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Merge pull request #23404 from 2rs2ts/patch-1

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Fix ambiguity around behavior of preStop hook
This commit is contained in:
Kubernetes Prow Robot
2020-10-12 17:27:22 -07:00
committed by GitHub
parent caa4490191 96a27ce40f
commit 19e1b54436
1 changed files with 16 additions and 6 deletions
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content/en/docs/concepts/containers/container-lifecycle-hooks.md
+16 -6
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@@ -38,7 +38,7 @@ No parameters are passed to the handler.
This hook is called immediately before a container is terminated due to an API request or management event such as liveness probe failure, preemption, resource contention and others. A call to the preStop hook fails if the container is already in terminated or completed state.
It is blocking, meaning it is synchronous,
so it must complete before the call to delete the container can be sent.
so it must complete before the signal to stop the container can be sent.
No parameters are passed to the handler.
A more detailed description of the termination behavior can be found in
@@ -65,10 +65,21 @@ the Container ENTRYPOINT and hook fire asynchronously.
However, if the hook takes too long to run or hangs,
the Container cannot reach a `running` state.
The behavior is similar for a `PreStop` hook.
If the hook hangs during execution,
the Pod phase stays in a `Terminating` state and is killed after `terminationGracePeriodSeconds` of pod ends.
If a `PostStart` or `PreStop` hook fails,
`PreStop` hooks are not executed asynchronously from the signal
to stop the Container; the hook must complete its execution before
the signal can be sent.
If a `PreStop` hook hangs during execution,
the Pod's phase will be `Terminating` and remain there until the Pod is
killed after its `terminationGracePeriodSeconds` expires.
This grace period applies to the total time it takes for both
the `PreStop` hook to execute and for the Container to stop normally.
If, for example, `terminationGracePeriodSeconds` is 60, and the hook
takes 55 seconds to complete, and the Container takes 10 seconds to stop
normally after receiving the signal, then the Container will be killed
before it can stop normally, since `terminationGracePeriodSeconds` is
less than the total time (55+10) it takes for these two things to happen.
If either a `PostStart` or `PreStop` hook fails,
it kills the Container.
Users should make their hook handlers as lightweight as possible.
@@ -122,4 +133,3 @@ Events:
* Get hands-on experience
[attaching handlers to Container lifecycle events](/docs/tasks/configure-pod-container/attach-handler-lifecycle-event/).