IntraにDocker Registryを立てたときはNO_PROXYも忘れずに ref: http://qiita.com/hisamekms/items/fc47d0ccf2c69268ae71

docker.service

...
[Service]
...
Environment="HTTP_PROXY=YOUR.PROXY.HOST:PORT"
Environment="NO_PROXY=NO.PROXY.HOST1,NO.PROXY.HOST2"
ExecStart=/usr/bin/docker -d -s=btrfs -r=false -H fd://
...

file0.txt

# /etc/systemd/system/docker.service
...
[Service]
...
Environment="HTTP_PROXY=YOUR.PROXY.HOST:PORT"
Environment="NO_PROXY=NO.PROXY.HOST1,NO.PROXY.HOST2"
ExecStart=/usr/bin/docker -d -s=btrfs -r=false -H fd://
...

file1.txt

# /etc/sysconfig/docker
other_args="--exec-driver=lxc --selinux-enabled"
export HTTP_PROXY=YOUR.PROXY.HOST:PORT
export NO_PROXY=NO.PROXY.HOST1,NO.PROXY.HOST2