[SOLVED] debootstrap can't create ubuntu old i386 image for docker

debootstrap can't create ubuntu old i386 image for docker

I'm trying to create a docker image with debootstrap. I'd like to create an ubuntu 8.04 i386 image. When I run

sudo debootstrap --verbose --arch=i386 hardy hardy http://old-releases.ubuntu.com/ubuntu/

then

sudo tar -C hardy -c . | sudo docker import - hardy

It creates the image but when I check the arch inside the container with

uname -m

it gives me x86_64 and not i386 as I requested before.

Any suggestion would be greatly appreciated. Thanks

SOLUTION

One way of getting around this problem (see the answer) is add ENTRYPOINT ["linux32"] to the Dockerfile

Solution

Because the architecture comes from the kernel, which comes from the host, not the container. For example, here is the uname output of two very different distribtuions:

$ docker run alpine uname -a
Linux 5ef5dac8a8ac 4.1.13-boot2docker #1 SMP Fri Nov 20 19:05:50 UTC 2015 x86_64 Linux
$ docker run debian uname -a
Linux c47f04c71efb 4.1.13-boot2docker #1 SMP Fri Nov 20 19:05:50 UTC 2015 x86_64 GNU/Linux

They both assume the kernel and architecture of the host. An even better answer than mine: https://superuser.com/a/889474/73766