Docker run armv7 images on mac

Question

My mac uses x86_64 hardware and in theory I shouldn't be able to run docker images built for armv7.

HOWEVER

Docker documentation says:

Docker Desktop provides binfmt_misc multi-architecture support, which means you can run containers for different Linux architectures such as arm, mips, ppc64le, and even s390x.

This does not require any special configuration in the container itself as it uses qemu-static from the Docker for Mac VM.

and I'm also reading articles like this one which confirm the above
docker run -it --rm arm32v7/debian /bin/bash

should work on a mac although it doesn't work for me:

Unable to find image 'arm32v7/debian:latest' locally
latest: Pulling from arm32v7/debian
Digest: sha256:9b61eaedd46400386ecad01e2633e4b62d2ddbab8a95e460f4e0057c612ad085
Status: Image is up to date for arm32v7/debian:latest
docker: Error response from daemon: image with reference arm32v7/debian was found but does not match the specified platform cpu architecture: wanted: amd64, actual: arm.
See 'docker run --help'.

I wonder whether I'm misunderstanding something.

Docker desktop community version 2.4.2.0 (48975) edge
Docker version 20.10.0-beta1, build ac365d7
MacOS version 10.15.7 (19H2)

Note: while researching the topic I've tryied to use qemu and ran:
docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
which has potentially interfered with the default behaviour.

Answer 1

I think my problem is related to this moby issue .

The fix was quite trivial as I only needed to add the --platform argument, in my case linux/arm or linux/arm/v7 :
docker run -it --rm arm32v7/debian /bin/bash
has become
docker run --platform=linux/arm -it --rm arm32v7/debian /bin/bash

and voila:

root@82c3ff8752d3:/# uname -a
Linux 82c3ff8752d3 5.4.39-linuxkit #1 SMP Fri May 8 23:03:06 UTC 2020 armv7l GNU/Linux