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predicates.go
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predicates.go
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// Unless explicitly stated otherwise all files in this repository are licensed
// under the Apache License Version 2.0.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright 2016-2019 Datadog, Inc.
// Package scheduler contains helper function around Daemonset pod scheduling.
package scheduler
import (
"fmt"
"github.com/go-logr/logr"
corev1 "k8s.io/api/core/v1"
"k8s.io/apimachinery/pkg/fields"
"k8s.io/apimachinery/pkg/labels"
"k8s.io/apimachinery/pkg/selection"
podaffinity "github.com/DataDog/extendeddaemonset/pkg/controller/utils/affinity"
)
// CheckNodeFitness runs a set of predicates that select candidate nodes for the DaemonSet;
// the predicates include:
// - PodMatchNodeSelector: checks pod's NodeSelector and NodeAffinity against node
// - PodToleratesNodeTaints: exclude tainted node unless pod has specific toleration
func CheckNodeFitness(logger logr.Logger, pod *corev1.Pod, node *corev1.Node) bool {
// Check pod node selector
// Check if node.Labels match pod.Spec.NodeSelector.
if !checkNodeSelector(pod, node) {
logger.V(1).Info("CheckNodeFitness return false", "reason", "node selector missmatch")
return false
}
if !checkPodToleratesNodeTaints(pod, node) {
logger.V(1).Info("CheckNodeFitness return false", "reason", "node taints")
return false
}
return true
}
func checkNodeSelector(pod *corev1.Pod, node *corev1.Node) bool {
if len(pod.Spec.NodeSelector) > 0 {
selector := labels.SelectorFromSet(pod.Spec.NodeSelector)
if !selector.Matches(labels.Set(node.Labels)) {
return false
}
}
// check node affinity
nodeAffinityMatches := true
if affinity := pod.Spec.Affinity; affinity != nil && affinity.NodeAffinity != nil {
nodeAffinity := affinity.NodeAffinity
if nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution == nil {
return true
}
// Match node selector for requiredDuringSchedulingIgnoredDuringExecution.
if nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution != nil {
nodeSelectorTerms := nodeAffinity.RequiredDuringSchedulingIgnoredDuringExecution.NodeSelectorTerms
nodeAffinityMatches = nodeAffinityMatches && nodeMatchesNodeSelectorTerms(node, nodeSelectorTerms)
}
}
return nodeAffinityMatches
}
func checkPodToleratesNodeTaints(pod *corev1.Pod, node *corev1.Node) bool {
filter := func(t *corev1.Taint) bool {
return t.Effect == corev1.TaintEffectNoSchedule || t.Effect == corev1.TaintEffectNoExecute
}
return TolerationsTolerateTaintsWithFilter(pod.Spec.Tolerations, node.Spec.Taints, filter)
}
// 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 *corev1.Node, nodeSelectorTerms []corev1.NodeSelectorTerm) bool {
nodeFields := map[string]string{
podaffinity.NodeFieldSelectorKeyNodeName: node.Name,
}
return MatchNodeSelectorTerms(nodeSelectorTerms, labels.Set(node.Labels), fields.Set(nodeFields))
}
type taintsFilterFunc func(*corev1.Taint) bool
// TolerationsTolerateTaintsWithFilter checks if given tolerations tolerates
// all the taints that apply to the filter in given taint list.
func TolerationsTolerateTaintsWithFilter(tolerations []corev1.Toleration, taints []corev1.Taint, applyFilter taintsFilterFunc) bool {
if len(taints) == 0 {
return true
}
for i := range taints {
if applyFilter != nil && !applyFilter(&taints[i]) {
continue
}
if !TolerationsTolerateTaint(tolerations, &taints[i]) {
return false
}
}
return true
}
// TolerationsTolerateTaint checks if taint is tolerated by any of the tolerations.
func TolerationsTolerateTaint(tolerations []corev1.Toleration, taint *corev1.Taint) bool {
for i := range tolerations {
if tolerations[i].ToleratesTaint(taint) {
return true
}
}
return false
}
// MatchNodeSelectorTerms checks whether the node labels and fields match node selector terms in ORed;
// nil or empty term matches no objects.
func MatchNodeSelectorTerms(
nodeSelectorTerms []corev1.NodeSelectorTerm,
nodeLabels, nodeFields labels.Labels,
) bool {
for _, req := range nodeSelectorTerms {
// nil or empty term selects no objects
if len(req.MatchExpressions) == 0 && len(req.MatchFields) == 0 {
continue
}
if len(req.MatchExpressions) != 0 {
labelSelector, err := NodeSelectorRequirementsAsSelector(req.MatchExpressions)
if err != nil || !labelSelector.Matches(nodeLabels) {
continue
}
}
if len(req.MatchFields) != 0 {
fieldSelector, err := NodeSelectorRequirementsAsFieldSelector(req.MatchFields)
if err != nil || !fieldSelector.Matches(nodeFields) {
continue
}
}
return true
}
return false
}
// NodeSelectorRequirementsAsSelector converts the []NodeSelectorRequirement api type into a struct that implements
// labels.Selector.
func NodeSelectorRequirementsAsSelector(nsm []corev1.NodeSelectorRequirement) (labels.Selector, error) {
if len(nsm) == 0 {
return labels.Nothing(), nil
}
selector := labels.NewSelector()
for _, expr := range nsm {
var op selection.Operator
switch expr.Operator {
case corev1.NodeSelectorOpIn:
op = selection.In
case corev1.NodeSelectorOpNotIn:
op = selection.NotIn
case corev1.NodeSelectorOpExists:
op = selection.Exists
case corev1.NodeSelectorOpDoesNotExist:
op = selection.DoesNotExist
case corev1.NodeSelectorOpGt:
op = selection.GreaterThan
case corev1.NodeSelectorOpLt:
op = selection.LessThan
default:
return nil, fmt.Errorf("%q is not a valid node selector operator", expr.Operator)
}
r, err := labels.NewRequirement(expr.Key, op, expr.Values)
if err != nil {
return nil, err
}
selector = selector.Add(*r)
}
return selector, nil
}
// NodeSelectorRequirementsAsFieldSelector converts the []NodeSelectorRequirement core type into a struct that implements
// fields.Selector.
func NodeSelectorRequirementsAsFieldSelector(nsm []corev1.NodeSelectorRequirement) (fields.Selector, error) {
if len(nsm) == 0 {
return fields.Nothing(), nil
}
selectors := []fields.Selector{}
for _, expr := range nsm {
switch expr.Operator {
case corev1.NodeSelectorOpIn:
if len(expr.Values) != 1 {
return nil, fmt.Errorf("unexpected number of value (%d) for node field selector operator %q",
len(expr.Values), expr.Operator)
}
selectors = append(selectors, fields.OneTermEqualSelector(expr.Key, expr.Values[0]))
case corev1.NodeSelectorOpNotIn:
if len(expr.Values) != 1 {
return nil, fmt.Errorf("unexpected number of value (%d) for node field selector operator %q",
len(expr.Values), expr.Operator)
}
selectors = append(selectors, fields.OneTermNotEqualSelector(expr.Key, expr.Values[0]))
default:
return nil, fmt.Errorf("%q is not a valid node field selector operator", expr.Operator)
}
}
return fields.AndSelectors(selectors...), nil
}