Description
One of the things that the NVIDIA Container Toolkit does is update the ldcache in the container so as to allow applications to discover the host driver libraries that have been injected. We also create (some) .so symlinks to match the files tracked by the driver installation. These point to the SONAME symlinks. For example: libcuda.so -> libcuda.so.1 -> libcuda.so.RM_VERSION. We create the libcuda.so symlinks before we run ldconfig, but libcuda.so is not present in the ldcache since we rely on running ldconfig to create the libcuda.so.1 symlink. This means that the ldcache in the container once it starts does not match expectations (i.e. the host state).
For example, on a host with the driver installed we have:
$ ldconfig -p | grep libcuda
libcuda.so.1 (libc6,x86-64) => /lib/x86_64-linux-gnu/libcuda.so.1
libcuda.so (libc6,x86-64) => /lib/x86_64-linux-gnu/libcuda.so
In a container:
$ docker run --rm -ti -e NVIDIA_VISIBLE_DEVICES=runtime.nvidia.com/gpu=all ubuntu
root@93984b5c459c:/# ldconfig -p | grep libcuda
libcuda.so.1 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libcuda.so.1
If we run ldconfig in the container we see the following:
root@93984b5c459c:/# ldconfig
root@93984b5c459c:/# ldconfig -p | grep libcuda
libcuda.so.1 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libcuda.so.1
libcuda.so (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libcuda.so
which matches the host state.
This also holds for the "legacy" code path since the symlink chain is only completed by running ldconfig once.
This seems inocent enough, but has the side effect that applications that run dlopen("libcuda.so", RTLD_LAZY); may not find the library if it is not in the standard library path (this could be the case for CDI).
A simple workaround is to inject the update-ldcache hook twice, but we may want to consider a two phase approach where we first run ldconfig with the -N flag to only update the links and then run ldconfig to update the cache.