How to mount docker socket as volume in docker container with correct group

…衆ロ難τιáo~ 提交于 2019-12-02 18:10:19

A bit late, but this might help other users who are struggling with the same problem:

The problem here is that the docker group on your docker host has a different group id from the id of the docker group inside your container. Since the daemon only cares about the id and not about the name of the group your solution will only work if these id's match by accident.

The way to solve this is by either using tcp instead of using a unix socket by using the -H option when starting Docker engine. You should be very careful with this, as this allows anyone who has access to this port to gain root access to your system.

A more secure way of fixing this is making sure that the docker group inside the container ends up having the same group id as the docker group outside of the container. You can do this using build arguments for your docker build:

Dockerfile:

FROM jenkinsci
ARG DOCKER_GROUP_ID

USER root
RUN curl -o /root/docker.tgz https://get.docker.com/builds/Linux/x86_64/docker-1.12.5.tgz && tar -C /root -xvf /root/docker.tgz && mv /root/docker/docker /usr/local/bin/docker && rm -rf /root/docker*
RUN curl -L https://github.com/docker/compose/releases/download/1.7.1/docker-compose-`uname -s`-`uname -m` > /usr/local/bin/docker-compose && chmod +x /usr/local/bin/docker-compose
RUN groupadd -g $DOCKER_GROUP_ID docker && gpasswd -a jenkins docker
USER jenkins

And then building it using

docker build --build-arg DOCKER_GROUP_ID=`getent group docker | cut -d: -f3` -t my-jenkins-image .

After this you can run your image and have docker access as non-root

docker run -v /var/run/docker.sock:/var/run/docker.sock -p 8080:8080 -ti my-jenkins-image

Because this solution depends on supplying the correct group id to the docker daemon when the image is being built, this image would need to be built on the machine(s) where it is being used. If you build the image, push it and someone else pulls it on their machine, chances are that the group id's won't match again.

I used your dockerfile but did a small edit:

FROM jenkins
COPY plugins.txt /usr/share/jenkins/plugins.txt
RUN /usr/local/bin/plugins.sh /usr/share/jenkins/plugins.txt

USER root
RUN apt-get update
RUN groupadd docker && gpasswd -a jenkins docker
USER jenkins

After building the image I can start it using (I'm on centos7):

docker run -d \
-v /var/run/docker.sock:/var/run/docker.sock \
     -v $(which docker):/usr/bin/docker:ro \
     -v /lib64/libdevmapper.so.1.02:/usr/lib/x86_64-linux-gnu/libdevmapper.so.1.02 \
     -v /lib64/libudev.so.0:/usr/lib/x86_64-linux-gnu/libudev.so.0 \
     -p 8080:8080 \
     --name jenkins \
     --privileged=true -t -i \
test/jenkins

You tried to install the package docker.io inside your image. But this package is also on your host (otherwise it's not possible to run docker containers on it). So It's recommended to mount this to your container instead of installing it in your docker file. I think the mounted /lib64/... is specific for Centos 7.

$ docker exec -it 9fc27d5fcec1 bash
jenkins@9fc27d5fcec1:/$ whoami 
jenkins
jenkins@9fc27d5fcec1:/$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                               NAMES
9fc27d5fcec1        test                "/bin/tini -- /usr/lo"   6 minutes ago       Up 6 minutes        0.0.0.0:8080->8080/tcp, 50000/tcp   jenkins
易学教程内所有资源均来自网络或用户发布的内容,如有违反法律规定的内容欢迎反馈
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!