This is a script and a Dockerfile to build a Ubuntu Precise 32 bit docker image, based on https://github.com/daald/docker-brew-ubuntu-core-32bit.
download official clould image:
./download_cloudimg.sh
build docker image:
docker build -t $(whoami)/docker-ubuntu-precise-core-i386 .
$ docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ouyi/ubuntu-precise-core-i386 latest 7c870020bc74 2 days ago 115.7 MB
In a Dockerfile, you can use (you may need to replace the user name)
FROM ouyi/docker-ubuntu-precise-core-i386