Install Docker for Kata Containers on Debian

Note:

• This guide assumes you have already installed the Kata Containers packages.
• This guide allows for installation with systemd or sysVinit init systems.

1. Install the latest version of Docker with the following commands:

   Notes:

   • This step is only required if Docker is not installed on the system.
   • Docker version 18.09 removed devicemapper support. If you wish to use a block based backend, see the options listed on https://github.com/kata-containers/documentation/issues/407.

   $ sudo apt-get -y install apt-transport-https ca-certificates curl gnupg2 software-properties-common
   $ curl -fsSL https://download.docker.com/linux/$(. /etc/os-release; echo "$ID")/gpg | sudo apt-key add -
   $ sudo add-apt-repository "deb https://download.docker.com/linux/$(. /etc/os-release; echo "$ID") $(lsb_release -cs) stable"
   $ sudo apt-get update
   $ sudo -E apt-get -y install 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:

a. sysVinit

- with `sysVinit`, docker config is stored in `/etc/default/docker`, edit the options similar to the following:

```sh
$ sudo sh -c "echo '# specify docker runtime for kata-containers
DOCKER_OPTS=\"-D --add-runtime kata-runtime=/usr/bin/kata-runtime --default-runtime=kata-runtime\"' >> /etc/default/docker"
```

b. systemd (this is the default and is applied automatically if you select the automatic installation option)

```bash
$ 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
```

c. Docker daemon.json

Create docker configuration folder.

```
$ sudo mkdir -p /etc/docker
```

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

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

3. Restart the Docker systemd service with one of the following (depending on init choice):

a. `sysVinit`

```sh
$ sudo /etc/init.d/docker stop
$ sudo /etc/init.d/docker start
```

To watch for errors:

```sh
$ tail -f /var/log/docker.log
```

b. systemd

```bash
$ 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 to the host kernel version.