改造 Kubernetes 自定义调度器
作者：快乐非自愿限量之名
- 2024-05-27 福建
本文字数：4546 字
阅读完需：约 15 分钟
Overview
Kubernetes 默认调度器在调度 Pod 时并不关心特殊资源例如磁盘、GPU 等，因此突发奇想来改造调度器，在翻阅官方调度器框架[1]、调度器配置[2]和参考大佬的文章[3]后，自己也来尝试改写一下。
环境配置
相关软件版本：
Kubernetes 版本：v1.19.0
Docker 版本：v26.1.2
Prometheus 版本：v2.49
Node Exporter 版本：v1.7.0
集群内有 1 个 master 和 3 个 node。
实验部分
项目总览
项目结构如下：
.├── Dockerfile├── deployment.yaml├── go.mod├── go.sum├── main.go├── pkg│ ├── cpu│ │ └── cputraffic.go│ ├── disk│ │ └── disktraffic.go│ ├── diskspace│ │ └── diskspacetraffic.go│ ├── memory│ │ └── memorytraffic.go│ ├── network│ │ └── networktraffic.go│ └── prometheus.go├── scheduler├── scheduler.conf└── scheduler.yaml复制代码
插件部分
下面以构建内存插件为例。
定义插件名称、变量和结构体
const MemoryPlugin = "MemoryTraffic"var _ = framework.ScorePlugin(&MemoryTraffic{})
type MemoryTraffic struct { prometheus *pkg.PrometheusHandle handle framework.FrameworkHandle}复制代码
下面来实现 framework.FrameworkHandle 的接口。
先定义插件初始化入口
func New(plArgs runtime.Object, h framework.FrameworkHandle) (framework.Plugin, error) { args := &MemoryTrafficArgs{} if err := fruntime.DecodeInto(plArgs, args); err != nil { return nil, err }
klog.Infof("[MemoryTraffic] args received. Device: %s; TimeRange: %d, Address: %s", args.DeviceName, args.TimeRange, args.IP)
return &MemoryTraffic{ handle: h, prometheus: pkg.NewProme(args.IP, args.DeviceName, time.Minute*time.Duration(args.TimeRange)), }, nil}复制代码
实现 Score 接口，Score 进行初步打分
func (n *MemoryTraffic) Score(ctx context.Context, state *framework.CycleState, p *corev1.Pod, nodeName string) (int64, *framework.Status) { nodeBandwidth, err := n.prometheus.MemoryGetGauge(nodeName) if err != nil { return 0, framework.NewStatus(framework.Error, fmt.Sprintf("error getting node bandwidth measure: %s", err)) } bandWidth := int64(nodeBandwidth.Value) klog.Infof("[MemoryTraffic] node '%s' bandwidth: %v", nodeName, bandWidth) return bandWidth, nil}
复制代码
实现 NormalizeScore，对上一步 Score 的打分进行修正
func (n *MemoryTraffic) NormalizeScore(ctx context.Context, state *framework.CycleState, pod *corev1.Pod, scores framework.NodeScoreList) *framework.Status { var higherScore int64 for _, node := range scores { if higherScore < node.Score { higherScore = node.Score } } // 计算公式为，满分 - (当前内存使用 / 总内存 * 100) // 公式的计算结果为，内存使用率越大的节点，分数越低 for i, node := range scores { scores[i].Score = node.Score * 100 / higherScore klog.Infof("[MemoryTraffic] Nodes final score: %v", scores[i].Score) }
klog.Infof("[MemoryTraffic] Nodes final score: %v", scores) return nil}复制代码
配置插件名称和返回 ScoreExtension
func (n *MemoryTraffic) Name() string { return MemoryPlugin}
// 如果返回framework.ScoreExtensions 就需要实现framework.ScoreExtensionsfunc (n *MemoryTraffic) ScoreExtensions() framework.ScoreExtensions { return n}复制代码
Prometheus 部分
首先来编写查询内存可用率的 PromQL
const memoryMeasureQueryTemplate = ` (avg_over_time(node_memory_MemAvailable_bytes[30m]) / avg_over_time(node_memory_MemTotal_bytes[30m])) * 100 * on(instance) group_left(nodename) (node_uname_info{nodename="%s"})`复制代码
然后来声明 PrometheusHandle
type PrometheusHandle struct { deviceName string timeRange time.Duration ip string client v1.API}复制代码
另外在插件部分也要声明查询 Prometheus 的参数结构体
type MemoryTrafficArgs struct { IP string `json:"ip"` DeviceName string `json:"deviceName"` TimeRange int `json:"timeRange"`}复制代码
编写初始化 Prometheus 插件入口
func NewProme(ip, deviceName string, timeRace time.Duration) *PrometheusHandle { client, err := api.NewClient(api.Config{Address: ip}) if err != nil { klog.Fatalf("[Prometheus Plugin] FatalError creating prometheus client: %s", err.Error()) } return &PrometheusHandle{ deviceName: deviceName, ip: ip, timeRange: timeRace, client: v1.NewAPI(client), }}复制代码
编写通用查询接口，可供其他类型资源查询
func (p *PrometheusHandle) query(promQL string) (model.Value, error) { results, warnings, err := p.client.Query(context.Background(), promQL, time.Now()) if len(warnings) > 0 { klog.Warningf("[Prometheus Query Plugin] Warnings: %v\n", warnings) }
