[C API]: Cannot run generated binary without cargo run / configurable location for ONNX shared library

[radu-matei]

Right now, if you try to run the compiled helper binary wasmtime-onnx, you get the following error:

error loading shared libraries: libonnxruntime.so.1.6.0: cannot open shared object file: No such file or directory

This is because the binary is compiled with the ONNX shared library linked directly from the target/ directory.
See https://github.com/nbigaouette/onnxruntime-rs/blob/master/ONNX_Compilation_Notes.md

[radu-matei]

I managed to set the location of the shared library:

• first, set $ORT_LIB_LOCATION and $ORT_STRATEGY to the location of the local ONNX library and system.
• compile the binary binary again (the build script of onnxruntime-sys gets triggered when the environment variables change).
• set $LD_LIBRARY_PATH to the /lib directory of the local ONNX library.

➜ echo $ORT_LIB_LOCATION && echo $ORT_STRATEGY
/home/radu/onnx/onnxruntime-linux-x64-1.6.0
system

➜ cargo build --bin wasmtime-onnx
...

➜ LD_LIBRARY_PATH=/home/radu/onnx/onnxruntime-linux-x64-1.6.0/lib ./target/debug/wasmtime-onnx
error: The following required arguments were not provided:
    <module>

USAGE:
    wasmtime-onnx <module> --invoke <invoke>

This is fine for now, but we'll need a way to define this at runtime rather than at compile time, and with a different environment variable.

[radu-matei]

The approach taken by the Rust bindings for OpenVINO seems to be exactly what we are looking for - https://github.com/intel/openvino-rs/tree/main/crates/openvino-sys/src/linking

Also see chertov/onnxruntime-rs@b94870f

[radu-matei]

Documenting that expanding the LD_LIBRARY_PATH environment variable solves this issue should be enough to close this issue.