[Python] cargo build with pyo3 uses a weird /install prefix for lib

I have tried to set either PYO3_CROSS_LIB_DIR or PYO3_PYTHON, both from terminal or in my build.rs but I keep having this /install as prefix everywhere and consequently my bin is not working.

I'm using

• pyenv for managing python versions
• mac os 15.3.2 on Apple M2.
• a venv managed by uv.
• pyo3 = { version = "0.23.4" }

my builds.rs looks like

use dotenvy::dotenv_override;
use std::env;

fn main() {
if let Err(err) = dotenv_override() {
eprintln!("Warning: Failed to load .env file: {err}");
}

// Build time dependencies
if let Ok(lib_path) = env::var("LIBRARY_PATH") {
println!("cargo:rustc-link-search={lib_path}");
println!("cargo:rerun-if-env-changed=LIBRARY_PATH");
}

// Link time dependencies
if let Ok(ld_library_path) = env::var("LD_LIBRARY_PATH") {
println!("cargo:rustc-link-arg=-Wl,-rpath,{ld_library_path}");
println!("cargo:rerun-if-env-changed=LD_LIBRARY_PATH");
}

if let Ok(dyld_library_path) = env::var("DYLD_LIBRARY_PATH") {
println!("cargo:rustc-link-arg=-Wl,-rpath,{dyld_library_path}");
println!("cargo:rerun-if-env-changed=DYLD_LIBRARY_PATH");
}
}


when I run PYO3_PRINT_CONFIG=1 cargo b I see

-- PYO3_PRINT_CONFIG=1 is set, printing configuration and halting compile --
implementation=CPython
version=3.10
shared=true
abi3=false
lib_name=python3.10
lib_dir=/install/lib
executable=/Users/clementwalter/Documents/kkrt-labs/keth/.venv/bin/python
pointer_width=64
build_flags=
python_framework_prefix=
suppress_build_script_link_lines=false


so here I already see this /install and I don't know where it comes from.

once built, using otool I see

$ otool -L target/release/keth-run
target/release/keth-run:
/install/lib/libpython3.10.dylib (compatibility version 3.10.0, current version 3.10.0)
/usr/lib/libiconv.2.dylib (compatibility version 7.0.0, current version 7.0.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1351.0.0)


if then I try to run, it fails

dyld[41034]: Library not loaded: /install/lib/libpython3.10.dylib
Referenced from: <7D8217ED-521B-3870-B777-1DAFA99B7940> /Users/clementwalter/Documents/kkrt-labs/keth/target/debug/keth-run
Reason: tried: '/install/lib/libpython3.10.dylib' (no such file)


if I export the DYLD path

export DYLD_LIBRARY_PATH=$HOME/.local/share/uv/python/cpython-3.10.15-macos-aarch64-none/lib


it actually starts but raises and again I see all these /install prefixes

Could not find platform independent libraries <prefix>
Could not find platform dependent libraries <exec_prefix>
Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
Python path configuration:
PYTHONHOME = (not set)
PYTHONPATH = (not set)
program name = 'python3'
isolated = 0
environment = 1
user site = 1
import site = 1
sys._base_executable = '/Users/clementwalter/Documents/kkrt-labs/keth/target/debug/keth-run'
sys.base_prefix = '/install'
sys.base_exec_prefix = '/install'
sys.platlibdir = 'lib'
sys.executable = '/Users/clementwalter/Documents/kkrt-labs/keth/target/debug/keth-run'
sys.prefix = '/install'
sys.exec_prefix = '/install'
sys.path = [
'/install/lib/python310.zip',
'/install/lib/python3.10',
'/install/lib/lib-dynload',
]
Fatal Python error: init_fs_encoding: failed to get the Python codec of the filesystem encoding
Python runtime state: core initialized
ModuleNotFoundError: No module named 'encodings'

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