Kubernetes19--kube-scheduler源码4--Scheduler算法注册

研究一下kube-scheduler是如何构建Scheduler对象以及如何进行算法插件式注入

代码入口kubernetes\cmd\kube-scheduler\scheduler.go

首先构建SchedulerCommand对象

command := app.NewSchedulerCommand()

接下来执行runCommand

runCommand(cmd, args, opts)

根据配置信息启动Scheduler

Run(cc, stopCh)

构建scheduler对象

// Create the scheduler.
	sched, err := scheduler.New(cc.Client,
		cc.InformerFactory.Core().V1().Nodes(),
		cc.PodInformer,
		cc.InformerFactory.Core().V1().PersistentVolumes(),
		cc.InformerFactory.Core().V1().PersistentVolumeClaims(),
		cc.InformerFactory.Core().V1().ReplicationControllers(),
		cc.InformerFactory.Apps().V1().ReplicaSets(),
		cc.InformerFactory.Apps().V1().StatefulSets(),
		cc.InformerFactory.Core().V1().Services(),
		cc.InformerFactory.Policy().V1beta1().PodDisruptionBudgets(),
		storageClassInformer,
		cc.Recorder,
		cc.ComponentConfig.AlgorithmSource,
		stopCh,
		scheduler.WithName(cc.ComponentConfig.SchedulerName),
		scheduler.WithHardPodAffinitySymmetricWeight(cc.ComponentConfig.HardPodAffinitySymmetricWeight),
		scheduler.WithEquivalenceClassCacheEnabled(cc.ComponentConfig.EnableContentionProfiling),
		scheduler.WithPreemptionDisabled(cc.ComponentConfig.DisablePreemption),
		scheduler.WithPercentageOfNodesToScore(cc.ComponentConfig.PercentageOfNodesToScore),
		scheduler.WithBindTimeoutSeconds(*cc.ComponentConfig.BindTimeoutSeconds))

执行run方法

// Prepare a reusable runCommand function.
	run := func(ctx context.Context) {
		sched.Run()
		<-ctx.Done()
	}

接下来就是Scheduler的启动函数

func (sched *Scheduler) Run() {
	if !sched.config.WaitForCacheSync() {
		return
	}
	go wait.Until(sched.scheduleOne, 0, sched.config.StopEverything)
}

研究一下Run(cc, stopCh)中配置参数cc的由来：

func runCommand(cmd *cobra.Command, args []string, opts *options.Options) error

由Command对象以及命令行参数构建Config对象

c, err := opts.Config()

// Config return a scheduler config object
func (o *Options) Config() (*schedulerappconfig.Config, error) {
	if o.SecureServing != nil {
		if err := o.SecureServing.MaybeDefaultWithSelfSignedCerts("localhost", nil, []net.IP{net.ParseIP("127.0.0.1")}); err != nil {
			return nil, fmt.Errorf("error creating self-signed certificates: %v", err)
		}
	}

	c := &schedulerappconfig.Config{}
	if err := o.ApplyTo(c); err != nil {
		return nil, err
	}

	// Prepare kube clients.
	client, leaderElectionClient, eventClient, err := createClients(c.ComponentConfig.ClientConnection, o.Master, c.ComponentConfig.LeaderElection.RenewDeadline.Duration)
	if err != nil {
		return nil, err
	}

	// Prepare event clients.
	eventBroadcaster := record.NewBroadcaster()
	recorder := eventBroadcaster.NewRecorder(legacyscheme.Scheme, corev1.EventSource{Component: c.ComponentConfig.SchedulerName})

	// Set up leader election if enabled.
	var leaderElectionConfig *leaderelection.LeaderElectionConfig
	if c.ComponentConfig.LeaderElection.LeaderElect {
		leaderElectionConfig, err = makeLeaderElectionConfig(c.ComponentConfig.LeaderElection, leaderElectionClient, recorder)
		if err != nil {
			return nil, err
		}
	}

	c.Client = client
	c.InformerFactory = informers.NewSharedInformerFactory(client, 0)
	c.PodInformer = factory.NewPodInformer(client, 0)
	c.EventClient = eventClient
	c.Recorder = recorder
	c.Broadcaster = eventBroadcaster
	c.LeaderElection = leaderElectionConfig

	return c, nil
}

cc := c.Complete()

// Complete fills in any fields not set that are required to have valid data. It's mutating the receiver.
func (c *Config) Complete() CompletedConfig {
	cc := completedConfig{c}

	if c.InsecureServing != nil {
		c.InsecureServing.Name = "healthz"
	}
	if c.InsecureMetricsServing != nil {
		c.InsecureMetricsServing.Name = "metrics"
	}

	apiserver.AuthorizeClientBearerToken(c.LoopbackClientConfig, &c.Authentication, &c.Authorization)

	return CompletedConfig{&cc}
}

algorithmprovider.ApplyFeatureGates()

Run(cc, stopCh)

