CentOS Question posted in
The official documentation can be found here.

How to map volume for Jenkins in Dockers – CentOS

I have been trying to map volume from my host to docker container, while running jenkins, but failing.

This is what I tried so far:

I executed the following command:

docker run -p 8080:8080 -p 50000:50000 -v /var/jenkins_home:/var/jenkins_home jenkins/jenkins:lts

I am getting following error:

touch: cannot touch '/var/jenkins_home/copy_reference_file.log': Permission denied
Can not write to /var/jenkins_home/copy_reference_file.log. Wrong volume permissions?

I tried a lot of things, and last I followed the following steps from this link:

Jenkins wrong volume permissions

docker run -p 8080:8080 -p 50000:50000 -it jenkins bin/bash

Once inside the container’s shell run the id command and you’ll get results like:

uid=1000(jenkins) gid=1000(jenkins) groups=1000(jenkins)

Exit the container, go to the folder you are trying to map and run:

chown -R 1000:1000 .

On my machine I do not have user 1000 so I am trying to create it but failing to do so.

useradd -u 1000 jenkins

When I run the above command, I get the following error.

useradd: UID 1000 is not unique

My machine details are as follows:

NAME="CentOS Linux"
VERSION="7 (Core)"

The OS is running on Oracle VM Virtual Box.

I have tried couple of other things, but seems to be failing.

Any pointers will be appreciated.

Thanks.

Tags:

3

Answers


  1. Chosen as BEST ANSWER
    0

    I did some more RnD and tried following:

    I ran the following command

    docker volume create jenkins_volume

    This creates a volume jenkins_volume in following directory

    var/lib/docker/volumes

    If i do ll, i get the following details

    drwxr-xr-x. 3 root root 4096 Jul 26 07:51 jenkins_volume

    i.e. the user and group is root.

    Now if i try to run this command it works fine.

    docker run -p 8080:8080 -p 50000:50000 -v jenkins_volume:/var/jenkins_home jenkins/jenkins:lts

    Although I am not clear to me why earlier it was not working (as in the original question), even when the id and group was root:root for /var/jenkins_home.

    May be someone shed more light on this, but for now it am able to make progess.

    Thanks.


  2. 0

    tl;dr: You dont need add user jenkins with id 1000 on your host, the chown should be enough.

    Privilege mismatch is a common problem you often get when using bind mounts. The user running a process inside a container does not match the bind-mount privileges it tries to access.

    You can try to run the container as the host user that is allowed to access the bind mount, i.e. as the current host user docker run --user $(id -u):$(id -g) ...

    Then again there might be a specific user set in the image to run a process and this trick does not work. If you choose to keep using bind mounts you can change the permissions on the bind mount like you already did, i.e. chown -R 1000:1000 .. You dont need that user on your host system, it should still work, it will just show as user 1000 with gid 1000 on the host without a named user attached.

    I suggest to get used to use named mounts instead of bind mounts, it solves alot of the troubles you get with bind mounts.

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search