Please provide 32-bit runtime capable containers about docker-brew-ubuntu-core

[tianon]

We just consume the Ubuntu Core builds as-is here, so the 12.04 build has the i386 architecture added already, but the 14.04 and 15.04 builds do not. Adding it is really simple, though:

FROM ubuntu:14.04
RUN dpkg --add-architecture i386
RUN apt-get update && apt-get install -y libc6:i386 && rm -rf /var/lib/apt/lists/*

[xnox]

@tianon this should be enabled in the default ubuntu images that one pulls with "docker pull ubuntu".

[tianon]

If it's not enabled in the packages provided by Ubuntu, what's the justification? Docker does not officially support 32bit platforms. The tarballs provided by Ubuntu do come in an i386 variant, but it's a completely separate project to actually build and support such a thing right now, since Docker is not interested in 32bit support currently.

[xnox]

@tianon it is enabled by default on normal Ubuntu Desktop & Server installations by default. That is an amd64 ubuntu installation can execute i386 binaries. From docker point of view it's a 64bit host, guest and platform, it just happens that workloads inside it can execute i386 binaries.

[tianon]

These tarballs are the stock rootfs tarballs provided by Canonical (specifically, https://partner-images.canonical.com/core/), so I'm not actually permitted to do more modification to them than what's already being done here (they're very specific about providing these tarballs built from their own systems for us to call this Ubuntu -- I'm essentially just the proxy maintainer here).

That being said, I've got two points of interest for you. One is https://hub.docker.com/r/i386/ubuntu/ (for a pure 32bit image). The other is the following:

$ docker pull ubuntu:precise > /dev/null
$ docker run -it --rm ubuntu:precise dpkg --print-foreign-architectures
i386
$ docker pull ubuntu:trusty > /dev/null
$ docker run -it --rm ubuntu:trusty dpkg --print-foreign-architectures
$ docker pull ubuntu:wily > /dev/null
$ docker run -it --rm ubuntu:wily dpkg --print-foreign-architectures
$ docker pull ubuntu:xenial > /dev/null
$ docker run -it --rm ubuntu:xenial dpkg --print-foreign-architectures

So, this definitely used to be standard (as evidenced by precise having it), but is no longer considered to be as such.