TL;DR

See this gist

Problem

Most of Microsoft Azure’s Python packages have uAMQP (azure-uamqp-python) as a dependency, hence if you’re developing any automation involving Azure with Python, you’d almost certainly need to install it in your pipeline. Under the hood, Python uAMQP uses its C counterpart azure-uamqp-c as an extension, therefore that’s required as an appropriate byte-compiled library for the target architecture, system and Python version the pipeline is running on.

In most cases, third-party Python packages that requires C extensions are shipped in archives where the Python code is packaged alongside the compiled extensions. Such archives are called wheels and can be installed as any other third-party package, using Pip, given that pre-built wheels targeting architecture, system and Python version Pip is installing on, are provided and available on the PyPI repository for the package.

Microsoft is publishing uAMQP Python wheels targeting Windows, Linux and MacOS, and for all live major Python 3 versions (3.7+). The only problem is that the only targeted architecture is x86_64 (see last uAMQP release on PyPI).

To be fair the source code is well engineered and can be fairly easily compiled for Linux on Arm architectures, in fact uAMQP GitHub repo, features build scripts for Python 3.5 on armV7 (which could probably work on a Raspberry PI 2 see here) but the Manylinux one is strictly targeting x86_64.

So as arm64v8 based servers are becoming widely adopted by public Cloud providers, I find quite peculiar the lack of arm64 pre-built wheels on PyPI. It’s definitely not a technical challenge/burden for uAMQP maintainers (I think), and I hope they’ll start providing them, and so are other devs on azure-uamqp-python’s Issues on GitHub.

Don’t get me wrong, I’m really glad the direction Microsoft took in the last decade, heavily investing on Open Source and Python. Kudos to them!

A solution

So in the meantime, if you need to build uAMQP for your Linux system running on Arm, below is a build script that should do the trick. It requires docker and an image provided by the amazing Manylinux project.

Cross compile aarch64 on x86_64

Note that you can use the same script to cross compile for aarch64 on a Linux x86_64 machine, thanks to the very clever qemu-user-static docker image by simply running the following container before the above script:

docker run --rm --privileged multiarch/qemu-user-static --reset -p yes

I’m not going to go into details on how the above works as it’s a bit out of the scope of this post, but I strongly recommend to everyone reading about it as what they did is a beautiful hack and, in my opinion, shows why running containers in privileged mode can be both powerful and extremely dangerous at the same time.