自定义Docker映像不继承CMD [英] Custom Docker image doesn't inherit CMD

问题描述

我有一个使用以下Dockerfile构建的映像：

I have an image built using the following Dockerfile:

FROM php:7-fpm
COPY docker-entrypoint.sh /usr/local/bin/docker-entrypoint
RUN chmod +x /usr/local/bin/docker-entrypoint
ENTRYPOINT ["docker-entrypoint"]

它使用以下bash脚本的自定义入口点：

It uses a custom entrypoint which is the following bash script:

#!/bin/bash
set -e
echo "STARTING PHP FPM, CMD $@"
docker-php-entrypoint "$@"

在其 Dockerfile 是 CMD [ php-fpm]

现在，我希望此命令在映像中被继承。但是，当我运行图像时，该命令为空。这是 docker run 命令的输出：

Now I expected this command to be inherited in my image. However, when I run the image, the command is empty. Here is the output of the docker run command:

启动PHP FPM，CMD

STARTING PHP FPM, CMD

但是，如果我将 CMD [ php-fpm] 复制到自定义<$的末尾c $ c> Dockerfile ，输出为

However, if I copy CMD ["php-fpm"] to the end of my custom Dockerfile, the output is

启动PHP FPM，CMD php-fpm

STARTING PHP FPM, CMD php-fpm

[2017年11月1日20:04:02]注意：fpm正在运行，pid 7

[01-Nov-2017 20:04:02] NOTICE: fpm is running, pid 7

[2017年11月1日20:04:02]注意：已准备好处理连接

[01-Nov-2017 20:04:02] NOTICE: ready to handle connections

为什么不继承父级的 CMD 指令？

Why isn't the parent's CMD directive inherited?

推荐答案

这种行为试图变得更加直观，但是我同意这有点令人困惑。您会在此处看到原始问题。问题在于，大多数人在子图像中定义 ENTRYPOINT 不再需要父图像中的 CMD 。

This behavior is trying to be more intuitive, but I agree that it's a bit confusing. You see the original issue here. That problem was that most people defining the ENTRYPOINT in a child image no longer wanted the CMD from the parent image.

根据当前行为，如果在子图像中定义 ENTRYPOINT ，则 CMD 将从父图像中删除，因此如果需要进行设置，则需要重新定义。

With the current behavior, if you define an ENTRYPOINT in a child image, the CMD from the parent image will be null'd out, so you'll need to redefine it if you need to have it set.

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