Relationship of nvidia-container-runtime and CDI

[ereslibre]

Hello,

Thank you for all your work. I am writing to ask for a clarification in terms of the current projects and components.

Based on NVIDIA/nvidia-docker#1268 (comment) and https://docs.nvidia.com/datacenter/cloud-native/container-toolkit/latest/arch-overview.html, it's not completely clear to me what is the future relationship between cmd/nvidia-container-runtime{-hook,.cdi,.legacy} within this project and CDI.

While we need to support older runtimes, it's clear that we need to provide nvidia-container-runtime in the meantime, but do you foresee that CDI will completely deprecate it? Or is it intended for it to cover use cases that won't be covered by CDI?

Thank you.

[ereslibre]

I also found https://forums.developer.nvidia.com/t/what-is-unique-about-the-nvidia-container-runtime-does-cdi-replace-it/265975/5 that points to the complete replacement of the nvidia-container-runtime for CDI-compliant runtimes.

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[ArangoGutierrez]

You are right: Yes, CDI is the intended successor and will at some point deprecate the legacy nvidia-container-runtime wrapper.

Here's the relationship:

1. The Past (Wrapper): The nvidia-container-runtime was a "shim" created before a standard existed. It wrapped a runtime (like runc) to intercept commands and manually inject GPU support.

2. The Future (Standard): CDI (Container Device Interface) is that standard. It's a vendor-neutral CNCF specification that lets runtimes discover and inject devices themselves.

The nvidia-container-toolkit's job has evolved. Its primary role is now to use the nvidia-ctk tool to generate the CDI specification files (e.g., /var/run/cdi/nvidia.yaml).

Modern container runtimes like containerd, CRI-O, Podman, and Docker Engine (v25.0+) all have native CDI support. They read this spec file directly, which removes the need for the old wrapper.

To answer your questions directly:

• Will CDI deprecate the wrapper? Yes.

• Does the wrapper cover use cases CDI doesn't? No. The legacy wrapper is kept only for backwards compatibility with older runtimes or to translate old user commands (like --gpus all) into modern CDI injections. But is our hope that slowly users will move to newer versions of docker/containerd/crio... and will be able to leverage CDI as the standard.

We are closing this as answered.

[ereslibre]

Thanks a lot for the super detailed and explicit answers @ArangoGutierrez, very appreciated.