequiredDuringExecution.NodeSelectorTerms
+			glog.V(10).Infof("Match for RequiredDuringSchedulingRequiredDuringExecution node selector terms %+v", nodeSelectorTerms)
+			nodeAffinityMatches = NodeMatchesNodeSelectorTerms(node, nodeSelectorTerms)
+		}
+
+		// Match node selector for requiredDuringSchedulingRequiredDuringExecution.
+		if nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution != nil {
+			nodeSelectorTerms := nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms
+			glog.V(10).Infof("Match for RequiredDuringSchedulingIgnoredDuringExecution node selector terms %+v", nodeSelectorTerms)
+			nodeAffinityMatches = nodeAffinityMatches && NodeMatchesNodeSelectorTerms(node, nodeSelectorTerms)
+		}
+
+	}
+	return nodeAffinityMatches
 }
 
 type NodeSelector struct {