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

Question

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.

Answer 1

2019-02-16

Most of the steps were the same for me as the others has written. However, I was not able to add jenkins to the group docker using usermod with the mentioned solutions.

I tried the following command from the docker host, and from the running docker container:

sudo usermod -a -G docker jenkins

(I entered to the running docker container with the following command from the docker host:

docker exec -t -i my_container_id_or_name /bin/bash

)

Received from docker host:

usermod: user 'jenkins' does not exist

Received from docker container:

We trust you have received the usual lecture from the local System Administrator. It usually boils down to these three things:

#1) Respect the privacy of others.
#2) Think before you type.
#3) With great power comes great responsibility.

[sudo] password for jenkins:

I didnt know the password.

Without the sudo part of the command, in the docker container I received:

usermod: Permission denied. usermod: cannot lock /etc/passwd; try again later.

Solution: I entered to the running docker container from the docker host with the following command:

docker exec -t -i -u root my_container_id_or_name /bin/bash

Now, I entered as root, and issued the following command:

usermod -a -G docker jenkins

Then, from the docker host, I restarted my running docker container with the following command:

docker restart my_container_id_or_name

After that, I started the jenkins job and it finished with success.

I only used the root user to issue the usermod command for the user jenkins.