Add a Docker multi-node setup.

docs/getting-started-guides/docker-multinode/worker.md

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+## Adding a Kubernetes worker node via Docker.
+
+These instructions are very similar to the master set-up above, but they are duplicated for clarity.
+You need to repeat these instructions for each node you want to join the cluster.
+We will assume that the IP address of this node is ```${NODE_IP}``` and you have the IP address of the master in ```${MASTER_IP}``` that you created in the [master instructions](master.md).
+
+For each worker node, there are three steps:
+   * [Set up ```flanneld``` on the worker node](#set-up-flanneld-on-the-worker-node)
+   * [Start kubernetes on the worker node](#start-kubernetes-on-the-worker-node)
+   * [Add the worker to the cluster](#add-the-node-to-the-cluster)
+
+### Set up Flanneld on the worker node
+As before, the Flannel daemon is going to provide network connectivity.
+
+#### Set up a bootstrap docker:
+As previously, we need a second instance of the Docker daemon running to bootstrap the flannel networking.
+
+Run:
+```sh
+sudo sh -c 'docker -d -H unix:///var/run/docker-bootstrap.sock -p /var/run/docker-bootstrap.pid --iptables=false --ip-masq=false --bridge=none --graph=/var/lib/docker-bootstrap 2> /var/log/docker-bootstrap.log 1> /dev/null &'
+```
+
+_Important Note_:
+If you are running this on a long running system, rather than experimenting, you should run the bootstrap Docker instance under something like SysV init, upstart or systemd so that it is restarted
+across reboots and failures.
+
+#### Bring down Docker
+To re-configure Docker to use flannel, we need to take docker down, run flannel and then restart Docker.
+
+Turning down Docker is system dependent, it may be:
+
+```sh
+sudo /etc/init.d/docker stop
+```
+
+or
+
+```sh
+sudo systemctl stop docker
+```
+
+or it may be something else.
+
+#### Run flannel
+
+Now run flanneld itself, this call is slightly different from the above, since we point it at the etcd instance on the master.
+```sh
+sudo docker -H unix:///var/run/docker-bootstrap.sock run -d --net=host --privileged -v /dev/net:/dev/net quay.io/coreos/flannel:0.3.0 /opt/bin/flanneld --etcd-endpoints=http://${MASTER_IP}:4001
+```
+
+The previous command should have printed a really long hash, copy this hash.
+
+Now get the subnet settings from flannel:
+```
+sudo docker -H unix:///var/run/docker-bootstrap.sock exec <really-long-hash-from-above-here> cat /run/flannel/subnet.env
+```
+
+
+#### Edit the docker configuration
+You now need to edit the docker configuration to activate new flags.  Again, this is system specific.
+
+This may be in ```/etc/default/docker``` or ```/etc/systemd/service/docker.service``` or it may be elsewhere.
+
+Regardless, you need to add the following to the docker comamnd line:
+```sh
+--bip=${FLANNEL_SUBNET} --mtu=${FLANNEL_MTU}
+```
+
+#### Remove the existing Docker bridge
+Docker creates a bridge named ```docker0``` by default.  You need to remove this:
+
+```sh
+sudo /sbin/ifconfig docker0 down
+sudo brctl delbr docker0
+```
+
+You may need to install the ```bridge-utils``` package for the ```brctl``` binary.
+
+#### Restart Docker
+Again this is system dependent, it may be:
+
+```sh
+sudo /etc/init.d/docker start
+```
+
+it may be:
+```sh
+systemctl start docker
+```
+
+### Start Kubernetes on the worker node
+#### Run the kubelet
+Again this is similar to the above, but the ```--api_servers``` now points to the master we set up in the beginning.
+
+```sh
+sudo docker run --net=host -d -v /var/run/docker.sock:/var/run/docker.sock  gcr.io/google_containers/hyperkube:v0.14.1 /hyperkube kubelet --api_servers=http://${MASTER_IP}:8080 --v=2 --address=0.0.0.0 --enable_server --hostname_override=$(hostname -i)
+```
+
+#### Run the service proxy
+The service proxy provides load-balancing between groups of containers defined by Kubernetes ```Services```
+
+```sh
+sudo docker run -d --net=host --privileged gcr.io/google_containers/hyperkube:v0.14.1 /hyperkube proxy --master=http://${MASTER_IP}:8080 --v=2
+```
+
+
+### Add the node to the cluster
+
+On the master you created above, create a file named ```node.yaml``` make it's contents:
+
+```yaml
+apiVersion: v1beta1
+externalID: ${NODE_IP}
+hostIP: ${NODE_IP}
+id: ${NODE_IP}
+kind: Node
+resources:
+  capacity:
+    # Adjust these to match your node
+    cpu: "1"
+    memory: 3892043776
+```
+
+Make the API call to add the node, you should do this on the master node that you created above.  Otherwise you need to add ```-s=http://${MASTER_IP}:8080``` to point ```kubectl``` at the master.
+
+```sh
+./kubectl create -f node.yaml
+```
+
+### Next steps
+
+Move on to [testing your cluster](testing.md) or [add another node](#adding-a-kubernetes-worker-node-via-docker)