k8s scheduler plugin简单分析

k8s scheduler plugin

例子

cmd/main.go 中

func main() {
  ...
    command := app.NewSchedulerCommand(
        app.WithPlugin(coscheduling.Name, coscheduling.New),
        app.WithPlugin(qos.Name, qos.New),
    )
    if err := command.Execute(); err != nil {
        os.Exit(1)
    }
}

scheduler-plugins/pkg/qos/queue_sort.go 中

package qos

import (
    v1 "k8s.io/api/core/v1"
    "k8s.io/apimachinery/pkg/runtime"
    "k8s.io/kubernetes/pkg/api/v1/pod"
    v1qos "k8s.io/kubernetes/pkg/apis/core/v1/helper/qos"
    framework "k8s.io/kubernetes/pkg/scheduler/framework/v1alpha1"
)

// Name is the name of the plugin used in the plugin registry and configurations.
const Name = "QOSSort"

// Sort is a plugin that implements QoS class based sorting.
type Sort struct{}

var _ framework.QueueSortPlugin = &Sort{}

// Name returns name of the plugin.
func (pl *Sort) Name() string {
    return Name
}

// Less is the function used by the activeQ heap algorithm to sort pods.
// It sorts pods based on their priorities. When the priorities are equal, it uses
// the Pod QoS classes to break the tie.
func (*Sort) Less(pInfo1, pInfo2 *framework.PodInfo) bool {
    p1 := pod.GetPodPriority(pInfo1.Pod)
    p2 := pod.GetPodPriority(pInfo2.Pod)
    return (p1 > p2) || (p1 == p2 && compQOS(pInfo1.Pod, pInfo2.Pod))
}

func compQOS(p1, p2 *v1.Pod) bool {
    p1QOS, p2QOS := v1qos.GetPodQOS(p1), v1qos.GetPodQOS(p2)
    if p1QOS == v1.PodQOSGuaranteed {
        return true
    } else if p1QOS == v1.PodQOSBurstable {
        return p2QOS != v1.PodQOSGuaranteed
    } else {
        return p2QOS == v1.PodQOSBestEffort
    }
}

// New initializes a new plugin and returns it.
func New(_ *runtime.Unknown, _ framework.FrameworkHandle) (framework.Plugin, error) {
    return &Sort{}, nil
}

结合上文
pkg/scheduler/framework/runtime/framework.go 中

RunPreFilterPlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod) (status *framework.Status)
RunFilterPlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeInfo *framework.NodeInfo) framework.PluginToStatus
RunPostFilterPlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod, filteredNodeStatusMap framework.NodeToStatusMap)
RunReservePluginsReserve(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string)
RunReservePluginsUnreserve(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string)
RunPreScorePlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodes []*v1.Node) (status *framework.Status)
RunScorePlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodes []*v1.Node) (ps framework.PluginToNodeScores, status *framework.Status)
RunPreBindPlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string) (status *framework.Status)
RunBindPlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string) (status *framework.Status)
RunPostBindPlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string)
RunPermitPlugins(ctx context.Context, state *framework.CycleState, pod *v1.Pod, nodeName string) (status *framework.Status)
Less(*QueuedPodInfo, *QueuedPodInfo) bool

所有扩展点在 pkg/scheduler/framework/runtime/framework.go 中

func (f *frameworkImpl) getExtensionPoints(plugins *config.Plugins) []extensionPoint {
    return []extensionPoint{
        {plugins.PreFilter, &f.preFilterPlugins},
        {plugins.Filter, &f.filterPlugins},
        {plugins.PostFilter, &f.postFilterPlugins},
        {plugins.Reserve, &f.reservePlugins},
        {plugins.PreScore, &f.preScorePlugins},
        {plugins.Score, &f.scorePlugins},
        {plugins.PreBind, &f.preBindPlugins},
        {plugins.Bind, &f.bindPlugins},
        {plugins.PostBind, &f.postBindPlugins},
        {plugins.Permit, &f.permitPlugins},
        {plugins.QueueSort, &f.queueSortPlugins},
    }
}

这个例子实现了 QueueSortPlugin