install: improve Docker installation for openSUSE

Editing systemd unit files to customize Docker for Kata may generate conflicts
with what's specified in /etc/sysconfig/docker, so use that file directly.

Also, libcgroup1 dependency is wrong for newer distros, and should be
pulled automatically for older ones.

Signed-off-by: Marco Vedovati <mvedovati@suse.com>

install/docker/opensuse-docker-install.md

@@ -1,4 +1,4 @@
-# Install Docker for Kata Containers on openSUSE Leap/Tumbleweed
+# Install Docker for Kata Containers on openSUSE
 
 > **Note:**
 >
@@ -14,24 +14,24 @@
    >   If you wish to use a block based backend, see the options listed on https://github.com/kata-containers/documentation/issues/407.
 
    ```bash
-   $ sudo zypper -n install libcgroup1
    $ sudo zypper -n install docker
    ```
 
    For more information on installing Docker please refer to the
    [Docker Guide](https://software.opensuse.org/package/docker).
 
-2. Configure Docker to use Kata Containers by default with one of the following methods:
+2. Configure the Docker daemon to use Kata Containers by default, with one of the following methods:
 
-   1. systemd
+   1. Specify the runtime options in `/etc/sysconfig/docker`:
 
        ```bash
-       $ sudo mkdir -p /etc/systemd/system/docker.service.d/
+       $ DOCKER_SYSCONFIG=/etc/sysconfig/docker
-       $ cat <<EOF | sudo tee /etc/systemd/system/docker.service.d/kata-containers.conf
+       # Add kata-runtime to the list of available runtimes, if not already listed
-       [Service]
+       $ grep -qE "^ *DOCKER_OPTS=.+--add-runtime[= ] *kata-runtime" $DOCKER_SYSCONFIG || sudo -E sed -i -E "s|^( *DOCKER_OPTS=.+)\" *$|\1 --add-runtime kata-runtime=/usr/bin/kata-runtime\"|g" $DOCKER_SYSCONFIG
-       ExecStart=
+       # If a current default runtime is specified, overwrite it with kata-runtime
-       ExecStart=/usr/bin/dockerd -D --add-runtime kata-runtime=/usr/bin/kata-runtime --default-runtime=kata-runtime
+       $ sudo -E sed -i -E "s|^( *DOCKER_OPTS=.+--default-runtime[= ] *)[^ \"]+(.*\"$)|\1kata-runtime\2|g" $DOCKER_SYSCONFIG
-       EOF
+       # Add kata-runtime as default runtime, if no default runtime is specified
+       $ grep -qE "^ *DOCKER_OPTS=.+--default-runtime" $DOCKER_SYSCONFIG || sudo -E sed -i -E "s|^( *DOCKER_OPTS=.+)(\"$)|\1 --default-runtime=kata-runtime\2|g" $DOCKER_SYSCONFIG
        ```
 
    2. Docker `daemon.json`

install/opensuse-installation-guide.md

@@ -1,4 +1,4 @@
-# Install Kata Containers on openSUSE Leap/Tumbleweed
+# Install Kata Containers on openSUSE
 
 1. Install the Kata Containers components with the following commands:
 
@@ -18,6 +18,5 @@
    ```
 
 2. Decide which container manager to use and select the corresponding link that follows:
-
    - [Docker](docker/opensuse-docker-install.md)
-   - [Kubernetes](https://github.com/kata-containers/documentation/blob/master/Developer-Guide.md#run-kata-containers-with-kubernetes)
+   - [Kubernetes](../Developer-Guide.md#run-kata-containers-with-kubernetes)

install/opensuse-leap-installation-guide.md

@@ -1,6 +1,7 @@
 # Install Kata Containers on openSUSE Leap
 
-Follow the instructions in the generic [openSUSE install guide](opensuse-installation-guide.md).
+1. Install Kata Containers on openSUSE by following the instructions in the
+[openSUSE install guide](opensuse-installation-guide.md).
 <!--
 You can ignore the content of this comment.
 (test code run by test-install-docs.sh to validate code blocks this document)
@@ -12,3 +13,7 @@ https://raw.githubusercontent.com/kata-containers/documentation/master/install/o
 Please download this file and run kata-doc-to-script.sh again."
 ```
 -->
+
+2. Decide which container manager to use and select the corresponding link that follows:
+   - [Docker](docker/opensuse-leap-docker-install.md)
+   - [Kubernetes](../Developer-Guide.md#run-kata-containers-with-kubernetes)

install/opensuse-tumbleweed-installation-guide.md

@@ -1,6 +1,7 @@
 # Install Kata Containers on openSUSE Tumbleweed
 
-Follow the instructions in the generic [openSUSE install guide](opensuse-installation-guide.md).
+1. Install Kata Containers on openSUSE by following the instructions in the
+[openSUSE install guide](opensuse-installation-guide.md).
 <!--
 You can ignore the content of this comment.
 (test code run by test-install-docs.sh to validate code blocks this document)
@@ -12,3 +13,7 @@ https://raw.githubusercontent.com/kata-containers/documentation/master/install/o
 Please download this file and run kata-doc-to-script.sh again."
 ```
 -->
+
+2. Decide which container manager to use and select the corresponding link that follows:
+   - [Docker](docker/opensuse-tumbleweed-docker-install.md)
+   - [Kubernetes](../Developer-Guide.md#run-kata-containers-with-kubernetes)