Script (derived from https://github.com/docker-32bit/ubuntu) to generate Ubuntu 32bit Docker images.

The generated Docker images are available via DockerHub.

Note:

In order to run docker images derived from a different platform architecture than the host (the architecture used to run the docker engine), the host kernel still needs to be configured to enable the binfmt-support for the foreign architecture. This can be done by simply via:
$ sudo apt install qemu-user-static

Additionally, the runtime in the container will need access to qemu--static binaries. This can be done two ways; by either mounting those binaries from the host to user/bin/ inside the container, or baking them into the image itself from the get-go (as done here in this repo's bootstrap setup). The current version of qemu being bundled is 3.1.

• qemu-aarch64-static was taken from the Debian package qemu-user-static_3.1+dfsg-8+deb10u3_amd64.deb.
• qemu-arm-static was taken from the Debian package qemu-user-static_3.1+dfsg-8+deb10u3_i386.deb.

The binary qemu-arm-static must be taken from a 32bit architecture (in this case i386) to work around this bug.

In order to use the bootstrap tooling, debootstrap must be installed. This can be done by simply via: $ sudo apt install debootstrap

Additionally when building from a different platform architecture than the target image, i.e. the architecture used to run the debootstrap and docker engine vs the architecture inside the source chroot, the host will again need binfmt-support for the kernel. As the debootstrap process downloads and copies in the qemu static binaries for emulation into the chroot before any execution is done inside the chroot, installing the qemu static binaries onto the host is then not essential.