Install docker on ubuntu 12.04

1. Update the kernel to 3.8 above

When 12.04 was installed, the kernel was 3.3, we need to update the kernel to 3.8 above to better support docker
sudo apt-get update
sudo apt-get install linux-image-generic-lts-raring linux-headers-generic-lts-raring
sudo reboot

then  we can check
stack@openstack:~$ uname -a
Linux openstack 3.13.0-29-generic #53-Ubuntu SMP Wed Jun 4 21:00:20 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

2. Add docker key to your local key repository

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9

you can check as
stack@openstack:~$ sudo apt-key list
/etc/apt/trusted.gpg
--------------------
pub 1024D/437D05B5 2004-09-12
uid Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
sub 2048g/79164387 2004-09-12

pub 1024D/FBB75451 2004-12-30
uid Ubuntu CD Image Automatic Signing Key <cdimage@ubuntu.com>

pub 4096R/C0B21F32 2012-05-11
uid Ubuntu Archive Automatic Signing Key (2012) <ftpmaster@ubuntu.com>

pub 4096R/EFE21092 2012-05-11
uid Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>

pub 2048R/A88D21E9 2013-08-16
uid Docker Release Tool (releasedocker) docker@dotcloud.com

3. Add the repository to your APT sources

#sudo sh –c “echo deb https://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list”
check by :

stack@openstack:~$ cat /etc/apt/sources.list.d/docker.list
deb https://get.docker.io/ubuntu docker main

4. Install docker

sudo apt-get update ; sudo apt-get install -y lxc-docker
check by
stack@openstack:~$ ps -ef | grep docker
root 1419 1 2 22:19 ? 00:00:55 /usr/bin/docker -d

5. Install Ubuntu to your local sandbox

sudo docker pull Ubuntu
check by
stack@openstack:~$ sudo docker ps -l
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a4c13d74f23a ubuntu:14.04 /bin/echo hello worl 11 minutes ago Exited (0) 11 minutes ago tender_heisenberg

6. Hello world now:

stack@openstack:~$ sudo docker run ubuntu /bin/echo hello world
hello world

now a standard docker is running on your ubuntu 12.4