How can I make docker-compose pull images using a socks5 proxy?

Looks like this feature has been recently added to docker, particularly in version 1.11.0. Though there isn't enough documentation about its usage, setting the ALL_PROXY environment variable should work, according to this comment.

$ export ALL_PROXY=socks5://localhost:port 
$ docker pull image

I'm not sure about docker-compose at the moment. If your primary aim is to speed up the download process using socks5, you might be able to achieve the purpose by manually pulling images using docker pull before finally running docker-compose up.