如何在ENTRYPOINT数组中使用Docker环境变量？ [英] How do I use Docker environment variable in ENTRYPOINT array?

问题描述

如果我设置一个环境变量，说 ENV ADDRESSEE = world ，我想在入口点脚本中使用它连接成一个固定的字符串，如：

If I set an environment variable, say ENV ADDRESSEE=world, and I want to use it in the entry point script concatenated into a fixed string like:

ENTRYPOINT ["./greeting", "--message", "Hello, world!"]

与 world 是环境变量的值，我该怎么做？我尝试使用Hello，$ ADDRESSEE，但似乎不起作用，因为它需要 $ ADDRESSEE

with world being the value of the environment varible, how do I do it? I tried using "Hello, $ADDRESSEE" but that doesn't seem to work, as it takes the $ADDRESSEE literally.

推荐答案

您使用的是ENTRYPOINT的 exec表单。与 shell表单不同， exec表单不调用命令shell。这意味着不会发生正常的shell处理。例如，$ code> ENTRYPOINT [echo，$ HOME] 不会在$ HOME上执行变量替换。如果你想要shell处理，那么可以使用 shell窗体或直接执行shell，例如： ENTRYPOINT [sh，-c，echo，$ HOME] 。

当使用exec窗体并直接执行一个shell时，就像shell窗体一样，它是正在进行环境变量扩展的shell，不是码头（从 Dockerfile参考）

You're using the exec form of ENTRYPOINT. Unlike the shell form, the exec form does not invoke a command shell. This means that normal shell processing does not happen. For example, ENTRYPOINT [ "echo", "$HOME" ] will not do variable substitution on $HOME. If you want shell processing then either use the shell form or execute a shell directly, for example: ENTRYPOINT [ "sh", "-c", "echo", "$HOME" ].
When using the exec form and executing a shell directly, as in the case for the shell form, it is the shell that is doing the environment variable expansion, not docker.(from Dockerfile reference)

在你的情况下，我将使用 shell窗体

In your case, I would use shell form

ENTRYPOINT ./greeting --message "Hello, $ADDRESSEE\!"

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