Config对象 

Scheduler上下文配置

// Config has all the context to run a Scheduler
type Config struct {
	// config is the scheduler server's configuration object.
	ComponentConfig kubeschedulerconfig.KubeSchedulerConfiguration

	// LoopbackClientConfig is a config for a privileged loopback connection
	LoopbackClientConfig *restclient.Config

	InsecureServing        *apiserver.DeprecatedInsecureServingInfo // nil will disable serving on an insecure port
	InsecureMetricsServing *apiserver.DeprecatedInsecureServingInfo // non-nil if metrics should be served independently
	Authentication         apiserver.AuthenticationInfo
	Authorization          apiserver.AuthorizationInfo
	SecureServing          *apiserver.SecureServingInfo

	Client          clientset.Interface
	InformerFactory informers.SharedInformerFactory
	PodInformer     coreinformers.PodInformer
	EventClient     v1core.EventsGetter
	Recorder        record.EventRecorder
	Broadcaster     record.EventBroadcaster

	// LeaderElection is optional.
	LeaderElection *leaderelection.LeaderElectionConfig
}

scheduler server配置信息

// KubeSchedulerConfiguration configures a scheduler
type KubeSchedulerConfiguration struct {
	metav1.TypeMeta

	// SchedulerName is name of the scheduler, used to select which pods
	// will be processed by this scheduler, based on pod's "spec.SchedulerName".
	SchedulerName string
	// AlgorithmSource specifies the scheduler algorithm source.
	AlgorithmSource SchedulerAlgorithmSource
	// RequiredDuringScheduling affinity is not symmetric, but there is an implicit PreferredDuringScheduling affinity rule
	// corresponding to every RequiredDuringScheduling affinity rule.
	// HardPodAffinitySymmetricWeight represents the weight of implicit PreferredDuringScheduling affinity rule, in the range 0-100.
	HardPodAffinitySymmetricWeight int32

	// LeaderElection defines the configuration of leader election client.
	LeaderElection KubeSchedulerLeaderElectionConfiguration

	// ClientConnection specifies the kubeconfig file and client connection
	// settings for the proxy server to use when communicating with the apiserver.
	ClientConnection apimachineryconfig.ClientConnectionConfiguration
	// HealthzBindAddress is the IP address and port for the health check server to serve on,
	// defaulting to 0.0.0.0:10251
	HealthzBindAddress string
	// MetricsBindAddress is the IP address and port for the metrics server to
	// serve on, defaulting to 0.0.0.0:10251.
	MetricsBindAddress string

	// DebuggingConfiguration holds configuration for Debugging related features
	// TODO: We might wanna make this a substruct like Debugging apiserverconfig.DebuggingConfiguration
	apiserverconfig.DebuggingConfiguration

	// DisablePreemption disables the pod preemption feature.
	DisablePreemption bool

	// PercentageOfNodeToScore is the percentage of all nodes that once found feasible
	// for running a pod, the scheduler stops its search for more feasible nodes in
	// the cluster. This helps improve scheduler's performance. Scheduler always tries to find
	// at least "minFeasibleNodesToFind" feasible nodes no matter what the value of this flag is.
	// Example: if the cluster size is 500 nodes and the value of this flag is 30,
	// then scheduler stops finding further feasible nodes once it finds 150 feasible ones.
	// When the value is 0, default percentage (50%) of the nodes will be scored.
	PercentageOfNodesToScore int32

	// DEPRECATED.
	// Indicate the "all topologies" set for empty topologyKey when it's used for PreferredDuringScheduling pod anti-affinity.
	FailureDomains string

	// Duration to wait for a binding operation to complete before timing out
	// Value must be non-negative integer. The value zero indicates no waiting.
	// If this value is nil, the default value will be used.
	BindTimeoutSeconds *int64
}

默认算法的设定过程：kubernetes\pkg\scheduler\apis\config\v1alpha1\register.go

func init() {
	// We only register manually written functions here. The registration of the
	// generated functions takes place in the generated files. The separation
	// makes the code compile even when the generated files are missing.
		localSchemeBuilder.Register(addDefaultingFuncs)
}

func addDefaultingFuncs(scheme *runtime.Scheme) error {
	return RegisterDefaults(scheme)
}

func RegisterDefaults(scheme *runtime.Scheme) error {
	scheme.AddTypeDefaultingFunc(&v1alpha1.KubeSchedulerConfiguration{}, func(obj interface{}) {
		SetObjectDefaults_KubeSchedulerConfiguration(obj.(*v1alpha1.KubeSchedulerConfiguration))
	})
	return nil
}

func SetObjectDefaults_KubeSchedulerConfiguration(in *v1alpha1.KubeSchedulerConfiguration) {
	SetDefaults_KubeSchedulerConfiguration(in)
}

