k8s之kube-controller-manager 源码分析
Kubernetes 控制器管理器（kube-controller-manager）是一个守护进程，内嵌随 Kubernetes 一起发布的核心控制回路。 在机器人和自动化的应用中，控制回路是一个永不休止的循环，用于调节系统状态。 在 Kubernetes 中，每个控制器是一个控制回路，通过 API 服务器监视集群的共享状态， 并尝试进行更改以将当前状态转为期望状态。 目前，Kubernetes 自带的控制器例子包括副本控制器、节点控制器、命名空间控制器和服务账号控制器等。
本文不对 kube-controller-manager 管理的每个控制器的执行原理做介绍，只是从全局观看一下kube-controller-manager 启动每个控制器的整体实现过程。
k8s: v1.27.3
文件： cmd/kube-controller-manager/app/controllermanager.go
控制器选项初始化
// cmd/kube-controller-manager/app/controllermanager.go#L104
func NewControllerManagerCommand() *cobra.Command {
// 所有内置控制器配置
s, err := options.NewKubeControllerManagerOptions()
}
调用 options.NewKubeControllerManagerOptions() 对所有内置控制器及全局配置进行初始化。
func NewKubeControllerManagerOptions() (*KubeControllerManagerOptions, error) {
componentConfig, err := NewDefaultComponentConfig()
if err != nil {
return nil, err
}
s := KubeControllerManagerOptions{
Generic: cmoptions.NewGenericControllerManagerConfigurationOptions(&componentConfig.Generic),
KubeCloudShared: cpoptions.NewKubeCloudSharedOptions(&componentConfig.KubeCloudShared),
ServiceController: &cpoptions.ServiceControllerOptions{
ServiceControllerConfiguration: &componentConfig.ServiceController,
},
AttachDetachController: &AttachDetachControllerOptions{
&componentConfig.AttachDetachController,
},
CSRSigningController: &CSRSigningControllerOptions{
&componentConfig.CSRSigningController,
},
DaemonSetController: &DaemonSetControllerOptions{
&componentConfig.DaemonSetController,
},
DeploymentController: &DeploymentControllerOptions{
&componentConfig.DeploymentController,
},
StatefulSetController: &StatefulSetControllerOptions{
&componentConfig.StatefulSetController,
},
DeprecatedFlags: &DeprecatedControllerOptions{
&componentConfig.DeprecatedController,
},
EndpointController: &EndpointControllerOptions{
&componentConfig.EndpointController,
},
EndpointSliceController: &EndpointSliceControllerOptions{
&componentConfig.EndpointSliceController,
},
EndpointSliceMirroringController: &EndpointSliceMirroringControllerOptions{
&componentConfig.EndpointSliceMirroringController,
},
EphemeralVolumeController: &EphemeralVolumeControllerOptions{
&componentConfig.EphemeralVolumeController,
},
GarbageCollectorController: &GarbageCollectorControllerOptions{
&componentConfig.GarbageCollectorController,
},
HPAController: &HPAControllerOptions{
&componentConfig.HPAController,
},
JobController: &JobControllerOptions{
&componentConfig.JobController,
},
CronJobController: &CronJobControllerOptions{
&componentConfig.CronJobController,
},
NamespaceController: &NamespaceControllerOptions{
&componentConfig.NamespaceController,
},
NodeIPAMController: &NodeIPAMControllerOptions{
&componentConfig.NodeIPAMController,
},
NodeLifecycleController: &NodeLifecycleControllerOptions{
&componentConfig.NodeLifecycleController,
},
PersistentVolumeBinderController: &PersistentVolumeBinderControllerOptions{
&componentConfig.PersistentVolumeBinderController,
},
PodGCController: &PodGCControllerOptions{
&componentConfig.PodGCController,
},
ReplicaSetController: &ReplicaSetControllerOptions{
&componentConfig.ReplicaSetController,
},
ReplicationController: &ReplicationControllerOptions{
&componentConfig.ReplicationController,
},
ResourceQuotaController: &ResourceQuotaControllerOptions{
&componentConfig.ResourceQuotaController,
},
SAController: &SAControllerOptions{
&componentConfig.SAController,
},
TTLAfterFinishedController: &TTLAfterFinishedControllerOptions{
&componentConfig.TTLAfterFinishedController,
},
SecureServing: apiserveroptions.NewSecureServingOptions().WithLoopback(),
Authentication: apiserveroptions.NewDelegatingAuthenticationOptions(),
Authorization: apiserveroptions.NewDelegatingAuthorizationOptions(),
Metrics: metrics.NewOptions(),
Logs: logs.NewOptions(),
}
s.Authentication.RemoteKubeConfigFileOptional = true
s.Authorization.RemoteKubeConfigFileOptional = true
// Set the PairName but leave certificate directory blank to generate in-memory by default
s.SecureServing.ServerCert.CertDirectory = ""
s.SecureServing.ServerCert.PairName = "kube-controller-manager"
s.SecureServing.BindPort = ports.KubeControllerManagerPort
gcIgnoredResources := make([]garbagecollectorconfig.GroupResource, 0, len(garbagecollector.DefaultIgnoredResources()))
for r := range garbagecollector.DefaultIgnoredResources() {
gcIgnoredResources = append(gcIgnoredResources, garbagecollectorconfig.GroupResource{Group: r.Group, Resource: r.Resource})
}
s.GarbageCollectorController.GCIgnoredResources = gcIgnoredResources
s.Generic.LeaderElection.ResourceName = "kube-controller-manager"
s.Generic.LeaderElection.ResourceNamespace = "kube-system"
return &s, nil
}
这里的许多控制器都做并发数据控制，如 DeploymentController 、DaemonSetController 和 EndpointController 等。
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