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<!DOCTYPE HTML>
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<title>kubelet statusManager 源码分析 · 田飞雨</title>
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<li class="chapter " data-level="1.1" data-path="../">
<a href="../">
<b>1.1.</b>
Introduction
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<li class="chapter " data-level="1.2" data-path="./">
<a href="./">
<b>1.2.</b>
kubernetes
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kube-apiserver 的设计与实现
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kube-apiserver 中 apiserver service 的实现
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<b>1.2.3.</b>
node controller 源码分析
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<b>1.2.4.</b>
job controller 源码分析
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<a href="garbagecollector_controller.html">
<b>1.2.5.</b>
garbage collector controller 源码分析
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<li class="chapter " data-level="1.2.6" data-path="daemonset_controller.html">
<a href="daemonset_controller.html">
<b>1.2.6.</b>
daemonset controller 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.7" data-path="statefulset_controller.html">
<a href="statefulset_controller.html">
<b>1.2.7.</b>
statefulset controller 源码分析
</a>
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<li class="chapter " data-level="1.2.8" data-path="deployment_controller.html">
<a href="deployment_controller.html">
<b>1.2.8.</b>
deployment controller 源码分析
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<li class="chapter " data-level="1.2.9" data-path="replicaset_controller.html">
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<b>1.2.9.</b>
replicaset controller 源码分析
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<b>1.2.10.</b>
kube-scheduler 源码分析
</a>
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<li class="chapter " data-level="1.2.11" data-path="kube_scheduler_algorithm.html">
<a href="kube_scheduler_algorithm.html">
<b>1.2.11.</b>
kube-scheduler predicates 与 priorities 调度算法源码分析
</a>
</li>
<li class="chapter " data-level="1.2.12" data-path="kube_scheduler_preempt.html">
<a href="kube_scheduler_preempt.html">
<b>1.2.12.</b>
kube-scheduler 优先级与抢占机制源码分析
</a>
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<li class="chapter " data-level="1.2.13" data-path="k8s_service_theory.html">
<a href="k8s_service_theory.html">
<b>1.2.13.</b>
kubernetes service 原理解析
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<li class="chapter " data-level="1.2.14" data-path="kube_proxy_process.html">
<a href="kube_proxy_process.html">
<b>1.2.14.</b>
kube-proxy 源码分析
</a>
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<li class="chapter " data-level="1.2.15" data-path="kube_proxy_iptables.html">
<a href="kube_proxy_iptables.html">
<b>1.2.15.</b>
kube-proxy iptables 模式源码分析
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<b>1.2.16.</b>
kube-proxy ipvs 模式源码分析
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<a href="kubelet-modules.html">
<b>1.2.17.</b>
kubelet 架构浅析
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<li class="chapter " data-level="1.2.18" data-path="kubelet_init.html">
<a href="kubelet_init.html">
<b>1.2.18.</b>
kubelet 启动流程分析
</a>
</li>
<li class="chapter " data-level="1.2.19" data-path="kubelet_create_pod.html">
<a href="kubelet_create_pod.html">
<b>1.2.19.</b>
kubelet 创建 pod 的流程
</a>
</li>
<li class="chapter " data-level="1.2.20" data-path="node_status.html">
<a href="node_status.html">
<b>1.2.20.</b>
kubelet 状态上报的方式
</a>
</li>
<li class="chapter " data-level="1.2.21" data-path="k8s_events.html">
<a href="k8s_events.html">
<b>1.2.21.</b>
kubelet 中事件处理机制
</a>
</li>
<li class="chapter active" data-level="1.2.22" data-path="kubelet_status_manager.html">
<a href="kubelet_status_manager.html">
<b>1.2.22.</b>
kubelet statusManager 源码分析
</a>
</li>
<li class="chapter " data-level="1.2.23" data-path="kubelet_qos.html">
<a href="kubelet_qos.html">
<b>1.2.23.</b>
kubernetes 中 Qos 的设计与实现
</a>
</li>
<li class="chapter " data-level="1.2.24" data-path="kubelet_garbage_collect.html">
<a href="kubelet_garbage_collect.html">
<b>1.2.24.</b>
kubelet 中垃圾回收机制的设计与实现
</a>
</li>
<li class="chapter " data-level="1.2.25" data-path="k8s_evicted.html">
<a href="k8s_evicted.html">
<b>1.2.25.</b>
kubernetes 中 Evicted pod 是如何产生的
</a>
</li>
<li class="chapter " data-level="1.2.26" data-path="kubernetes_descheduler.html">
<a href="kubernetes_descheduler.html">
<b>1.2.26.</b>
Kubernetes 中 Descheduler 组件的使用与扩展
</a>
</li>
