pyo3 compilation

[Sytten]

Hi there!

We are trying to cross-compile pyo3 to embed a python interpreter in our rust binary, this is proving to be a challenge and I was wondering if someone else had that working? We will have to build custom images, but any tips is appreciated.

Thanks

[Emilgardis]

The steps how to do this seem to be pretty well documented on

https://pyo3.rs/main/building_and_distribution.html#cross-compiling

So, should be something like

[build]
pre-build = "apt-get update && apt-get -y install python3.7"
[build.env]
passthrough = [
    "PYO3_CROSS=1",
]

[Emilgardis]

Maybe it'll suffice with libpython3.8-dev:$CROSS_DEB_ARCH? (couldn't find 3.7-dev in focal)

so

[build]
pre-build = "apt-get update && apt-get -y install libpython3.8-dev:$CROSS_DEB_ARCH"

if you want to use a dockerfile, you can do that also with

[build]
dockerfile = "Dockerfile"

see wiki

and cross will automatically build it and use it.

[Sytten]

This would most likely work for other linux architecture, but won't work for cross compilation to windows or macos.
I also posted a thread in pyo3 to get some thoughts: PyO3/pyo3#3123
I almost have a working solution, but I have a linker error and I am not sure why the target lib isn't sent to the linker.

[Sytten]

The dockerfile is the way to go:

FROM --platform=linux/arm64/v8 python:3.8.16 AS python

FROM ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main

RUN apt-get update && apt-get -y install python3.8

COPY --from=python /usr/local/lib/ /opt/sysroot/usr/lib/

I also had to add RUSTFLAGS=-L /opt/sysroot/usr/lib to the env

[diptanu]

@Sytten I am having a bunch of trouble cross compiling Indexify from Ubuntu x86_64 for aarch64, can you give me some code pointers to your solution? I am getting some linker errors with the docker file you pasted above even with the env being passed into the container environment.

[Sytten]

I ended up not going this route so I don't think I can help you much. Usually linking error means missing native lib for the target architecture.