文档章节

从源码看kubernetes与CNI Plugin的集成

WaltonWang
 WaltonWang
发布于 2017/05/23 23:04
字数 1258
阅读 593
收藏 5

更多关于kubernetes的深入文章,请看我csdn或者oschina的博客主页。

libcni

cni项目提供了golang写的一个library,定义了集成cni插件的应用需调用的cni plugin接口,它就是libcni。其对应的Interface定义如下:

libcni/api.go:51

type CNI interface {
	AddNetworkList(net *NetworkConfigList, rt *RuntimeConf) (types.Result, error)
	DelNetworkList(net *NetworkConfigList, rt *RuntimeConf) error

	AddNetwork(net *NetworkConfig, rt *RuntimeConf) (types.Result, error)
	DelNetwork(net *NetworkConfig, rt *RuntimeConf) error
}

CNI Plugin在kubelet管理的PLEG中何时被调用

kubelet Run方法方法中会最终调用syncLoopIteration函数,由它通过各种channel对pod进行sync。

pkg/kubelet/kubelet.go:1794
    
// syncLoopIteration reads from various channels and dispatches pods to the
// given handler.
//
// Arguments:
// 1.  configCh:       a channel to read config events from
// 2.  handler:        the SyncHandler to dispatch pods to
// 3.  syncCh:         a channel to read periodic sync events from
// 4.  houseKeepingCh: a channel to read housekeeping events from
// 5.  plegCh:         a channel to read PLEG updates from
//
// Events are also read from the kubelet liveness manager's update channel.
//
// The workflow is to read from one of the channels, handle that event, and
// update the timestamp in the sync loop monitor.
//
// Here is an appropriate place to note that despite the syntactical
// similarity to the switch statement, the case statements in a select are
// evaluated in a pseudorandom order if there are multiple channels ready to
// read from when the select is evaluated.  In other words, case statements
// are evaluated in random order, and you can not assume that the case
// statements evaluate in order if multiple channels have events.
//
// With that in mind, in truly no particular order, the different channels
// are handled as follows:
//
// * configCh: dispatch the pods for the config change to the appropriate
//             handler callback for the event type
// * plegCh: update the runtime cache; sync pod
// * syncCh: sync all pods waiting for sync
// * houseKeepingCh: trigger cleanup of pods
// * liveness manager: sync pods that have failed or in which one or more
//                     containers have failed liveness checks
func (kl *Kubelet) syncLoopIteration(configCh <-chan kubetypes.PodUpdate, handler SyncHandler,
	syncCh <-chan time.Time, housekeepingCh <-chan time.Time, plegCh <-chan *pleg.PodLifecycleEvent) bool {
	kl.syncLoopMonitor.Store(kl.clock.Now())
	select {
	case u, open := <-configCh:
		// Update from a config source; dispatch it to the right handler
		// callback.
		if !open {
			glog.Errorf("Update channel is closed. Exiting the sync loop.")
			return false
		}
    
		switch u.Op {
		case kubetypes.ADD:
			glog.V(2).Infof("SyncLoop (ADD, %q): %q", u.Source, format.Pods(u.Pods))
			// After restarting, kubelet will get all existing pods through
			// ADD as if they are new pods. These pods will then go through the
			// admission process and *may* be rejected. This can be resolved
			// once we have checkpointing.
			handler.HandlePodAdditions(u.Pods)
		case kubetypes.UPDATE:
			glog.V(2).Infof("SyncLoop (UPDATE, %q): %q", u.Source, format.PodsWithDeletiontimestamps(u.Pods))
			handler.HandlePodUpdates(u.Pods)
		case kubetypes.REMOVE:
			glog.V(2).Infof("SyncLoop (REMOVE, %q): %q", u.Source, format.Pods(u.Pods))
			handler.HandlePodRemoves(u.Pods)
		case kubetypes.RECONCILE:
			glog.V(4).Infof("SyncLoop (RECONCILE, %q): %q", u.Source, format.Pods(u.Pods))
			handler.HandlePodReconcile(u.Pods)
		case kubetypes.DELETE:
			glog.V(2).Infof("SyncLoop (DELETE, %q): %q", u.Source, format.Pods(u.Pods))
			// DELETE is treated as a UPDATE because of graceful deletion.
			handler.HandlePodUpdates(u.Pods)
		case kubetypes.SET:
			// TODO: Do we want to support this?
			glog.Errorf("Kubelet does not support snapshot update")
		}
    