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<li class="chapter " data-level="1.3" data-path="../knative/">
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<b>1.3.</b>
knative
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<a href="../knative/deploy_with_minkube.html">
<b>1.3.1.</b>
在 minkube 上部署 knative
</a>
</li>
<li class="chapter " data-level="1.3.2" data-path="../knative/knative_serving.html">
<a href="../knative/knative_serving.html">
<b>1.3.2.</b>
knative serving 组件分析
</a>
</li>
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<li class="chapter " data-level="1.4" data-path="../cgroup/">
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<b>1.4.</b>
cgroup
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<b>1.4.1.</b>
blkio cgroup
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<li class="chapter " data-level="1.4.2" data-path="../cgroup/pid_cgroup.html">
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<b>1.4.2.</b>
pid cgroup
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<li class="chapter " data-level="1.5" data-path="../go/">
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<b>1.5.</b>
go
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<a href="../go/func_return_value_or_pointer.html">
<b>1.5.1.</b>
golang 中函数使用值返回与指针返回的区别，底层原理分析
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</li>
<li class="chapter " data-level="1.5.2" data-path="../go/golang_bootstrap.html">
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<b>1.5.2.</b>
Golang 程序启动流程分析
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Golang GPM 模型剖析
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<li><a href="#statusmanager-源码分析">statusManager 源码分析</a><ul>
<li><a href="#statusmanager-的初始化">statusManager 的初始化</a></li>
<li><a href="#syncpod">syncPod</a><ul>
<li><a href="#needsupdate">needsUpdate</a><ul>
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</ul>
</li>
<li><a href="#setcontainerreadiness">SetContainerReadiness</a></li>
<li><a href="#setcontainerstartup">SetContainerStartup</a></li>
<li><a href="#terminatepod">TerminatePod</a></li>
<li><a href="#removeorphanedstatuses">RemoveOrphanedStatuses</a></li>
</ul>
</li>
<li><a href="#总结">总结</a></li>
</ul>
<p>本篇文章没有接上篇继续更新 kube-controller-manager，kube-controller-manager 的源码阅读笔记也会继续更新，笔者会同时阅读多个组件的源码，阅读笔记也会按组件进行交叉更新，交叉更新的目的一是为了加深印象避免阅读完后又很快忘记，二是某些代码的功能难以理解，避免死磕，但整体目标是将每个组件的核心代码阅读完。</p>
<p>在前面的文章中已经介绍过 kubelet 的架构以及启动流程，本章会继续介绍 kubelet 中的核心功能，kubelet 中包含数十个 manager 以及对 CNI、CRI、CSI 的调用。每个 manager 的功能各不相同，manager 之间也会有依赖关系，本文会介绍比较简单的 statusManager。</p>
<h3 id="statusmanager-源码分析"><a name="statusmanager-源码分析" class="anchor-navigation-ex-anchor" href="#statusmanager-源码分析"><i class="fa fa-link" aria-hidden="true"></i></a>statusManager 源码分析</h3>
<blockquote>
<p>kubernetes 版本：v1.16</p>
</blockquote>
<p>statusManager 的主要功能是将 pod 状态信息同步到 apiserver，statusManage 并不会主动监控 pod 的状态，而是提供接口供其他 manager 进行调用。</p>
<h4 id="statusmanager-的初始化"><a name="statusmanager-的初始化" class="anchor-navigation-ex-anchor" href="#statusmanager-的初始化"><i class="fa fa-link" aria-hidden="true"></i></a>statusManager 的初始化</h4>
<p>kubelet 在启动流程时会在 <code>NewMainKubelet</code> 方法中初始化其核心组件，包括各种 manager。</p>
<p><code>k8s.io/kubernetes/pkg/kubelet/kubelet.go:335</code></p>
<pre class="language-"><code>func NewMainKubelet() (*Kubelet, error) {
......
// statusManager 的初始化
klet.statusManager = status.NewManager(klet.kubeClient, klet.podManager, klet)
......
}
</code></pre><p><code>NewManager</code> 是用来初始化 statusManager 对象的，其中参数的功能如下所示：</p>
<ul>
<li>kubeClient：用于和 apiserver 交互；</li>
<li>podManager：负责内存中 pod 的维护；</li>
<li>podStatuses：statusManager 的 cache，保存 pod 与状态的对应关系；</li>
<li>podStatusesChannel：当其他组件调用 statusManager 更新 pod 状态时，会将 pod 的状态信息发送到podStatusesChannel 中；</li>
<li>apiStatusVersions：维护最新的 pod status 版本号，每更新一次会加1；</li>
<li>podDeletionSafety：删除 pod 的接口；</li>
</ul>
<p><code>k8s.io/kubernetes/pkg/kubelet/status/status_manager.go:118</code></p>
<pre class="language-"><code>func NewManager(kubeClient clientset.Interface, podManager kubepod.Manager, podDeletionSafety PodDeletionSafetyProvider) Manager {
return &manager{
kubeClient: kubeClient,
podManager: podManager,
podStatuses: make(map[types.UID]versionedPodStatus),
podStatusChannel: make(chan podStatusSyncRequest, 1000),
apiStatusVersions: make(map[kubetypes.MirrorPodUID]uint64),
podDeletionSafety: podDeletionSafety,
}
}
</code></pre><p>在初始化完成后，kubelet 会在 Run 方法中会以 goroutine 的方式启动 statusManager。</p>
<p><code>k8s.io/kubernetes/pkg/kubelet/kubelet.go:1398</code></p>
<pre class="language-"><code>func (kl *Kubelet) Run(updates <-chan kubetypes.PodUpdate) {
......
kl.statusManager.Start()
......
