### You can define an HTTP proxy for the Docker service in the file /usr/lib/systemd/system/ docker.service.
[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.com
After=network.target docker.socket
Requires=docker.socket
[Service]
Type=notify
EnvironmentFile=-/etc/sysconfig/docker
ExecStart=/usr/bin/docker -d -H fd:// $OPTIONS
LimitNOFILE=1048576
LimitNPROC=1048576
Environment="HTTP_PROXY=http://proxy.example.com:80/" "NO_PROXY=localhost,127.0.0.0/8"
[Install]
Also=docker.socket