How to fix docker: Got permission denied issue

Question

I installed Docker in my machine where I have Ubuntu OS. After than I installed docker, when I run

sudo docker run hello-world

All it\'s ok

Answer 1

After an upgrade I got the permission denied. Doing the steps of 'mkb' post install steps don't have change anything because my user was already in the 'docker' group; I retry-it twice any way without success.

After an search hour this following solution finaly worked :

sudo chmod 666 /var/run/docker.sock

Solution came from Olshansk.

Look like the upgrade have recreate the socket without enough permission for the 'docker' group.

Problems

This hard chmod open security hole and after each reboot, this error start again and again and you have to re-execute the above command each time. I want a solution once and for all. For that you have two problems :

• 1) Problem with SystemD : The socket will be create only with owner 'root' and group 'root'.

  You can check this first problem with this command :

  ls -l /lib/systemd/system/docker.socket
  

  If every this is good, you should see 'root/docker' not 'root/root'.

• 2 ) Problem with graphical Login : https://superuser.com/questions/1348196/why-my-linux-account-only-belongs-to-one-group

  You can check this second problem with this command :

  groups
  

  If everything is correct you should see the docker group in the list. If not try the command

  sudo su $USER  -c groups
  

  if you see then the docker group it is because of the bug.

Solutions

If you manage to to get a workaround for the graphical login, this should do the job :

sudo chgrp docker /lib/systemd/system/docker.socket
sudo chmod g+w /lib/systemd/system/docker.socket

But If you can't manage this bug, a not so bad solution could be this :

sudo chgrp $USER /lib/systemd/system/docker.socket
sudo chmod g+w /lib/systemd/system/docker.socket

This work because you are in a graphical environnement and probably the only user on your computer. In both case you need a reboot (or an sudo chmod 666 /var/run/docker.sock)