run jenkins pipeline agent with sudo - docker

Question

I have an Jenkins Server running in an docker container and have access to docker an the host system, so far it is working well. Now I want to set up a pipeline testing an script inside an docker container.
Jenkinsfile:
pipeline {
agent { docker 'nginx:1.11' }
stages {
stage('build') {
steps {
sh 'nginx -t'
}
}
}
}
Error Message:
> + docker pull nginx:1.11
>
> Warning: failed to get default registry endpoint from daemon (Got
> permission denied while trying to connect to the Docker daemon socket
> at unix:///var/run/docker.sock: Get
> http://%2Fvar%2Frun%2Fdocker.sock/v1.29/info: dial unix
> /var/run/docker.sock: connect: permission denied). Using system
> default: https://index.docker.io/v1/
>
> Got permission denied while trying to connect to the Docker daemon
> socket at unix:///var/run/docker.sock: Post
> http://%2Fvar%2Frun%2Fdocker.sock/v1.29/images/create?fromImage=nginx&tag=1.11:
> dial unix /var/run/docker.sock: connect: permission denied
>
> script returned exit code 1
My problem is that jenkins needs to run the docker command with sudo, but how to say the agent running the command with sudo?

Answer 1

I have faced the same issue. After analysing the console log, I have found that the reason is that the Docker Jenkins Plugin starts a new container with a specific option -u 107:112:
...
docker run -t -d -u 107:112 ...
...
After trying many options such as: add jenkins to sudo group (it did not work because jenkins user does not exist in container), add USER root into Dockerfile, ... but none of them do the trick.
Finally I have found a solution that is using args in docker agent to overwrite the -u option. This is my Jenkinsfile:
pipeline {
agent {
docker {
image 'ubuntu'
args '-u root:sudo -v $HOME/workspace/myproject:/myproject'
}
}
stages {
stage("setup_env") {
steps {
sh 'apt-get update -y'
sh 'apt-get install -y git build-essential gcc cmake make'
}
}
stage("install_dependencies") {
steps {
sh 'apt-get install -y libxml2-dev'
}
}
stage("compile_dpi") {
steps {
sh 'cd /myproject && make clean && make -j4'
}
}
stage("install_dpi") {
steps {
sh 'cd /myproject && make install'
}
}
stage("test") {
steps {
sh 'do some test here'
}
}
}
post {
success {
echo 'Do something when it is successful'
bitbucketStatusNotify(buildState: 'SUCCESSFUL')
}
failure {
echo 'Do something when it is failed'
bitbucketStatusNotify(buildState: 'FAILED')
}
}
}
There's maybe a security issue here but it is not the problem in my case.

Answer 2

I'd solve the problem differently, matching the jenkins group id inside the container to that of the docker socket you've mounted a volume. I do this with an entrypoint that runs as root, looks up the gid of the socket, and if that doesn't match that of the gid inside the current container, it does a groupmod to correct it inside the container. Then I drop privileges to the jenkins user to launch Jenkins. This entrypoint run on every startup, but fairly transparently to the Jenkins app that is launched.
All the steps to perform this are included in this github repo: https://github.com/sudo-bmitch/jenkins-docker/

Answer 3

You can work around that by:
1- In your Dockerfile add jenkins to the sudoers file:
RUN echo "jenkins ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
2- Add an extra step in your Jenkinsfile to give jenkins the right permissions to use docker:
pipeline {
agent none
stages {
stage("Fix the permission issue") {
agent any
steps {
sh "sudo chown root:jenkins /run/docker.sock"
}
}
stage('Step 1') {
agent {
docker {
image 'nezarfadle/tools'
reuseNode true
}
}
steps {
sh "ls /"
}
}
}
}

