Using systemd it’s rather simple to set specific environment variables for a specific application. In this example ill set a http(s) and noproxy settings for docker.

First we create systemd drop-in directory for the docker service:

sudo mkdir /etc/systemd/system/docker.service.d

Add  file called /etc/systemd/system/docker.service.d/http-proxy.conf that includes the HTTP_PROXY environment variable:

[Service]
Environment="HTTP_PROXY=http://proxy.internal:3128/"
Environment="HTTPS_PROXY=http://proxy.internal:3128/"
Environment="NO_PROXY=localhost,127.0.0.1/8"

Reload the daemon

$ sudo systemctl daemon-reload

Verify that the configuration has been loaded:

$ sudo systemctl cat docker.service

Restart Docker:

$ sudo systemctl restart docker