Docker for Mac does not respect the DOCKER_CONFIG var - docker/for-mac#2635
However, using launchctl you can get the desktop app to use a different .docker location.
- Create a plist file, I use environment.plistas I use this workaround for other apps.
- Insert the following into the plist file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">