docker buildx armv7 platform missing

Question

I am trying to build a docker image for a raspberry pi 4 (linux/arm/v7). I am using Ubuntu WSL. I have been able to build the image for Ubuntu WSL with no issues. I am using docker buildx to build the image for raspberry pi4 (armv7). I created the builder like this:

docker buildx create --name my_builder

But listing the builder it looks that the armv7 is missing along with other platforms. Any idea how is this possible? does Ubuntu WSL doesnt support this cross platform? Would I need to do this directly from Windows or some other host platform?

> docker buildx inspect
Name:   my_builder
Driver: docker-container

Nodes:
Name:      my_builder0
Endpoint:  unix:///var/run/docker.sock
Status:    running
Platforms: linux/amd64, linux/amd64/v2, linux/amd64/v3, linux/386

In case this help:

> docker buildx ls
NAME/NODE                 DRIVER/ENDPOINT             STATUS                 PLATFORMS
my_builder *              docker-container
  my_builder0 unix:///var/run/docker.sock             running                linux/amd64, linux/amd64/v2, linux/amd64/v3, linux/386
desktop-linux                                         protocol not available
default                   docker
  default                 default                     running                linux/amd64, linux/386

Answer 1

It should be possible by installing QEMU

sudo apt-get install -y qemu qemu-user-static

After that you should have more architectures/platforms to build images for.