254 lines
12 KiB
Markdown
254 lines
12 KiB
Markdown
---
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title: 容器生命周期回调
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content_type: concept
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weight: 30
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---
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<!--
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reviewers:
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- mikedanese
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- thockin
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title: Container Lifecycle Hooks
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content_type: concept
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weight: 30
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-->
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<!-- overview -->
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<!--
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This page describes how kubelet managed Containers can use the Container lifecycle hook framework
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to run code triggered by events during their management lifecycle.
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-->
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这个页面描述了 kubelet 管理的容器如何使用容器生命周期回调框架，
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藉由其管理生命周期中的事件触发，运行指定代码。
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<!-- body -->
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<!--
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## Overview
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Analogous to many programming language frameworks that have component lifecycle hooks, such as Angular,
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Kubernetes provides Containers with lifecycle hooks.
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The hooks enable Containers to be aware of events in their management lifecycle
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and run code implemented in a handler when the corresponding lifecycle hook is executed.
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-->
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## 概述
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类似于许多具有生命周期回调组件的编程语言框架，例如 Angular、Kubernetes 为容器提供了生命周期回调。
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回调使容器能够了解其管理生命周期中的事件，并在执行相应的生命周期回调时运行在处理程序中实现的代码。
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<!--
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## Container hooks
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There are two hooks that are exposed to Containers:
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-->
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## 容器回调
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有两个回调暴露给容器：
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`PostStart`
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<!--
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This hook is executed immediately after a container is created.
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However, there is no guarantee that the hook will execute before the container ENTRYPOINT.
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No parameters are passed to the handler.
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-->
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这个回调在容器被创建之后立即被执行。
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但是，不能保证回调会在容器入口点（ENTRYPOINT）之前执行。
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没有参数传递给处理程序。
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`PreStop`
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<!--
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This hook is called immediately before a container is terminated due to an API request or management
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event such as a liveness/startup probe failure, preemption, resource contention and others. A call
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to the `PreStop` hook fails if the container is already in a terminated or completed state and the
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hook must complete before the TERM signal to stop the container can be sent. The Pod's termination
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grace period countdown begins before the `PreStop` hook is executed, so regardless of the outcome of
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the handler, the container will eventually terminate within the Pod's termination grace period. No
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parameters are passed to the handler.
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-->
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在容器因 API 请求或者管理事件（诸如存活态探针、启动探针失败、资源抢占、资源竞争等）
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而被终止之前，此回调会被调用。
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如果容器已经处于已终止或者已完成状态，则对 preStop 回调的调用将失败。
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在用来停止容器的 TERM 信号被发出之前，回调必须执行结束。
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Pod 的终止宽限周期在 `PreStop` 回调被执行之前即开始计数，所以无论
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回调函数的执行结果如何，容器最终都会在 Pod 的终止宽限期内被终止。
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没有参数会被传递给处理程序。
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<!--
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A more detailed description of the termination behavior can be found in
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[Termination of Pods](/docs/concepts/workloads/pods/pod-lifecycle/#pod-termination).
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-->
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有关终止行为的更详细描述，请参见
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[终止 Pod](/zh/docs/concepts/workloads/pods/pod-lifecycle/#termination-of-pods)。
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<!--
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### Hook handler implementations
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Containers can access a hook by implementing and registering a handler for that hook.
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There are two types of hook handlers that can be implemented for Containers:
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-->
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### 回调处理程序的实现
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容器可以通过实现和注册该回调的处理程序来访问该回调。
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针对容器，有两种类型的回调处理程序可供实现：
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<!--
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* Exec - Executes a specific command, such as `pre-stop.sh`, inside the cgroups and namespaces of the Container.
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Resources consumed by the command are counted against the Container.
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* HTTP - Executes an HTTP request against a specific endpoint on the Container.
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-->
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* Exec - 在容器的 cgroups 和名称空间中执行特定的命令（例如 `pre-stop.sh`）。
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命令所消耗的资源计入容器的资源消耗。
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* HTTP - 对容器上的特定端点执行 HTTP 请求。
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<!--
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### Hook handler execution
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When a Container lifecycle management hook is called,
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the Kubernetes management system executes the handler according to the hook action,
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`httpGet` and `tcpSocket` are executed by the kubelet process, and `exec` is executed in the container.
