docker info
Cannot connect to the Docker daemon at 
tcp://localhost:2375/usr/lib/systemd/system/docker.socket. Is the docker daemon running?

Answer: I‘ve experienced this problem previously – and this is the way I worked around the problem.Let me know if this doesn’t fix the issue

1. Add your self to the docker group

   usermod -aG docker $USER

2. Fix permissions on docker socker and command.

   sudo chgrp docker /usr/bin/docker
sudo chgrp docker /var/run/docker.sock

   $ ll $(which docker)
-rwxr-xr-x 1 root docker 18991768 08.07.2017 22:57 /usr/bin/docker*

   $ ll /var/run/docker.sock
srw-rw---- 1 root docker 0 23.07.2017 10:21 /var/run/docker.sock

3. Add variables to config environment for docker command

   export DOCKER_HOST=unix:///var/run/docker.sock

4. Rest Docker

   sudo systemctl restart docker

Author: Jack Vamvas