file-permissions – 如何将文件添加到没有root权限的docker容器

docker run -it tomcat /bin/bash
tomcat@06359f7cc4db:/usr/local/tomcat$

如果我指示Dockerfile将文件复制到该容器,则该文件具有权限644,并且所有者为root.据我所知,这似乎是合理的,因为Dockerfile中的所有命令都以root身份运行.但是,如果我尝试将该文件的所有权更改为tomcat：tomcat,则会出现Operation not allowed错误.

为什么我不能更改复制到该图像的文件的权限？

如何复制：

mkdir docker-addfilepermission
cd docker-addfilepermission
touch test.txt
echo 'FROM tomcat
COPY test.txt /usr/local/tomcat/webapps/
RUN chown tomcat:tomcat /usr/local/tomcat/webapps/test.txt' > Dockerfile

docker build .

docker build的输出.：

Sending build context to Docker daemon 3.072 kB
Sending build context to Docker daemon 
Step 0 : FROM tomcat
 ---> 44859847ef64
Step 1 : COPY test.txt /usr/local/tomcat/webapps/
 ---> Using cache
 ---> a2ccb92480a4
Step 2 : RUN chown tomcat:tomcat /usr/local/tomcat/webapps/test.txt
 ---> Running in 208e7ff0ec8f
chown: changing ownership of '/usr/local/tomcat/webapps/test.txt': Operation not permitted
2014/11/01 00:30:33 The command [/bin/sh -c chown tomcat:tomcat /usr/local/tomcat/webapps/test.txt] returned a non-zero code: 1