Recipe of Solution to Docker Permission Denied Problem

When i tried to run Docker container via maven command, I got an error  something like below:

The error message tells us that the user executing the process don't have privileges to access the Docker Engine daemon. The fix to this is to add the user to the `docker` group.
What is the recipe for that fix? Run the command below in the terminal of the machine executing the docker command.
sudo usermod -a -G docker $USER
Subsequent to it, don't forget to log-out and login or simply reboot, for the changes to take effect.