无法在装有/ etc / passwd和/ etc / shadow的docker容器中添加新用户 [英] Can not add new user in docker container with mounted /etc/passwd and /etc/shadow
问题描述
docker run -ti -v my_passwd:/etc/passwd -v my_shadow:/etc/shadow --rm centos
[root@681a5489f3b0 /]# useradd test # does not work !?
useradd: failure while writing changes to /etc/passwd
[root@681a5489f3b0 /]# ll /etc/passwd /etc/shadow # permission check
-rw-r--r-- 1 root root 157 Oct 8 10:17 /etc/passwd
-rw-r----- 1 root root 100 Oct 7 18:02 /etc/shadow
使用passwd时也会出现类似的问题:
The similar problem arises when using passwd:
[root@681a5489f3b0 /]# passwd test
Changing password for user test.
New password:
BAD PASSWORD: The password is shorter than 8 characters
Retype new password:
passwd: Authentication token manipulation error
我尝试过使用ubuntu映像,但是出现了同样的问题。
I have tried using the ubuntu image, but the same problem arises.
我可以手动在容器中编辑passwd文件和影子文件。
I can manually edit passwd file and shadow file from within container.
主机操作系统:CentOS 7-SELinux已禁用
Docker版本:1.8.2,build 0a8c2e3
Host OS: CentOS 7 - SELinux Disabled
Docker Version: 1.8.2, build 0a8c2e3
主机操作系统:CoreOS 766.4.0
Docker版本:1.7.1,构建df2f73d-dirty
Host OS: CoreOS 766.4.0
Docker version: 1.7.1, build df2f73d-dirty
我也在GitHub上发布了问题: https://github.com/docker/docker/issues/16857
I've also opened issue on GitHub: https://github.com/docker/docker/issues/16857
推荐答案
失败是因为 passwd
会处理一个临时文件,然后尝试将其重命名为 / etc / shadow
。失败是因为 / etc / shadow
是一个安装点-无法替换-导致此错误(使用 strace $ c捕获) $ c>):
It's failing because passwd
manipulates a temporary file, and then attempts to rename it to /etc/shadow
. This fails because /etc/shadow
is a mountpoint -- which cannot be replaced -- which results in this error (captured using strace
):
102 rename("/etc/nshadow", "/etc/shadow") = -1 EBUSY (Device or resource busy)
您可以从命令行轻松重现此内容:
You can reproduce this trivially from the command line:
# cd /etc
# touch foo
# mv foo shadow
mv: cannot move 'foo' to 'shadow': Device or resource busy
您可以通过装入包含<$ c的目录来解决此问题$ c> my_shadow 和 my_passwd
在其他地方,然后符号链接 / etc / passwd
和 / etc / shadow
适当地放在容器中:
You could work around this by mounting a directory containing my_shadow
and my_passwd
somewhere else, and then symlinking /etc/passwd
and /etc/shadow
in the container appropriately:
$ docker run -it --rm -v $PWD/my_etc:/my_etc centos
[root@afbc739f588c /]# ln -sf /my_etc/my_passwd /etc/passwd
[root@afbc739f588c /]# ln -sf /my_etc/my_shadow /etc/shadow
[root@afbc739f588c /]# ls -l /etc/{shadow,passwd}
lrwxrwxrwx. 1 root root 17 Oct 8 17:48 /etc/passwd -> /my_etc/my_passwd
lrwxrwxrwx. 1 root root 17 Oct 8 17:48 /etc/shadow -> /my_etc/my_shadow
[root@afbc739f588c /]# passwd root
Changing password for user root.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.
[root@afbc739f588c /]#
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