k8s源码走读-----replicasSetcontroller

一、介绍

replicasSet作用 主要负责使pod的个数保持期望的状态。
版本：1.19

二、流程

1、启动

所有的controller的启动逻辑基本都一样。kubecontroller-manage组件启动时，会统一启动所有的controller。

func NewControllerInitializers(loopMode ControllerLoopMode) map[string]InitFunc {
.....
	controllers["replicationcontroller"] = startReplicationController
.....
	return controllers
}

startReplicationController会启动replicasSetcontroller，定时同步数据。可以看到rscontroller监听了pod 和 rs两种资源。当这两种资源变化时，会走到rs controller中。

BurstReplicas： 每次最多处理的pod个数，默认为500
ConcurrentRCSyncs：每次启动的处理协程数，默认为5

func startReplicationController(ctx ControllerContext) (http.Handler, bool, error) {
	go replicationcontroller.NewReplicationManager(
		ctx.InformerFactory.Core().V1().Pods(),
		ctx.InformerFactory.Core().V1().ReplicationControllers(),
		ctx.ClientBuilder.ClientOrDie("replication-controller"),
		replicationcontroller.BurstReplicas,
	).Run(int(ctx.ComponentConfig.ReplicationController.ConcurrentRCSyncs), ctx.Stop)
	return nil, true, nil
}

3、然后就看NewReplicationManager方法的逻辑。主要就是配置event,然后，NewBaseController方法中初始化各种回调函数等。

func NewReplicationManager(podInformer coreinformers.PodInformer, rcInformer coreinformers.ReplicationControllerInformer, kubeClient clientset.Interface, burstReplicas int) *ReplicationManager {
	eventBroadcaster := record.NewBroadcaster()
	eventBroadcaster.StartStructuredLogging(0)
	eventBroadcaster.StartRecordingToSink(&v1core.EventSinkImpl{Interface: kubeClient.CoreV1().Events("")})
	return &ReplicationManager{
		*replicaset.NewBaseController(informerAdapter{rcInformer}, podInformer, clientsetAdapter{kubeClient}, burstReplicas,
			v1.SchemeGroupVersion.WithKind("ReplicationController"),
			"replication_controller",
			"replicationmanager",
			podControlAdapter{controller.RealPodControl{
				KubeClient: kubeClient,
				Recorder:   eventBroadcaster.NewRecorder(scheme.Scheme, v1.EventSource{Component: "replication-controller"}),
			}},
		),
	}
}

4、NewBaseController中主要是配置inform的回调函数。初始化rscontroller,配置回调函数rsinform和podinform、和同步函数。
注意一下expectations: controller.NewUIDTrackingControllerExpectations(controller.NewControllerExpectations())

func NewBaseController(rsInformer appsinformers.ReplicaSetInformer, podInformer coreinformers.PodInformer, kubeClient clientset.Interface, burstReplicas int,
	gvk schema.GroupVersionKind, metricOwnerName, queueName string, podControl controller.PodControlInterface) *ReplicaSetController {
	if kubeClient != nil && kubeClient.CoreV1().RESTClient().GetRateLimiter() != nil {
		ratelimiter.RegisterMetricAndTrackRateLimiterUsage(metricOwnerName, kubeClient.CoreV1().RESTClient().GetRateLimiter())
	}
    //初始化一个rscontroller
	rsc := &ReplicaSetController{
		GroupVersionKind: gvk,     //group version kind 
		kubeClient:       kubeClient,
		podControl:       podControl,
		burstReplicas:    burstReplicas,
		expectations:     controller.NewUIDTrackingControllerExpectations(controller.NewControllerExpectations()),
		queue:            workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), queueName),
	}

	rsInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    rsc.addRS,
		UpdateFunc: rsc.updateRS,
		DeleteFunc: rsc.deleteRS,
	})
	rsc.rsLister = rsInformer.Lister()
	rsc.rsListerSynced = rsInformer.Informer().HasSynced

	podInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: rsc.addPod,
		// This invokes the ReplicaSet for every pod change, eg: host assignment. Though this might seem like
		// overkill the most frequent pod update is status, and the associated ReplicaSet will only list from
		// local storage, so it should be ok.
		UpdateFunc: rsc.updatePod,
		DeleteFunc: rsc.deletePod,
	})
	rsc.podLister = podInformer.Lister()
	rsc.podListerSynced = podInformer.Informer().HasSynced

	rsc.syncHandler = rsc.syncReplicaSet

	return rsc
}

//各个handler

//rs

//增加 则 入队
func (rsc *ReplicaSetController) addRS(obj interface{}) {
	rs := obj.(*apps.ReplicaSet)
	klog.V(4).Infof("Adding %s %s/%s", rsc.Kind, rs.Namespace, rs.Name)
	rsc.enqueueRS(rs)
}

//判断uid，不同，删除旧的，入队。
// callback when RS is updated
func (rsc *ReplicaSetController) updateRS(old, cur interface{}) {
	oldRS := old.(*apps.ReplicaSet)
	curRS := cur.(*apps.ReplicaSet)

	// TODO: make a KEP and fix informers to always call the delete event handler on re-create
	if curRS.UID != oldRS.UID {
		key, err := controller.KeyFunc(oldRS)
		if err != nil {
			utilruntime.HandleError(fmt.Errorf("couldn't get key for object %#v: %v", oldRS, err))
			return
		}
		rsc.deleteRS(cache.DeletedFinalStateUnknown{
			Key: key,
			Obj: oldRS,
		})
	}

	// You might imagine that we only really need to enqueue the
	// replica set when Spec changes, but it is safer to sync any
	// time this function is triggered. That way a full informer
	// resync can requeue any replica set that don't yet have pods
	// but whose last attempts at creating a pod have failed (since
	// we don't block on creation of pods) instead of those
	// replica sets stalling indefinitely. Enqueueing every time
	// does result in some spurious syncs (like when Status.Replica
	// is updated and the watch notification from it retrig