Answer 4

As others have suggested, the issue is that jenkins does not have permission to run docker containers. Let's go over the ways you could launch jenkins first, and then see what could be done in each of these ways.
1. running jenkins manually
Surely you could download & run jenkins with java as suggested in here. In this method, you could do several things to allow your jenkins user to use docker:
a. give jenkins user root access:
I do not suggest this way, after all you are giving your pipelines access to everything! So you probably do not want this to happen.
b. add jenkins user to docker group
Like explained here you could manage docker as non-root user. just add your user to docker group and thats all. I recommend it if you know who is going to use docker (cause well, you are giving him root access in docker in a way).
c. make docker rootless
This is a new feature docker added to its arsenal recently. You could read in detail what it implies here. To tell you the truth I am not a fan of this feature! The reason is that you can not (at least I could not find a way) to make it work for a user in a container (as you need to stop docker service to make it happen), also I had some difficulties configing dns when using rootless mode. But it should be fine if you are not in a container.
2. running jenkins in docker
This method is more troublesome actually! I struggled with the ways I could use docker in jenkins container, but in the end got the results needed, so was worth the effort.
To run docker in jenkins (which is also a docker container itself) you have three ways:
1. use dind (docker in docker)
It is pretty straight forward, you run dind image & connect docker in jenkins container to the dind, without any special permission handling you can use docker at will.
2. use dood (docker outside of docker)
mount docker path as a volume in the docker run script for your jenkins, note that you need to use one of the two ways I explained above (in running jenkins manually) to be able to use docker, it could be a bit tricky but possible.
3. run agent as a docker in a different environment & connect remote agent in jenkins
At last it is possible to run the agent separately & connecting the remote agent in jenkins. Although this does not exactly answer your question, but is a way you could use.
These ways for just running a docker in jenkins, you will probably have some issues after you ran a docker as agent, like having permission issues in the agent container itself, which is most likely because of the agent's user (if you like, you could access the user with command
docker exec -it [agent container id] whoami
e.g. in this sample the user in agent is node
agent {
docker { image 'node:14-alpine' }
}
steps{
sh 'npm i -g random'
}
so it would throw an error because the node user does not have permission to install npm module globally (I know, it is weird!)
so as luongnv89 mentioned, you could change the user running the docker like this
agent {
docker { image 'node:14-alpine' args '-u root' }
}
Hope this was helpful understanding the whole picture. 😊

Answer 5

What worked for me was
node() {
String jenkinsUserId = sh(returnStdout: true, script: 'id -u jenkins').trim()
String dockerGroupId = sh(returnStdout: true, script: 'getent group docker | cut -d: -f3').trim()
String containerUserMapping = "-u $jenkinsUserId:$dockerGroupId "
docker.image('image')
.inside(containerUserMapping + ' -v /var/run/docker.sock:/var/run/docker.sock:ro') {
sh "..."
}
}
This way the user in the container still uses the jenkins user id + group id to avoid permissions conflicts with shared data but is also member of the docker group inside container which is required to access the docker socket (/var/run/docker.sock)
I prefer this solution as it doesn't require any additional scripts or dockerfiles

Answer 6

I just had the same exact issue. You need to add jenkins user to docker group:
DOCKER_SOCKET=/var/run/docker.sock
DOCKER_GROUP=docker
JENKINS_USER=jenkins
if [ -S ${DOCKER_SOCKET} ]; then
DOCKER_GID=$(stat -c '%g' ${DOCKER_SOCKET})
sudo groupadd -for -g ${DOCKER_GID} ${DOCKER_GROUP}
sudo usermod -aG ${DOCKER_GROUP} ${JENKINS_USER}
fi
# Start Jenkins service
sudo service jenkins restart
After you run the above, pipelines successfully start docker

Answer 7

I might have found a reasonably good solution for this.
Setup
I run Jenkins as a container and use it to build containers on the dockerhost it's running on. To do this, I pass /var/run/docker.sock as a volume to the container.
Just to reiterate the disclaimer some other people already stated: Giving access to the docker socket is essentially like giving root access to the machine - be careful!
I assume that you've already installed docker into your Jenkins Image.
Solution
This is based on the fact, that the docker binary is not in the first directory of $PATH. We basically place a shell script that runs sudo docker instead of just the plain docker command (and passes the parameters along).
Add a file like this to your jenkins repository and call it docker_sudo_overwrite.sh:
#! /bin/sh
# This basically is a workaround to add sudo to the docker command, because aliases don't seem to work
# To be honest, this is a horrible workaround that depends on the order in $PATH
# This file needs to be place in /usr/local/bin with execute permissions
sudo /usr/bin/docker $#
Then extend your Jenkins Dockerfile like this:
# Now we need to allow jenkins to run docker commands! (This is not elegant, but at least it's semi-portable...)
USER root
## allowing jenkins user to run docker without specifying a password
RUN echo "jenkins ALL=(ALL) NOPASSWD: /usr/bin/docker" >> /etc/sudoers
# Create our alias file that allows us to use docker as sudo without writing sudo
COPY docker_sudo_overwrite.sh /usr/local/bin/docker
RUN chmod +x /usr/local/bin/docker
# switch back to the jenkins-user
USER jenkins
This gives the jenkins service user the ability to run the docker binary as root with sudo (without providing a password). Then we copy our script to /usr/local/bin/docker which "overlays" the actual binary and runs it with sudo. If it helps, you can look at my example on Github.

Answer 8

Same issue here where.
[...]
agent { docker 'whatever_I_try_doesnt_work'} # sudo, jenkins user in dockerroot group etc
[...]
So my workaround is to add it as one of the steps in the the build stage of the pipeline as follow:
pipeline {
agent any
stages {
stage('Build') {
steps {
sh 'sudo docker pull python:3.5.1'
}
}
}
}