// SetDefaults_KubeSchedulerConfiguration sets additional defaults
func SetDefaults_KubeSchedulerConfiguration(obj *kubescedulerconfigv1alpha1.KubeSchedulerConfiguration) {
	if len(obj.SchedulerName) == 0 {
		obj.SchedulerName = api.DefaultSchedulerName
	}

	if obj.HardPodAffinitySymmetricWeight == 0 {
		obj.HardPodAffinitySymmetricWeight = api.DefaultHardPodAffinitySymmetricWeight
	}

	if obj.AlgorithmSource.Policy == nil &&
		(obj.AlgorithmSource.Provider == nil || len(*obj.AlgorithmSource.Provider) == 0) {
		val := kubescedulerconfigv1alpha1.SchedulerDefaultProviderName
		obj.AlgorithmSource.Provider = &val
	}

	if policy := obj.AlgorithmSource.Policy; policy != nil {
		if policy.ConfigMap != nil && len(policy.ConfigMap.Namespace) == 0 {
			obj.AlgorithmSource.Policy.ConfigMap.Namespace = api.NamespaceSystem
		}
	}

	if host, port, err := net.SplitHostPort(obj.HealthzBindAddress); err == nil {
		if len(host) == 0 {
			host = "0.0.0.0"
		}
		obj.HealthzBindAddress = net.JoinHostPort(host, port)
	} else {
		obj.HealthzBindAddress = net.JoinHostPort("0.0.0.0", strconv.Itoa(ports.InsecureSchedulerPort))
	}

	if host, port, err := net.SplitHostPort(obj.MetricsBindAddress); err == nil {
		if len(host) == 0 {
			host = "0.0.0.0"
		}
		obj.MetricsBindAddress = net.JoinHostPort(host, port)
	} else {
		obj.MetricsBindAddress = net.JoinHostPort("0.0.0.0", strconv.Itoa(ports.InsecureSchedulerPort))
	}

	if len(obj.LeaderElection.LockObjectNamespace) == 0 {
		obj.LeaderElection.LockObjectNamespace = kubescedulerconfigv1alpha1.SchedulerDefaultLockObjectNamespace
	}
	if len(obj.LeaderElection.LockObjectName) == 0 {
		obj.LeaderElection.LockObjectName = kubescedulerconfigv1alpha1.SchedulerDefaultLockObjectName
	}

	if obj.PercentageOfNodesToScore == 0 {
		// by default, stop finding feasible nodes once the number of feasible nodes is 50% of the cluster.
		obj.PercentageOfNodesToScore = 50
	}

	if len(obj.FailureDomains) == 0 {
		obj.FailureDomains = kubeletapis.DefaultFailureDomains
	}

	if len(obj.ClientConnection.ContentType) == 0 {
		obj.ClientConnection.ContentType = "application/vnd.kubernetes.protobuf"
	}
	// Scheduler has an opinion about QPS/Burst, setting specific defaults for itself, instead of generic settings.
	if obj.ClientConnection.QPS == 0.0 {
		obj.ClientConnection.QPS = 50.0
	}
	if obj.ClientConnection.Burst == 0 {
		obj.ClientConnection.Burst = 100
	}

	// Use the default LeaderElectionConfiguration options
	apiserverconfigv1alpha1.RecommendedDefaultLeaderElectionConfiguration(&obj.LeaderElection.LeaderElectionConfiguration)

	if obj.BindTimeoutSeconds == nil {
		defaultBindTimeoutSeconds := int64(600)
		obj.BindTimeoutSeconds = &defaultBindTimeoutSeconds
	}
}

可知默认调度算法是由register.go初始化完成的。

调度器名字

if len(obj.SchedulerName) == 0 {
		obj.SchedulerName = api.DefaultSchedulerName
	}

const (
	// "default-scheduler" is the name of default scheduler.
	DefaultSchedulerName = "default-scheduler"

	// RequiredDuringScheduling affinity is not symmetric, but there is an implicit PreferredDuringScheduling affinity rule
	// corresponding to every RequiredDuringScheduling affinity rule.
	// When the --hard-pod-affinity-weight scheduler flag is not specified,
	// DefaultHardPodAffinityWeight defines the weight of the implicit PreferredDuringScheduling affinity rule.
	DefaultHardPodAffinitySymmetricWeight int32 = 1
)

Provider提供者

if obj.AlgorithmSource.Policy == nil &&
		(obj.AlgorithmSource.Provider == nil || len(*obj.AlgorithmSource.Provider) == 0) {
		val := kubescedulerconfigv1alpha1.SchedulerDefaultProviderName
		obj.AlgorithmSource.Provider = &val
	}

const (
	// SchedulerDefaultLockObjectNamespace defines default scheduler lock object namespace ("kube-system")
    SchedulerDefaultLockObjectNamespace string = metav1.NamespaceSystem

	// SchedulerDefaultLockObjectName defines default scheduler lock object name ("kube-scheduler")
	SchedulerDefaultLockObjectName = "kube-scheduler"

	// SchedulerDefaultProviderName defines the default provider names
	SchedulerDefaultProviderName = "DefaultProvider"
)