Installing Docker on Ubuntu
You can install Docker using APT to get the latest version. Here are the steps:
Update Ubuntu APT sources
1. Add new GPG key.
$ sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
2. Make sure that CA-certificates are installed.
$ sudo apt-get install apt-transport-https ca-certificates
3. Create a new /etc/apt/sources.list.d/docker.list file and add an entry for your Ubuntu operating system.
On Ubuntu Precise 12.04 (LTS)
deb https://apt.dockerproject.org/repo ubuntu-precise main
On Ubuntu Trusty 14.04 (LTS)
deb https://apt.dockerproject.org/repo ubuntu-trusty main
On Ubuntu Wily 15.10
deb https://apt.dockerproject.org/repo ubuntu-wily main
4. Update the APT index.
$ sudo apt-get update
5. Install Docker.
$ sudo apt-get install docker-engine
6. Start the docker daemon.
$ sudo service docker start
7. Create docker group and add your user.
$ sudo usermod -aG docker ubuntu
8. Verify docker is installed correctly.
$ docker run hello-world
Note that, as of February 17, 2016, Docker is officially supported on the these Ubuntu versions:
Ubuntu Wily 15.10
Ubuntu Trusty 14.04 (LTS)
Ubuntu Precise 12.04 (LTS)
Resource:
https://docs.docker.com/engine/installation/linux/ubuntulinux/