在mkdir之后触摸文件时，构建Dockerfile失败 [英] Building Dockerfile fails when touching a file after a mkdir

问题描述

我是Docker的新人，尝试用简单的Dockerfile构建一个图像：

I'm new to Docker and try to build an image with a simple Dockerfile:

FROM jenkins
USER root
RUN mkdir -pv /home/a/b
RUN touch /home/a/b/test.txt
RUN mkdir -pv /var/jenkins_home/a/b
RUN touch /var/jenkins_home/a/b/test.txt
USER jenkins

当我构建它，它失败与以下输出：

When I build it, it fails with the following output:

Step 0 : FROM jenkins
Step 1 : USER root
Step 2 : RUN mkdir -pv /home/a/b
  mkdir: created directory '/home/a'
  mkdir: created directory '/home/a/b'
Step 3 : RUN touch /home/a/b/test.txt
Step 4 : RUN mkdir -pv /var/jenkins_home/a/b
  mkdir: created directory '/var/jenkins_home/a'
  mkdir: created directory '/var/jenkins_home/a/b'
Step 5 : RUN touch /var/jenkins_home/a/b/test.txt
  touch: cannot touch '/var/jenkins_home/a/b/test.txt': No such file or directory

任何人告诉我，我在这里失踪了为什么第一个mkdir&触摸组合工作，第二个不是？

Can anyone tell me, what I am missing here? Why does the first mkdir & touch combination work and the second does not?

推荐答案

查看 https://registry.hub.docker.com/u/library/jenkins/ ，似乎/ var / jenkins_home是一个卷。您只能在容器运行时创建文件，可能是使用卷映射，如

Looking at https://registry.hub.docker.com/u/library/jenkins/, it seems that /var/jenkins_home is a volume. You can only create files there while the container is running, presumably with a volume mapping like

docker run ... -v /your/jenkins/home:/var/jenkins_home ...

docker构建过程对于共享卷。

The docker build process knows nothing about shared volumes.

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