		// Mark the source ready after receiving at least one update from the
		// source. Once all the sources are marked ready, various cleanup
		// routines will start reclaiming resources. It is important that this
		// takes place only after kubelet calls the update handler to process
		// the update to ensure the internal pod cache is up-to-date.
		kl.sourcesReady.AddSource(u.Source)
	case e := <-plegCh:
		if isSyncPodWorthy(e) {
			// PLEG event for a pod; sync it.
			if pod, ok := kl.podManager.GetPodByUID(e.ID); ok {
				glog.V(2).Infof("SyncLoop (PLEG): %q, event: %#v", format.Pod(pod), e)
				handler.HandlePodSyncs([]*v1.Pod{pod})
			} else {
				// If the pod no longer exists, ignore the event.
				glog.V(4).Infof("SyncLoop (PLEG): ignore irrelevant event: %#v", e)
			}
		}
    
		if e.Type == pleg.ContainerDied {
			if containerID, ok := e.Data.(string); ok {
				kl.cleanUpContainersInPod(e.ID, containerID)
			}
		}
	case <-syncCh:
		// Sync pods waiting for sync
		podsToSync := kl.getPodsToSync()
		if len(podsToSync) == 0 {
			break
		}
		glog.V(4).Infof("SyncLoop (SYNC): %d pods; %s", len(podsToSync), format.Pods(podsToSync))
		kl.HandlePodSyncs(podsToSync)
	case update := <-kl.livenessManager.Updates():
		if update.Result == proberesults.Failure {
			// The liveness manager detected a failure; sync the pod.
    
			// We should not use the pod from livenessManager, because it is never updated after
			// initialization.
			pod, ok := kl.podManager.GetPodByUID(update.PodUID)
			if !ok {
				// If the pod no longer exists, ignore the update.
				glog.V(4).Infof("SyncLoop (container unhealthy): ignore irrelevant update: %#v", update)
				break
			}
			glog.V(1).Infof("SyncLoop (container unhealthy): %q", format.Pod(pod))
			handler.HandlePodSyncs([]*v1.Pod{pod})
		}
	case <-housekeepingCh:
		if !kl.sourcesReady.AllReady() {
			// If the sources aren't ready or volume manager has not yet synced the states,
			// skip housekeeping, as we may accidentally delete pods from unready sources.
			glog.V(4).Infof("SyncLoop (housekeeping, skipped): sources aren't ready yet.")
		} else {
			glog.V(4).Infof("SyncLoop (housekeeping)")
			if err := handler.HandlePodCleanups(); err != nil {
				glog.Errorf("Failed cleaning pods: %v", err)
			}
		}
	}
	kl.syncLoopMonitor.Store(kl.clock.Now())
	return true
}
    

说明:

  • HandlePodSyncs, HandlePodUpdates, HandlePodAdditions最终都是invoke dispatchWork来分发pods到podWorker进行异步的pod sync。
  • HandlePodRemoves调用一下接口,将pod从cache中删除,kill pod中进程,并 stop Pod的Probe Workers,最终通过捕获Pod的PLEG Event,通过cleanUpContainersInPod来清理Pod。 pkg/kubelet/kubelet.go:1994 kl.podManager.DeletePod(pod); kl.deletePod(pod); kl.probeManager.RemovePod(pod);
  • HandlePodReconcile中,如果Pod是通过Eviction导致的Failed,则调用kl.containerDeletor.deleteContainersInPod来清除Pod内的容器。

HandlePodSyncs, HandlePodUpdates, HandlePodAdditions

  • Kubelet.dispatchWork最终会invoke podWokers.managePodLoop,podWorkers会嗲用NewMainKubelet时给PodWorkers注册的syncPodFn= (kl *Kubelet) syncPod(o syncPodOptions)。
  • Kubelet.syncPod会根据runtime类型进行区分,我们只看runtime为docker的情况,会invoke DockerManager.SyncPod。
  • DockerManager.SyncPod会dm.network.SetUpPod,然后根据network plugin类型进行区分,我们只看cni plugin,会对应invoke cniNetworkPlugin.SetUpPod进行网络设置。
  • cniNetworkPlugin.SetUpPod invoke cniNetwork.addToNetwork,由后者最终调用CNIConfig.AddNetwork,这就是libcni中对应的AddNetwork Interface。
  • CNIConfig.AddNetwork通过封装好的execPlugin由系统去调用cni plugin bin,到此就完成了pod内的网络设置。