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-->
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### 回调处理程序执行
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当调用容器生命周期管理回调时，Kubernetes 管理系统根据回调动作执行其处理程序，
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`httpGet` 和 `tcpSocket` 在kubelet 进程执行，而 `exec` 则由容器内执行 。
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<!--
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Hook handler calls are synchronous within the context of the Pod containing the Container.
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This means that for a `PostStart` hook,
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the Container ENTRYPOINT and hook fire asynchronously.
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However, if the hook takes too long to run or hangs,
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the Container cannot reach a `running` state.
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-->
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回调处理程序调用在包含容器的 Pod 上下文中是同步的。
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这意味着对于 `PostStart` 回调，容器入口点和回调异步触发。
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但是，如果回调运行或挂起的时间太长，则容器无法达到 `running` 状态。
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<!--
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`PreStop` hooks are not executed asynchronously from the signal
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to stop the Container; the hook must complete its execution before
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the TERM signal can be sent.
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If a `PreStop` hook hangs during execution,
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the Pod's phase will be `Terminating` and remain there until the Pod is
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killed after its `terminationGracePeriodSeconds` expires.
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This grace period applies to the total time it takes for both
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the `PreStop` hook to execute and for the Container to stop normally.
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If, for example, `terminationGracePeriodSeconds` is 60, and the hook
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takes 55 seconds to complete, and the Container takes 10 seconds to stop
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normally after receiving the signal, then the Container will be killed
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before it can stop normally, since `terminationGracePeriodSeconds` is
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less than the total time (55+10) it takes for these two things to happen.
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`PreStop` hooks are not executed asynchronously from the signal
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to stop the Container; the hook must complete its execution before
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the signal can be sent.
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If a `PreStop` hook hangs during execution,
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the Pod's phase will be `Terminating` and remain there until the Pod is
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killed after its `terminationGracePeriodSeconds` expires.
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This grace period applies to the total time it takes for both
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the `PreStop` hook to execute and for the Container to stop normally.
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If, for example, `terminationGracePeriodSeconds` is 60, and the hook
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takes 55 seconds to complete, and the Container takes 10 seconds to stop
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normally after receiving the signal, then the Container will be killed
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before it can stop normally, since `terminationGracePeriodSeconds` is
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less than the total time (55+10) it takes for these two things to happen.
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-->
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`PreStop` 回调并不会与停止容器的信号处理程序异步执行；回调必须在
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可以发送信号之前完成执行。
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如果 `PreStop` 回调在执行期间停滞不前，Pod 的阶段会变成 `Terminating`
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并且一致处于该状态，直到其 `terminationGracePeriodSeconds` 耗尽为止，
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这时 Pod 会被杀死。
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这一宽限期是针对 `PreStop` 回调的执行时间及容器正常停止时间的总和而言的。
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例如，如果 `terminationGracePeriodSeconds` 是 60，回调函数花了 55 秒钟
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完成执行，而容器在收到信号之后花了 10 秒钟来正常结束，那么容器会在其
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能够正常结束之前即被杀死，因为 `terminationGracePeriodSeconds` 的值
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小于后面两件事情所花费的总时间（55+10）。
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<!--
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If either a `PostStart` or `PreStop` hook fails,
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it kills the Container.
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-->
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如果 `PostStart` 或 `PreStop` 回调失败，它会杀死容器。
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<!--
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Users should make their hook handlers as lightweight as possible.
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There are cases, however, when long running commands make sense,
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such as when saving state prior to stopping a Container.
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-->
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用户应该使他们的回调处理程序尽可能的轻量级。
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但也需要考虑长时间运行的命令也很有用的情况，比如在停止容器之前保存状态。
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<!--
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### Hook delivery guarantees
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Hook delivery is intended to be *at least once*,
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which means that a hook may be called multiple times for any given event,
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such as for `PostStart` or `PreStop`.
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It is up to the hook implementation to handle this correctly.