return results, err}复制代码
获取内存可用率接口
func (p *PrometheusHandle) MemoryGetGauge(node string) (*model.Sample, error) { value, err := p.query(fmt.Sprintf(memoryMeasureQueryTemplate, node)) fmt.Println(fmt.Sprintf(memoryMeasureQueryTemplate, node)) if err != nil { return nil, fmt.Errorf("[MemoryTraffic Plugin] Error querying prometheus: %w", err) }
nodeMeasure := value.(model.Vector) if len(nodeMeasure) != 1 { return nil, fmt.Errorf("[MemoryTraffic Plugin] Invalid response, expected 1 value, got %d", len(nodeMeasure)) } return nodeMeasure[0], nil
}复制代码
然后在程序入口里启用插件并执行
func main() { rand.Seed(time.Now().UnixNano()) command := app.NewSchedulerCommand( app.WithPlugin(network.NetworkPlugin, network.New), app.WithPlugin(disk.DiskPlugin, disk.New), app.WithPlugin(diskspace.DiskSpacePlugin, diskspace.New), app.WithPlugin(cpu.CPUPlugin, cpu.New), app.WithPlugin(memory.MemoryPlugin, memory.New), ) // 对于外部注册一个plugin // command := app.NewSchedulerCommand( // app.WithPlugin("example-plugin1", ExamplePlugin1.New))
if err := command.Execute(); err != nil { fmt.Fprintf(os.Stderr, "%v\n", err) os.Exit(1) }}复制代码
配置部分
为方便观察，这里使用二进制方式运行，准备运行时的配置文件
apiVersion: kubescheduler.config.k8s.io/v1beta1kind: KubeSchedulerConfigurationclientConnection: kubeconfig: /etc/kubernetes/scheduler.confprofiles:- schedulerName: custom-scheduler plugins: score: enabled: - name: "CPUTraffic" weight: 3 - name: "MemoryTraffic" weight: 4 - name: "DiskSpaceTraffic" weight: 3 - name: "NetworkTraffic" weight: 2 disabled: - name: "*" pluginConfig: - name: "NetworkTraffic" args: ip: "http://172.19.32.140:9090" deviceName: "eth0" timeRange: 60 - name: "CPUTraffic" args: ip: "http://172.19.32.140:9090" deviceName: "eth0" timeRange: 0 - name: "MemoryTraffic" args: ip: "http://172.19.32.140:9090" deviceName: "eth0" timeRange: 0 - name: "DiskSpaceTraffic" args: ip: "http://172.19.32.140:9090" deviceName: "eth0" timeRange: 0复制代码
kubeconfig 处为 master 节点的 scheduler.conf，以实际路径为准，内包含集群的证书哈希，ip 为部署 Prometheus 节点的 ip，端口为 Promenade 配置中对外暴露的端口。
将二进制文件和 scheduler.yaml 放至 master 同一目录下运行：
./scheduler --logtostderr=true \ --address=127.0.0.1 \ --v=6 \ --config=`pwd`/scheduler.yaml \ --kubeconfig="/etc/kubernetes/scheduler.conf" \复制代码
验证结果
准备一个要部署的 Pod，使用指定的调度器名称
apiVersion: apps/v1kind: Deploymentmetadata: name: gin namespace: default labels: app: ginspec: replicas: 2 selector: matchLabels: app: gin template: metadata: labels: app: gin spec: schedulerName: my-custom-scheduler # 使用自定义调度器 containers: - name: gin image: jaydenchang/k8s_test:latest imagePullPolicy: Always command: ["./app"] ports: - containerPort: 9999 protocol: TCP复制代码
最后的可以查看日志，部分日志如下：
I0808 17:32:35.138289 27131 memorytraffic.go:83] [MemoryTraffic] node 'node1' bandwidth: %!s(int64=2680340)I0808 17:32:35.138763 27131 memorytraffic.go:70] [MemoryTraffic] Nodes final score: [{node1 2680340} {node2 0}]I0808 17:32:35.138851 27131 memorytraffic.go:70] [MemoryTraffic] Nodes final score: [{node1 71} {node2 0}]I0808 17:32:35.138911 27131 memorytraffic.go:73] [MemoryTraffic] Nodes final score: [{node1 71} {node2 0}]I0808 17:32:35.139565 27131 default_binder.go:51] Attempting to bind default/go-deployment-66878c4885-b4b7k to node1I0808 17:32:35.141114 27131 eventhandlers.go:225] add event for scheduled pod default/go-deployment-66878c4885-b4b7kI0808 17:32:35.141714 27131 eventhandlers.go:205] delete event for unscheduled pod default/go-deployment-66878c4885-b4b7kI0808 17:32:35.143504 27131 scheduler.go:609] "Successfully bound pod to node" pod="default/go-deployment-66878c4885-b4b7k" node="node1" evaluatedNodes=2 feasibleNodes=2I0808 17:32:35.104540 27131 scheduler.go:609] "Successfully bound pod to node" pod="default/go-deployment-66878c4885-b4b7k" node="node1" evaluatedNodes=2 feasibleNodes=2复制代码
文章转载自：JaydenChang
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