Can't add user to docker group

Question

I'm trying to set docker up on a new system, and when running docker info I get:

docker -v
=> Docker version 18.09.5, build e8ff056

docker info
=> Got permission denied while trying to connect to the Docker daemon
   socket at unix:///var/run/docker.sock: Get
   http://%2Fvar%2Frun%2Fdocker.sock/v1.39/info: dial unix 
   /var/run/docker.sock: connect: permission denied

Following the docs, I've tried:

sudo usermod -a -G docker $USER

Which returns no output. When I then run groups:

groups
=> mark adm cdrom sudo dip plugdev lpadmin sambashare

I can see a docker group exists:

less /etc/group | grep docker
=> docker:x:131:mark

And can see that it owns a socket running where the error message states:

ls -la /var/run/ | grep docker
=> 
drwx------  5 root                root                 120 May 25 14:54 docker
-rw-r--r--  1 root                root                   5 May 25 14:54 docker.pid
srw-rw----  1 root                docker                 0 May 25 14:54 docker.sock

So why can't I add myself to that group with sudo usermod -a -G docker $USER ?

Subdiaconate

I believe you need to login/restart for the changes to be completed. – Polemist

Your belief is correct, thanks! – Subdiaconate

On Ubuntu 20.04, in my case, "login/restart" literally meant I needed to _reboot_ for the changes to take effect, not merely restart the bash session. Wowzers. – Barbel

One gotcha to watch for is that you run groups to check if you've been added to the docker group whereas you probably need to run groups $USER. This is since according to man groups "if no USERNAME is specified, [groups will display groups] for the current process (which may differ if the groups database has changed)" – Glendon

Answer 1

You need to reload your shell in order to make the changes take effect. Often you need to reboot your shell process and possibly even restart your computer.

e.g

sudo usermod -aG docker $USER
sudo reboot

See @4Z4T4R answer and give a thumbs https://mcmap.net/q/415322/-can-39-t-add-user-to-docker-group

Load changes without quitting your shell

To avoid starting a new shell you can run. (Doesn't seem to work for all environments)

exec su -l $USER

This will create a new subshell with the loaded changes and replace your current shell with it.

If you need it to work now without restarting your computer

Another way if you just need to get it working now, is to change your primary group. This is only a temp solution as with any new shell you will need to apply it again.

export my_group=$(id -gn)
newgrp docker
newgrp $my_group

Documentation

You can also look at the offical documentation here https://docs.docker.com/engine/install/linux-postinstall/

Dimaggio

restarting the shell did not work for me, but newgrp docker did. Any idea why that would happen? – Balbriggan

Same issue here on ubuntu 20.04, newgrp docker seemed to work for me. sudo usermod -a -G docker $USER seemed to work periodically, but after reboot the group was lost. – Announce

Exactly the same problem on Ubuntu 19.10, for me only newgrp docker fixes it, but it's not persistent – Mcspadden

The newgrp command is very different from usermod -aG GROUP USER: the latter adds group GROUP to USER, without changing the primary group of USER; the newgrp creates a new shell and in that shell, the USER's primary group changes to GROUP! This is not likely the desired effect: the OP still wants files created by USER to belong to user's primary GROUP, but wants files owned by GROUP to be accessible by USER. Very completely different. – Breezeway

That is true, I updated the post to help maintain the same behaviour. It is not the ideal way to solve this issue but is a final option if nothing else is working for you. At this point even the offical docker documentation suggests doing this. I added the link to the post. – Dimaggio

Answer 2

In my case, on Ubuntu 20.04, run sudo reboot after this command:

$ sudo usermod -aG docker $USER

I literally needed to reboot my operating system (and machine) for the change to take effect. Restarting/reloading the bash session did not apply the new setting.

Sure, newgrp docker does the trick "on the fly" without restart/reboot/re-anything... but once the session terminates, POOF you're not in the docker group any longer.

Added this as a formal answer bc it genuinely solved the OP's---and my (identical)---problem.

Credit should go to @Omari Celestine for the suggestion, but because I suck at interpretation, I (and maybe you) need the literal disambiguation that this answer provides.

Barbel

I tried the usermod & reboot & doesn't work for me, the only thing working is newgrp docker – Anchie

Answer 3

Its a two step process technically. Run

sudo usermod -aG docker $USER

then,

sg docker -c "bash"

Corell

Answer 4

Change the permissions on the /var/run/docker.sock file and restart docker process.

sudo chown jenkins:jenkins /var/run/docker.sock
sudo 644 /var/run/docker.sock

Then,

sudo service docker restart

Doctrine

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center. – Methyl

Answer 5

Try this

sudo groupadd docker

sudo usermod -aG docker $USER

newgrp docker

Restart is required for the changes to take effect.

Empressement

Answer 6

Before running $docker info, Please make sure that the docker service up.

If not pls start the service by running below command.

$service docker start

Now you check the $docker info

Fifteenth