HandlePodRemoves, HandlePodReconcile

  • 都是通过invoke podContainerDeleter.deleteContainerInPod来清理容器。
  • 对于docker,deleteContainerInPod会调用DockerManager.delteContainer。
  • 在deleteContainer时,通过invoke containerGC.netContainerCleanup进行容器的网络环境清理。
  • 然后由PluginManger.TearDownPod去调用cniNetworkPlugin.TearDownPod,再执行cniNetwork.deleteFromNetwork。
  • cniNetwork.deleteFromNetwork会调用CNIConfig.DelNetwork,这就是libcni中对应的DelNetwork Interface。
  • CNIConfig.AddNetwork通过封装好的execPlugin由系统去调用cni plugin bin,到此就完成了pod内的网络清理。

kubelet中与cni plugin调用的代码流程图

输入图片说明

更多关于kubernetes的深入文章,请看我csdn或者oschina的博客主页。

© 著作权归作者所有

共有 人打赏支持
WaltonWang
粉丝 196
博文 100
码字总数 207940
作品 0
深圳
程序员
私信 提问
加载中

评论(1)

隐形者
隐形者
orz是yyyy
3 天烧脑式容器存储网络训练营 | 深圳站

容器进入云计算AI时代,大规模容器集群即将进入千万家企业,业务特征十分复杂,如:容器数量庞大,需要满足快速部署灵活迁移,保证容器间跨物理机间的通信;保证业务、资源与物理位置无关,容...

DockOne
2017/07/06
291
0
kubernetes 1.8 高可用安装(四)

4、安装kubernetes node Kubernetes的一个Node节点上需要运行如下组件: Docker,目前安装的是docker-1.12.6 kubelet kube-proxy 使用daemonset安装 4.1 安装kubelet和cni 安装rpm包 yum lo...

战狐
2017/11/01
0
0
苏宁容器云基于Kubernetes和Contiv的网络架构技术实现

容器云的发展和落地,使得越来越多的无状态服务迁移到容器云,加快容器云的落地。容器云的发展,使得更大限度的利用计算资源,这相对传统虚拟化技术来说,就有了很多优势,例如支持高可用时无...

Docker
07/02
0
0
Kubernetes 1.5.1 发布,容器集群管理系统

Kubernetes 1.5.1 发布了,Kubernetes 是来自 Google 云平台的开源容器集群管理系统。基于 Docker 构建一个容器的调度服务。该系统可以自动在一个容器集群中选择一个工作容器供使用。 更新内...

达尔文
2016/12/18
1K
4
kubernetes安装问题记录

一、pod-infrastructure:latest镜像下载失败 报错一:image pull failed for registry.access.redhat.com/rhel7/pod-infrastructure:latest, this may be because there are no credentials ......

TsingCall
06/26
0
0

没有更多内容

加载失败,请刷新页面

加载更多

十万个为什么之为什么大家都说dubbo

Dubbo是什么? 使用背景 dubbo为什么这么流行, 为什么大家都这么喜欢用dubbo; 通过了解分布式开发了解到, 为适应访问量暴增,业务拆分后, 子应用部署在多台服务器上,而多台服务器通过可以通过d...

尾生
39分钟前
2
0
Docker搭建代码质量检测平台-SonarQube(中文版)

Sonar是一个用于代码质量管理的开源平台,用于管理源代码的质量,可以从七个维度检测代码质量。通过插件形式,可以支持包括java,C#,C/C++,PL/SQL,Cobol,JavaScrip,Groovy等等二十几种编程语言...

Jacktanger
45分钟前
2
0
Windows / Linux / MacOS 设置代理上网的方法汇总

本文汇总了 Windows / Linux / MacOS 设置代理上网的各种方法,总结如下: 1、设置系统代理(Windows、Linux、MacOS) 2、设置代理插件(Chrome、Chromium、Firefox、Opera、QQ等浏览器) 3、...

sunboy2050
昨天
4
0
自定义 Maven 的 repositories

有时,应用中需要一些比较新的依赖,而这些依赖并没有正式发布,还是处于milestone或者是snapshot阶段,并不能从中央仓库或者镜像站上下载到。此时,就需要 自定义Maven的<repositories>。 ...

waylau
昨天
3
0
徒手写一个es6代码库

mkdir democd demonpm initnpm install -g babelnpm install -g babel-clinpm install --save-dev babel-preset-es2015-node5 在项目目录创建两个文件夹 functional-playground ......

lilugirl
昨天
4
0

没有更多内容

加载失败,请刷新页面

加载更多

返回顶部
顶部