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# Live update example
This example demonstrates the usage of Kubernetes to perform a live update on a running group of pods.

### Step Zero: Prerequisites

This example assumes that you have forked the repository and [turned up a Kubernetes cluster](https://github.com/GoogleCloudPlatform/kubernetes-new#setup):

    $ cd kubernetes
    $ hack/dev-build-and-up.sh
    $ hack/build-go.sh

This example also assumes that you have [Docker](http://docker.io) installed on your local machine.

It also assumes that ```$DOCKER_USER``` is set to your docker user id.

You may need to open the firewall for port 8080 using the [console][cloud-console] or the `gcutil` tool. The following command will allow traffic from any source to instances tagged `kubernetes-minion`:

```shell
$ gcutil addfirewall --allowed=tcp:8080 --target_tags=kubernetes-minion kubernetes-minion-8080
```

### Step One: Build the image

    $ cd kubernetes/examples/update-demo/image
    $ docker build -t $DOCKER_USER/data .
    $ docker push $DOCKER_USER/data

### Step Two: Run the controller
Now we will turn up two replicas of that image.  They all serve on port 8080, mapped to internal port 80

    $ cd kubernetes
    $ cluster/kubecfg.sh -p 8080:80 run $DOCKER_USER/data 2 dataController

### Step Three: Turn up the UX for the demo
In a different terminal:

    $ cd kubernetes
    $ cluster/kubecfg.sh -proxy -www examples/update-demo/local/

Now visit the the [demo website](http://localhost:8001/static/index.html).  You should see two light blue squares with pod IDs and ip addresses.

### Step Four: Try resizing the controller
Now we will increase the number of replicas from two to four:

    $ cd kubernetes
    $ cluster/kubecfg.sh resize dataController 4

If you go back to the [demo website](http://localhost:8001/static/index.html) you should eventually see four boxes, one for each pod.

### Step Five: Update the docker image
We will now update the docker image to serve a different color.

    $ cd kubernetes/examples/update-demo/image
    $ ${EDITOR} data.json

Edit the ```color``` value so that it is a new color.  For example:
```js
{
  "color": "#F00"
}
```
Will set the color to red.

Once you are happy with the color, build a new image:

    $ docker build -t $DOCKER_USER/data .
    $ docker push $DOCKER_USER/data

### Step Six: Roll the update out to your servers
We will now update the servers that are running out in your cluster.

    $ cd kubernetes
    $ cluster/kubecfg.sh -u=30s rollingupdate dataController

Watch the UX, it will update one pod every 30 seconds until all of the pods have the new color.

[cloud-console]: https://console.developer.google.com