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-->
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### 回调递送保证
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回调的递送应该是 *至少一次*，这意味着对于任何给定的事件，
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例如 `PostStart` 或 `PreStop`，回调可以被调用多次。
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如何正确处理被多次调用的情况，是回调实现所要考虑的问题。
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<!--
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Generally, only single deliveries are made.
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If, for example, an HTTP hook receiver is down and is unable to take traffic,
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there is no attempt to resend.
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In some rare cases, however, double delivery may occur.
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For instance, if a kubelet restarts in the middle of sending a hook,
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the hook might be resent after the kubelet comes back up.
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-->
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通常情况下，只会进行单次递送。
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例如，如果 HTTP 回调接收器宕机，无法接收流量，则不会尝试重新发送。
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然而，偶尔也会发生重复递送的可能。
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例如，如果 kubelet 在发送回调的过程中重新启动，回调可能会在 kubelet 恢复后重新发送。
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<!--
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### Debugging Hook handlers
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The logs for a Hook handler are not exposed in Pod events.
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If a handler fails for some reason, it broadcasts an event.
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For `PostStart`, this is the `FailedPostStartHook` event,
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and for `PreStop`, this is the `FailedPreStopHook` event.
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You can see these events by running `kubectl describe pod <pod_name>`.
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Here is some example output of events from running this command:
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-->
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### 调试回调处理程序
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回调处理程序的日志不会在 Pod 事件中公开。
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如果处理程序由于某种原因失败，它将播放一个事件。
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对于 `PostStart`，这是 `FailedPostStartHook` 事件，对于 `PreStop`，这是 `FailedPreStopHook` 事件。
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您可以通过运行 `kubectl describe pod <pod_name>` 命令来查看这些事件。
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下面是运行这个命令的一些事件输出示例:
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```
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Events:
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FirstSeen LastSeen Count From SubobjectPath Type Reason Message
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--------- -------- ----- ---- ------------- -------- ------ -------
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1m 1m 1 {default-scheduler } Normal Scheduled Successfully assigned test-1730497541-cq1d2 to gke-test-cluster-default-pool-a07e5d30-siqd
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1m 1m 1 {kubelet gke-test-cluster-default-pool-a07e5d30-siqd} spec.containers{main} Normal Pulling pulling image "test:1.0"
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1m 1m 1 {kubelet gke-test-cluster-default-pool-a07e5d30-siqd} spec.containers{main} Normal Created Created container with docker id 5c6a256a2567; Security:[seccomp=unconfined]
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1m 1m 1 {kubelet gke-test-cluster-default-pool-a07e5d30-siqd} spec.containers{main} Normal Pulled Successfully pulled image "test:1.0"
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1m 1m 1 {kubelet gke-test-cluster-default-pool-a07e5d30-siqd} spec.containers{main} Normal Started Started container with docker id 5c6a256a2567
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38s 38s 1 {kubelet gke-test-cluster-default-pool-a07e5d30-siqd} spec.containers{main} Normal Killing Killing container with docker id 5c6a256a2567: PostStart handler: Error executing in Docker Container: 1
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37s 37s 1 {kubelet gke-test-cluster-default-pool-a07e5d30-siqd} spec.containers{main} Normal Killing Killing container with docker id 8df9fdfd7054: PostStart handler: Error executing in Docker Container: 1
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38s 37s 2 {kubelet gke-test-cluster-default-pool-a07e5d30-siqd} Warning FailedSync Error syncing pod, skipping: failed to "StartContainer" for "main" with RunContainerError: "PostStart handler: Error executing in Docker Container: 1"
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1m 22s 2 {kubelet gke-test-cluster-default-pool-a07e5d30-siqd} spec.containers{main} Warning FailedPostStartHook
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```
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## {{% heading "whatsnext" %}}
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<!--
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* Learn more about the [Container environment](/docs/concepts/containers/container-environment/).
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* Get hands-on experience
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[attaching handlers to Container lifecycle events](/docs/tasks/configure-pod-container/attach-handler-lifecycle-event/).
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-->
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* 进一步了解[容器环境](/zh/docs/concepts/containers/container-environment/)
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* 动手实践，[为容器生命周期事件添加处理程序](/zh/docs/tasks/configure-pod-container/attach-handler-lifecycle-event/)
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