[Misc]Easier access to the nccl library

[Cyuchuan]

[Misc]Easier access to the nccl library

When I install vllm-nccl it downloads libnccl.so to home/.config/vllm/cu12/libnccl.so.2.18.1. I like to migrate it to the libs of the conda environment for ease of use in production, so I generally migrate it to the conda lib directory for that. Generally the application will specify LD_LIBRARY_PATH to look for the so file, but originally it only searched for libnccl.so.2 in LD_LIBRARY_PATH, but now it extends LD_LIBRARY_PATH to search for libnccl.so.2* files.

[youkaichao]

I intentionally avoid the glob search format. It is ambiguous when you have multiple so files in the same directory.

If you want vllm to use a specific nccl library, just set VLLM_NCCL_SO_PATH . This will skip the search.