kata-containers/install/docker/centos-docker-install.md

Install Docker for Kata Containers on CentOS

Note:

• This guide assumes you have already installed the Kata Containers packages.

1. Install Docker with the following commands:

   Notes:

   • This step is only required if Docker is not installed on the system.
   • Newer versions of Docker have removed devicemapper support so the following commands install the latest version, which includes devicemapper support.
   • To remove the lock on the docker package to allow it to be updated:

     $ sudo yum versionlock delete docker-ce
     

   $ sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
   $ sudo yum -y install 'docker-ce-18.06.2.ce-3*' yum-plugin-versionlock
   $ sudo yum versionlock docker-ce
   

   For more information on installing Docker please refer to the Docker Guide.

2. Configure Docker to use Kata Containers by default with one of the following methods:

   1. systemd

      $ sudo mkdir -p /etc/systemd/system/docker.service.d/
      $ cat <<EOF | sudo tee /etc/systemd/system/docker.service.d/kata-containers.conf
      [Service]
      ExecStart=
      ExecStart=/usr/bin/dockerd -D --add-runtime kata-runtime=/usr/bin/kata-runtime --default-runtime=kata-runtime
      EOF
      

   2. Docker daemon.json

      Add the following definitions to /etc/docker/daemon.json:

      {
        "default-runtime": "kata-runtime",
        "runtimes": {
          "kata-runtime": {
            "path": "/usr/bin/kata-runtime"
          }
        }
      }
      

3. Restart the Docker systemd service with the following commands:

   $ sudo systemctl daemon-reload
   $ sudo systemctl restart docker
   

4. Run Kata Containers

   You are now ready to run Kata Containers:

   $ sudo docker run busybox uname -a
   

   The previous command shows details of the kernel version running inside the container, which is different from the host kernel version.