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nvidia-docker.md

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Description

nvidia-docker is a thin wrapper on top of docker and act as a drop-in replacement for the docker command line interface. This binary is provided as a convenience to automatically detect and setup GPU containers leveraging NVIDIA hardware. Refer to the internals section if you don't intend to use it.

Internally, nvidia-docker calls docker and relies on the NVIDIA Docker plugin to discover driver files and GPU devices. The command used by nvidia-docker can be overridden using the environment variable NV_DOCKER:

# Running nvidia-docker with a custom docker command
NV_DOCKER='sudo docker -D' nvidia-docker <docker-options> <docker-command> <docker-args>

Note that nvidia-docker only modifies the behavior of the run and create Docker commands. All the other commands are just pass-through to the docker command line interface. As a result, you can't execute GPU code when building a Docker image.

GPU isolation

GPUs are exported through a list of comma-separated IDs using the environment variable NV_GPU. An ID is either the index or the UUID of a given device.
Device indexes are similar to the ones reported by the nvidia-docker-plugin REST interface, nvidia-smi, or when running CUDA code with CUDA_DEVICE_ORDER=PCI_BUS_ID, it is however different from the default CUDA ordering. By default, all GPUs are exported.

# Running nvidia-docker isolating specific GPUs by index
NV_GPU='0,1' nvidia-docker <docker-options> <docker-command> <docker-args>
# Running nvidia-docker isolating specific GPUs by UUID
NV_GPU='GPU-836c0c09,GPU-b78a60a' nvidia-docker <docker-options> <docker-command> <docker-args>

Running it locally

If the nvidia-docker-plugin is installed on your host and running locally, no additional step is needed. nvidia-docker will perform what is necessary by querying the plugin when containers using NVIDIA GPUs need to be launched.

Running it remotely

Using nvidia-docker remotely requires nvidia-docker-plugin running on the remote host machine.
The remote host target can be set using the environment variable DOCKER_HOST or NV_HOST.

The rules are as follows:

  • If NV_HOST is set then it is used for contacting the plugin.
  • If NV_HOST is not set but DOCKER_HOST is set then NV_HOST defaults to the DOCKER_HOST location using the http protocol on port 3476 (more below)

The specification of NV_HOST is defined as:

[(http|ssh)://][<ssh-user>@][<host>][:<ssh-port>]:[<http-port>]

The http protocol requires the nvidia-docker-plugin to be listening on a reachable interface (by default nvidia-docker-plugin only listens on localhost). Opting for ssh however, only requires valid SSH credentials (either a password or a private key in your ssh-agent).

# Run CUDA on the remote host 10.0.0.1 using HTTP
DOCKER_HOST='10.0.0.1:' nvidia-docker run cuda

# Run CUDA on the remote host 10.0.0.1 using SSH
NV_HOST='ssh://10.0.0.1:' nvidia-docker -H 10.0.0.1: run cuda

# Run CUDA on the remote host 10.0.0.1 using SSH with custom user and ports
DOCKER_HOST='10.0.0.1:' NV_HOST='ssh://foo@10.0.0.1:22:80' nvidia-docker run cuda