# OpenStack Zun DevStack working with Kata Containers
## Introduction

This guide describes how to get Kata Containers to work with OpenStack Zun
using DevStack on Ubuntu 16.04. Running DevStack with this guide will setup
Docker and Clear Containers 2.0, which you replace with Kata Containers.
Currently, the instructions are based on the following links:

- https://docs.openstack.org/zun/latest/contributor/quickstart.html

- https://docs.openstack.org/zun/latest/admin/clear-containers.html

## Install Git to use with DevStack

```sh
$ sudo apt install git
```

## Setup OpenStack DevStack
The following commands will sync DevStack from GitHub, create your
`local.conf` file, assign your host IP to this file, enable Clear
Containers, start DevStack, and set the environment variables to use
`zun` on the command line.

```sh
$ sudo mkdir -p /opt/stack
$ sudo chown $USER /opt/stack
$ git clone https://github.com/openstack-dev/devstack /opt/stack/devstack
$ HOST_IP="$(ip addr | grep 'state UP' -A2 | tail -n1 | awk '{print $2}' | cut -f1 -d'/')"
$ git clone https://github.com/openstack/zun /opt/stack/zun
$ cat /opt/stack/zun/devstack/local.conf.sample \
$     | sed "s/HOST_IP=.*/HOST_IP=$HOST_IP/" \
$     > /opt/stack/devstack/local.conf
$ sed -i "s/KURYR_CAPABILITY_SCOPE=.*/KURYR_CAPABILITY_SCOPE=local/" /opt/stack/devstack/local.conf
$ echo "ENABLE_CLEAR_CONTAINER=true" >> /opt/stack/devstack/local.conf
$ echo "enable_plugin zun-ui https://git.openstack.org/openstack/zun-ui" >> /opt/stack/devstack/local.conf
$ /opt/stack/devstack/stack.sh
$ source /opt/stack/devstack/openrc admin admin
```

The previous commands start OpenStack DevStack with Zun support. You can test
it using `runc` as shown by the following commands to make sure everything
installed correctly and is working.

```sh
$ zun run --name test cirros ping -c 4 8.8.8.8
$ zun list
$ zun logs test
$ zun delete test
```

## Install Kata Containers

Follow [these instructions](../install/README.md)
to install the Kata Containers components.

## Update Docker with new Kata Containers runtime

The following commands replace the Clear Containers 2.x runtime setup with
DevStack, with Kata Containers:

```sh
$ sudo sed -i 's/"cor"/"kata-runtime"/' /etc/docker/daemon.json
$ sudo sed -i 's/"\/usr\/bin\/cc-oci-runtime"/"\/usr\/bin\/kata-runtime"/' /etc/docker/daemon.json
$ sudo systemctl daemon-reload
$ sudo systemctl restart docker
```

## Test that everything works in both Docker and OpenStack Zun

```sh
$ sudo docker run -ti --runtime kata-runtime busybox sh
$ zun run --name kata --runtime kata-runtime cirros ping -c 4 8.8.8.8
$ zun list
$ zun logs kata
$ zun delete kata
```

## Stop DevStack and clean up system (Optional)

```sh
$ /opt/stack/devstack/unstack.sh
$ /opt/stack/devstack/clean.sh
```

## Restart DevStack and reset CC 2.x runtime to `kata-runtime`

Run the following commands if you already setup Kata Containers and want to
restart DevStack:

```sh
$ /opt/stack/devstack/unstack.sh
$ /opt/stack/devstack/clean.sh
$ /opt/stack/devstack/stack.sh
$ source /opt/stack/devstack/openrc admin admin
$ sudo sed -i 's/"cor"/"kata-runtime"/' /etc/docker/daemon.json
$ sudo sed -i 's/"\/usr\/bin\/cc-oci-runtime"/"\/usr\/bin\/kata-runtime"/' /etc/docker/daemon.json
$ sudo systemctl daemon-reload
$ sudo systemctl restart docker
```

![Kata Zun image 1](./images/kata-zun1.png)

Figure 1: Create a BusyBox container image

![Kata Zun image 2](./images/kata-zun2.png)

Figure 2: Select `kata-runtime` to use

![Kata Zun image 3](./images/kata-zun3.png)

Figure 3: Two BusyBox containers successfully launched

![Kata Zun image 4](./images/kata-zun4.png)

Figure 4: Test connectivity between Kata Containers

![Kata Zun image 5](./images/kata-zun5.png)

Figure 5: CLI for Zun