website/v1.1/docs/getting-started-guides/docker-multinode/master.md

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docwithnav	Installing a Kubernetes Master Node via Docker

Installing a Kubernetes Master Node via Docker

We'll begin by setting up the master node. For the purposes of illustration, we'll assume that the IP of this machine is ${MASTER_IP}

There are two main phases to installing the master:

• Setting up flanneld and etcd
• Starting the Kubernetes master components

Setting up flanneld and etcd

Note: There is a bug in Docker 1.7.0 that prevents this from working correctly. Please install Docker 1.6.2 or Docker 1.7.1.

Setup Docker-Bootstrap

We're going to use flannel to set up networking between Docker daemons. Flannel itself (and etcd on which it relies) will run inside of Docker containers themselves. To achieve this, we need a separate "bootstrap" instance of the Docker daemon. This daemon will be started with --iptables=false so that it can only run containers with --net=host. That's sufficient to bootstrap our system.

Run:

{% highlight sh %} {% raw %} 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 &' {% endraw %} {% endhighlight %}

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.

Startup etcd for flannel and the API server to use

Run:

{% highlight sh %} {% raw %} sudo docker -H unix:///var/run/docker-bootstrap.sock run --net=host -d gcr.io/google_containers/etcd:2.0.12 /usr/local/bin/etcd --addr=127.0.0.1:4001 --bind-addr=0.0.0.0:4001 --data-dir=/var/etcd/data {% endraw %} {% endhighlight %}

Next, you need to set a CIDR range for flannel. This CIDR should be chosen to be non-overlapping with any existing network you are using:

{% highlight sh %} {% raw %} sudo docker -H unix:///var/run/docker-bootstrap.sock run --net=host gcr.io/google_containers/etcd:2.0.12 etcdctl set /coreos.com/network/config '{ "Network": "10.1.0.0/16" }' {% endraw %} {% endhighlight %}

Set up Flannel on the master node

Flannel is a network abstraction layer build by CoreOS, we will use it to provide simplified networking between our Pods of containers.

Flannel re-configures the bridge that Docker uses for networking. As a result we need to stop Docker, reconfigure its networking, and then restart Docker.

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:

{% highlight sh %} {% raw %} sudo /etc/init.d/docker stop {% endraw %} {% endhighlight %}

or

{% highlight sh %} {% raw %} sudo systemctl stop docker {% endraw %} {% endhighlight %}

or it may be something else.

Run flannel

Now run flanneld itself:

{% highlight sh %} {% raw %} sudo docker -H unix:///var/run/docker-bootstrap.sock run -d --net=host --privileged -v /dev/net:/dev/net quay.io/coreos/flannel:0.5.0 {% endraw %} {% endhighlight %}

The previous command should have printed a really long hash, copy this hash.

Now get the subnet settings from flannel:

{% highlight sh %} {% raw %} sudo docker -H unix:///var/run/docker-bootstrap.sock exec cat /run/flannel/subnet.env {% endraw %} {% endhighlight %}

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 command line:

{% highlight sh %} {% raw %} --bip=${FLANNEL_SUBNET} --mtu=${FLANNEL_MTU} {% endraw %} {% endhighlight %}

Remove the existing Docker bridge

Docker creates a bridge named docker0 by default. You need to remove this:

{% highlight sh %} {% raw %} sudo /sbin/ifconfig docker0 down sudo brctl delbr docker0 {% endraw %} {% endhighlight %}

You may need to install the bridge-utils package for the brctl binary.

Restart Docker

Again this is system dependent, it may be:

{% highlight sh %} {% raw %} sudo /etc/init.d/docker start {% endraw %} {% endhighlight %}

it may be:

{% highlight sh %} {% raw %} systemctl start docker {% endraw %} {% endhighlight %}

Starting the Kubernetes Master

Ok, now that your networking is set up, you can startup Kubernetes, this is the same as the single-node case, we will use the "main" instance of the Docker daemon for the Kubernetes components.

{% highlight sh %} {% raw %} sudo docker run
--volume=/:/rootfs:ro
--volume=/sys:/sys:ro
--volume=/dev:/dev
--volume=/var/lib/docker/:/var/lib/docker:rw
--volume=/var/lib/kubelet/:/var/lib/kubelet:rw
--volume=/var/run:/var/run:rw
--net=host
--privileged=true
--pid=host \ -d
gcr.io/google_containers/hyperkube:v1.0.1 /hyperkube kubelet --api-servers=http://localhost:8080 --v=2 --address=0.0.0.0 --enable-server --hostname-override=127.0.0.1 --config=/etc/kubernetes/manifests-multi --cluster-dns=10.0.0.10 --cluster-domain=cluster.local {% endraw %} {% endhighlight %}

Note that --cluster-dns and --cluster-domain is used to deploy dns, feel free to discard them if dns is not needed.

Also run the service proxy

{% highlight sh %} {% raw %} sudo docker run -d --net=host --privileged gcr.io/google_containers/hyperkube:v1.0.1 /hyperkube proxy --master=http://127.0.0.1:8080 --v=2 {% endraw %} {% endhighlight %}

Test it out

At this point, you should have a functioning 1-node cluster. Let's test it out!

Download the kubectl binary and make it available by editing your PATH ENV. (OS X) (linux)

List the nodes

{% highlight sh %} {% raw %} kubectl get nodes {% endraw %} {% endhighlight %}

This should print:

{% highlight console %} {% raw %} NAME LABELS STATUS 127.0.0.1 kubernetes.io/hostname=127.0.0.1 Ready {% endraw %} {% endhighlight %}

If the status of the node is NotReady or Unknown please check that all of the containers you created are successfully running. If all else fails, ask questions on Slack.

Next steps

Move on to adding one or more workers or deploy a dns