父 docker 中的 CMD 是否被子 docker 映像中的 CMD/ENTRYPOINT 覆盖? [英] Is CMD in parent docker overriden by CMD/ENTRYPOINT in child docker image?

问题描述

我正试图弄脏 docker.我知道 CMD 或 ENTRYPOINT 用于指定 docker 映像的启动/可运行命令，并且 CMD 被 ENTRYPOINT.但我不知道，当父 docker 映像也有 CMD OR ENTRYPOINT 或 BOTH 时，它是如何工作的?

I am trying to get my hands dirty on docker. I know that CMD or ENTRYPOINT is used to specify the start/runnable command for docker image and CMD is overridden by ENTRYPOINT. But I don't know, how does it works, when parent docker image, also has CMD OR ENTRYPOINT or BOTH ?

子图像是否从父 docker 图像继承这些值?如果是这样，那么父图像中的 ENTRYPOINT 会覆盖子图像中的 CMD 吗?

Does child image inherit those values from parent docker image ? If so, then does ENTRYPOINT in parent image override CMD in child image ?

我知道这样的问题已经在 https://github.com/docker/compose/问题/3140.但是，讨论已经很老了(2-3 年前)，并没有清楚地回答我的问题.

I know that such question is already discussed at https://github.com/docker/compose/issues/3140. But, the discussion is quite old(before 2-3 years) and it doesn't answer my question clearly.

提前致谢.

推荐答案

如果你在子图像中定义了一个 ENTRYPOINT，它会将 CMD 的值清空为在这个问题中确定.目的是避免出现令人困惑的情况，即入口点作为 args 传递给您不再想运行的命令.

If you define an ENTRYPOINT in a child image, it will null out the value of CMD as identified in this issue. The goal is to avoid a confusing situation where an entrypoint is passed as args a command you no longer want to run.

除此特定情况外，ENTRYPOINT 和 CMD 的值是继承的，并且可以被子图像甚至同一 Dockerfile 的后续步骤单独覆盖.图像中只有一个值，最后一个定义的值具有优先权.

Other than this specific situation, the value of ENTRYPOINT and CMD are inherited and can be individually overridden by a child image or even a later step of the same Dockerfile. Only one value for each of these will ever exist in an image with the last defined value having precedence.

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