CODEWITHSUNDEEP
docker
Tristan
Tristan

Reputation: 9121

Strange error about permissions inside a docker container

I'm running an official tomcat image (https://github.com/docker-library/tomcat/tree/master/8.5/jre8) with customized permissions applied : I've created a tomcat:tomcat user and group and made him owner of /usr/local/tomcat and all subdirectories.

In /usr/local/tomcat, when I do "touch test" or "mkdir testdir", it works, but if I do the same thing in "work" subdirectory or any subdirectory, it fails.

tomcat@462080a55bca:/usr/local/tomcat$ ll | grep work
drwxr-x---  2 tomcat tomcat  4096 Jan 10 21:03 work

tomcat@462080a55bca:/usr/local/tomcat$ touch work/test
touch: cannot touch ‘work/test’: Permission denied

tomcat@462080a55bca:/usr/local/tomcat$ mkdir work/testdir
mkdir: cannot create directory ‘work/testdir’: Permission denied

Anyone can tell me why ?

Upvotes: 0

Views: 201

Answers (1)

Tristan
Tristan

Reputation: 9121

This is a bug in linux Kernel (and maybe also on aufs/overlay2). It's fixed in kernel >= 4.7 See here for more details : https://github.com/docker/docker/issues/30285

Additional informations from Justin Cormack (engineer at Docker) : "Many of these fixes are being backported to the stable 4.4 kernels", "The new Debian stable with 4.9 kernel will be out in a few months, and Docker for AWS and Azure also have 4.9 kernels." (It will actually be 4.10 for Debian, and maybe later than expected but still first half of 2017).

Upvotes: 2

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