I installed docker and there seems to be some issue.
$ docker ps
CONTAINER ID IMAGE COMMAND
docker-machine is a legacy stuff for OSX that operates with VirtualBox. What you should do is get rid of it completely, and then you should download the latest version of docker, that is called Docker for Mac
Make sure, you remove the legacy docker, and the docker-machine from your Mac before installing Docker for Mac. If you do not do that, the legacy docker binary will be favoured after the installation, and you will still get the error message, which says that cannot connect to the Docker daemon.