Docker: Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock

I am new to docker. I just tried to use docker in my local machine(Ubuntu 16.04) with Jenkins.

I configured a new job with below pipeline script.

node {
    stage('Build') {
      docker.image('maven:3.3.3').inside {
        sh 'mvn --version'
      }
    }
}

But it fails with below error.

Solution 1:

The user jenkins needs to be added to the group docker:

sudo usermod -a -G docker jenkins

Then restart Jenkins.

Edit

If you arrive to this question of stack overflow because you receive this message from docker, but you don't use jenkins, most probably the error is the same: your unprivileged user does not belong to the docker group.

You can do:

sudo usermod -a -G docker [user]

Insert your user name where [user] is.

You can check it was successful by doing grep docker /etc/group and see something like this:

docker:x:998:[user]

in one of the lines.

Then change your users group ID to docker:

newgrp docker

Finally, log out and log in again

Solution 2:

My first solutions was:

usermod -aG docker jenkins
usermod -aG root jenkins
chmod 664 /var/run/docker.sock

But none of them work for me, I tried:

chmod 777 /var/run/docker.sock

That works, but I don't know if it is the right call.