Now we've removed all of the older versions of NVIDIA-Docker. it's time to add the keys and repository to the typical apt-get repositories that you can pull from. First, in the Installing NVIDIA-Docker recipe, we need to add the appropriate key for  apt-get to communicate with the NVIDIA-Docker repository:

curl -s -L https://nvidia.github.io/nvidia-docker/gpgkey | 
  sudo apt-key add -
distribution=$(. /etc/os-release;echo $ID$VERSION_ID)

After adding the key, we add the repo to the sources that apt-get can pull from when installing packages:

curl -s -L https://nvidia.github.io/nvidia-docker/$distribution/nvidia-docker.list | 
  sudo tee /etc/apt/sources.list.d/nvidia-docker.list

Finally, an apt-get update allows apt-get to update its list of installable packages. Since we just added a new repository, the update will allow us to install the NVIDIA-Docker repository in the next step:

sudo apt-get update

Now we move on to the next step.