Permission Denial Message

What is the source of the permission denial message?

=>Read command lines:
sudo docker ps
sudo ls /var/lib/docker/
sudo ls /var/lib/docker/volumes
sudo ls /var/lib/docker/vfs/dir

docker run -v /var/lib/mysql --name=my_datastore -d busybox echo 'My Datastore’
docker run -v /var/lib/html --name=my_datastore -d busybox echo ‘My Datastore’

docker ps -a

docker inspect my_datastore |less

sudo ls

docker run --name my_mysql -e MYSQL_ROT_PASSWORD=mysecretpassword --volume-from my_datastore -d mysql

docker ps

docker inspect my_sql |less

<mysql port 3306>

docker run --link=my_mysql:mysql -p 80:80 -d wordpress

docker ps

=>Error message from Putty Log:

WARNING: No limit swap support
WPUser@WPMeetup:~$ docker ps -a
FATA[0000] Get http:///var/run/docker.sock/v1.18/containers/json?all=1: dial Unix /var/run/docker.sock: permission denied. Are you trying to connect to a TLS-enabled daemon without TLS?