Looking at docs there is no instruction on how to run it behind a proxy. https://docs.docker.com/installation/ubuntulinux/
Reading on forums, the instruction is to updat
For Ubuntu 14.04.2 LTS
Linux vagrant-ubuntu-trusty-64 3.13.0-54-generic #91-Ubuntu SMP Tue May 26 19:15:08 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
Edit you /etc/default/docker
file
sudo vim /etc/default/docker
Add this line at the bottom:
export http_proxy="http://PROXY_IP:PROXY_PORT"
Restart the docker
service
sudo service docker restart