无法让Docker扩展文件头的ARG定义 [英] Can't get Docker to expand ARG define at head of file

问题描述

我有一个基于Windows 10的Dockerfile，我想与柯南一起使用.我的问题是我无法让Docker扩展我在文件开头定义的ARG.在此示例中:

I have a Dockerfile that is based on Windows 10 that I want to use with conan. My problem is that I cannot get Docker to expand an ARG I defined at the head of the file. In this sample:

ARG conan_repository=https://feeds.genetec.com/artifactory/api/conan/conan
ARG conan_remote=genetec

FROM mcr.microsoft.com/windows:1903

RUN conan remote add ${conan_remote ${conan_repository}

或

RUN conan remote add $conan_remote $conan_repository

总是以

C:\>conan remote list
conan-center: https://conan.bintray.com [Verify SSL: True]
$conan_remote: $conan_repository [Verify SSL: True]

在我连接到图像后手动添加柯南遥控器效果很好.

Adding the conan remote manually after I connected to the image works well.

我看不到在文档中找到与此有关的任何内容吗?

I can't seen to find anything on the docs about this?

推荐答案

将 ARG 行移到 FROM 行之后.

在Dockerfile参考中，请参见了解ARG和FROM之间的交互方式.特别是:

In the Dockerfile reference, see Understand how ARG and FROM interact. In particular:

在 FROM 之前声明的 ARG 在构建阶段之外，因此不能在 FROM 之后的任何指令中使用它

An ARG declared before a FROM is outside of a build stage, so it can’t be used in any instruction after a FROM.

您可以使用 ARG 来控制要从哪个图像开始(例如为基础图像选择特定的标签)，在这种情况下，必须先使用 ARG .否则，您需要将 ARG 放在 FROM 之后，并且如果在多阶段Dockerfile的多个部分中使用了相同的 ARG ，则需要在每个阶段重复一次.

You can use ARG to control which image you’re starting from (like picking a specific tag for the base image), in which case ARG has to come first. Otherwise, you need to put ARG after FROM, and if the same ARG is used in multiple parts of a multi-stage Dockerfile, you need to repeat it for each stage.

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