}
</code></pre><p>statusManager 的代码主要在 <code>k8s.io/kubernetes/pkg/kubelet/status/</code> 目录中，其对外暴露的接口有以下几个：</p>
<pre class="language-"><code>type Manager interface {
// 一个 interface 用来暴露给其他组件获取 pod status 的
PodStatusProvider
// 启动 statusManager 的方法
Start()
// 设置 pod 的状态并会触发一个状态同步操作
SetPodStatus(pod *v1.Pod, status v1.PodStatus)
// 设置 pod .status.containerStatuses 中 container 是否为 ready 状态并触发状态同步操作
SetContainerReadiness(podUID types.UID, containerID kubecontainer.ContainerID, ready bool)
// 设置 pod .status.containerStatuses 中 container 是否为 started 状态并触发状态同步操作
SetContainerStartup(podUID types.UID, containerID kubecontainer.ContainerID, started bool)
// 将 pod .status.containerStatuses 和 .status.initContainerStatuses 中 container 的 state 置为 Terminated 状态并触发状态同步操作
TerminatePod(pod *v1.Pod)
// 从 statusManager 缓存 podStatuses 中删除对应的 pod
RemoveOrphanedStatuses(podUIDs map[types.UID]bool)
}
</code></pre><p>pod 对应的 status 字段如下所示：</p>
<pre class="language-"><code>status:
conditions:
......
containerStatuses:
- containerID: containerd://64e9d88459b38e90c2a4b4d87db5acd180c820c855a55aabe38e4e11b9b83576
image: docker.io/library/nginx:1.9
imageID: sha256:f568d3158b1e871b713cb33aca5a9377bc21a1f644addf41368393d28c35e894
lastState: {}
name: nginx-pod
ready: true
restartCount: 0
started: true
state:
running:
startedAt: "2019-12-15T16:13:29Z"
podIP: 10.15.225.15
......
</code></pre><p>然后继续看 statusManager 的启动方法 <code>start</code>, 其主要逻辑为：</p>
<ul>
<li>1、设置定时器，<code>syncPeriod</code> 默认为 10s；</li>
<li>2、启动 <code>wait.Forever</code> goroutine 同步 pod 的状态，有两种同步方式，第一种是当监听到某个 pod 状态改变时会调用 <code>m.syncPod</code> 进行同步，第二种是当触发定时器时调用 <code>m.syncBatch</code> 进行批量同步；</li>
</ul>
<p><code>k8s.io/kubernetes/pkg/kubelet/status/status_manager.go:147</code></p>
<pre class="language-"><code>func (m *manager) Start() {
// 1、检查 kubeClient 是否被初始化
if m.kubeClient == nil {
klog.Infof("Kubernetes client is nil, not starting status manager.")
return
}
// 2、设置定时器
syncTicker := time.Tick(syncPeriod)
go wait.Forever(func() {
select {
// 3、监听 m.podStatusChannel channel，当接收到数据时触发同步操作
case syncRequest := <-m.podStatusChannel:
......
m.syncPod(syncRequest.podUID, syncRequest.status)
// 4、定时同步
case <-syncTicker:
m.syncBatch()
}
}, 0)
}
</code></pre><h4 id="syncpod"><a name="syncpod" class="anchor-navigation-ex-anchor" href="#syncpod"><i class="fa fa-link" aria-hidden="true"></i></a>syncPod</h4>
<p><code>syncPod</code> 是用来同步 pod 最新状态至 apiserver 的方法，主要逻辑为：</p>
<ul>
<li>1、调用 <code>m.needsUpdate</code> 判断是否需要同步状态，若 <code>apiStatusVersions</code> 中的 status 版本号小于当前接收到的 status 版本号或者 <code>apistatusVersions</code> 中不存在该 status 版本号则需要同步，若不需要同步则继续检查 pod 是否处于删除状态，若处于删除状态调用 <code>m.podDeletionSafety.PodResourcesAreReclaimed</code> 将 pod 完全删除；</li>
<li>2、从 apiserver 获取 pod 的 oldStatus；</li>
<li>3、检查 pod <code>oldStatus</code> 与 <code>currentStatus</code> 的 uid 是否相等，若不相等则说明 pod 被重建过；</li>
<li>4、调用 <code>statusutil.PatchPodStatus</code> 同步 pod 最新的 status 至 apiserver，并将返回的 pod 作为 newPod；</li>
<li>5、检查 newPod 是否处于 terminated 状态，若处于 terminated 状态则调用 apiserver 接口进行删除并从 cache 中清除，删除后 pod 会进行重建；</li>
</ul>
<p><code>k8s.io/kubernetes/pkg/kubelet/status/status_manager.go:514</code></p>
<pre class="language-"><code>func (m *manager) syncPod(uid types.UID, status versionedPodStatus) {
// 1、判断是否需要同步状态
if !m.needsUpdate(uid, status) {
klog.V(1).Infof("Status for pod %q is up-to-date; skipping", uid)
return
}