Kubecraft

A simple Minecraft Docker client, to visualize and manage Kubernetes pods.

YouTube video

How to run Kubecraft

1. Install Minecraft: minecraft.net

   The Minecraft client hasn't been modified, just get the official release.

2. Pull or build Kubecraft image:

   docker pull stevesloka/kubecraft
   

   or

   git clone [email protected]:stevesloka/kubecraft.git
   cd kubecraft && go/src/kubeproxy/make
   docker build -t stevesloka/kubecraft .
   

3. Run Kubecraft container:

   docker run -t -d -i -p 25565:25565 \
   --name kubecraft \
   -e KUBE_CFG_FILE=/etc/kubeconfig \
   -v ~/.kube/config:/etc/kubeconfig \
   stevesloka/kubecraft
   

   Copying kubeconfig file to enable k8s api server

   The default port for a Minecraft server is 25565, if you prefer a different one: -p <port>:25565

4. Open Minecraft > Multiplayer > Add Server

   The server address is the IP of Docker host. No need to specify a port if you used the default one.

   If you're using Docker Machine: docker-machine ip <machine_name> or if using the Docker beta just use localhost

5. Join Server!

   You should see at least one container in your world, which is the one hosting your Kubecraft server.

   You can start, stop and remove containers interacting with levers and buttons. Kubectl commands are also supported directly via Minecraft's chat window, which is displayed by pressing the T key (default) or / key.

A command always starts with a /.

If you open the prompt using the / key, it will be prefilled with a / character, but if you open it with the T key, it will not be prefilled and you will have to type a / yourself before typing your kubectl command.

example: /kubectl scale deployments my-nginx --replicas=2.

How it works

The Minecraft client itself remains unmodified. All operations are done server side.

The Minecraft server we use is http://cuberite.org. A custom Minecraft compatible game server written in C++. github repo

This server accepts plugins, scripts written in Lua. So we did one for Docker. (world/Plugins/Docker)

Unfortunately, there's no nice API to communicate with these plugins. But there's a webadmin, and plugins can be responsible for "webtabs".

Plugin:AddWebTab("Docker",HandleRequest_Docker)

Basically it means the plugin can catch POST requests sent to http://127.0.0.1:8080/webadmin/Docker/Docker.

Kubeproxy

Events from the Kubernetes API are transmitted to the Lua plugin by a small daemon (written in Go). (go/src/kubeproxy)

func MCServerRequest(data url.Values, client *http.Client) {
	req, _ := http.NewRequest("POST", "http://127.0.0.1:8080/webadmin/Docker/Docker", strings.NewReader(data.Encode()))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.SetBasicAuth("admin", "admin")
	client.Do(req)
}

The kubeproxy binary can also be executed with parameters from the Lua plugin, to send requests to the daemon:

function PlayerJoined(Player)
	-- refresh containers
	r = os.execute("goproxy containers")
end

Thanks!

Thanks to the awesome folks who built Dockercraft! Please go check it out as well: https://github.com/docker/dockercraft

If you're interested about Dockercraft's design, discussions happen in that issue. Also, we're using Magicavoxel to do these nice prototypes:

You can find our Magicavoxel patterns in that folder.

To get fresh news, follow their Twitter account: @dockercraft.