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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

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:

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.

Startup etcd for flannel and the API server to use

Run:

sudo docker -H unix:///var/run/docker-bootstrap.sock run --net=host -d kubernetes/etcd:2.0.5.1 /usr/local/bin/etcd --addr=127.0.0.1:4001 --bind-addr=0.0.0.0:4001 --data-dir=/var/etcd/data

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:

sudo docker -H unix:///var/run/docker-bootstrap.sock run --net=host kubernetes/etcd:2.0.5.1 etcdctl set /coreos.com/network/config '{ "Network": "10.1.0.0/16" }'

Set up Flannel on the master node

Flannel is a network abstraction layer build by CoreOS, we will use it to provide simplfied 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:

sudo /etc/init.d/docker stop

or

sudo systemctl stop docker

or it may be something else.

Run flannel

Now run flanneld itself:

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

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:

--bip=${FLANNEL_SUBNET} --mtu=${FLANNEL_MTU}

Remove the existing Docker bridge

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

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:

sudo /etc/init.d/docker start

it may be:

systemctl start docker

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.

sudo docker run --net=host -d -v /var/run/docker.sock:/var/run/docker.sock  gcr.io/google_containers/hyperkube:v0.14.2 /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

Also run the service proxy

sudo docker run -d --net=host --privileged gcr.io/google_containers/hyperkube:v0.14.2 /hyperkube proxy --master=http://127.0.0.1:8080 --v=2

Test it out

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

Download the kubectl binary (OS X) (linux)

List the nodes

kubectl get nodes

This should print:

NAME        LABELS    STATUS
127.0.0.1   <none>    Ready

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 IRC at #google-containers.

Next steps

Move on to adding one or more workers