golang-net

创建pod的流程

新建pod的流程，当一个pod完成调用，需要与一个node绑定，然后pod触发kubelet在循环控制里注册的handler，通过检查pod在kubelet内存中的状态，判断是否为新调度的pod，从而触发add。然后kubelet为这个pod生成对应的podStatus，包括检查volume，然后调用容器。

func (kl *Kubelet) HandlePodAdditions(pods []*v1.Pod) {
    start := kl.clock.Now()
    //日期排序
    sort.Sort(sliceutils.PodsByCreationTime(pods))
    for _, pod := range pods {
        existingPods := kl.podManager.GetPods()
        // Always add the pod to the pod manager. Kubelet relies on the pod
        // manager as the source of truth for the desired state. If a pod does
        // not exist in the pod manager, it means that it has been deleted in
        // the apiserver and no action (other than cleanup) is required.
        kl.podManager.AddPod(pod)

        if kubetypes.IsMirrorPod(pod) {
            kl.handleMirrorPod(pod, start)
            continue
        }

        // Only go through the admission process if the pod is not requested
        // for termination by another part of the kubelet. If the pod is already
        // using resources (previously admitted), the pod worker is going to be
        // shutting it down. If the pod hasn't started yet, we know that when
        // the pod worker is invoked it will also avoid setting up the pod, so
        // we simply avoid doing any work.
        if !kl.podWorkers.IsPodTerminationRequested(pod.UID) {
            // We failed pods that we rejected, so activePods include all admitted
            // pods that are alive.
            activePods := kl.filterOutInactivePods(existingPods)

            // Check if we can admit the pod; if not, reject it.
            //看是否能在计算机上创建 资源是否足够
            if ok, reason, message := kl.canAdmitPod(activePods, pod); !ok {
                kl.rejectPod(pod, reason, message)
                continue
            }
        }
        mirrorPod, _ := kl.podManager.GetMirrorPodByPod(pod)
        //调用dispatchWork 转而调用update
        kl.dispatchWork(pod, kubetypes.SyncPodCreate, mirrorPod, start)
    }
}

在1.23版本，将定期检查变到
func (kl *Kubelet) syncPod(ctx context.Context, updateType kubetypes.SyncPodType, pod, mirrorPod *v1.Pod, podStatus *kubecontainer.PodStatus) (isTerminal bool, err error)
同时在这个函数里面有对容器的创建，判断网络模式等

最终的启动容器在startContainer
1.拉取镜像 涉及到怎么拉区 从本地 还是远程
2.创建container 容器的配置信息等 
3.启动
-- 启动完涉及到日志管理，如果采用了cni则需要修改日志路径 若该版本本身具有cni 就需要移除日志的符号链接
4.做一些预处理 比如生命周期，容器name，容器id设置

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