Kubernetes

The Kubernetes example provisions a 3 node Kubernetes v1.4.6 cluster with one controller, two workers, and TLS authentication. An etcd cluster backs Kubernetes and coordinates CoreOS auto-updates (enabled for disk installs).

Requirements

Ensure that you've gone through the bootcfg with rkt or bootcfg with docker guide and understand the basics. In particular, you should be able to:

Use rkt or Docker to start bootcfg
Create a network boot environment with coreos/dnsmasq
Create the example libvirt client VMs
/etc/hosts entries for node[1-3].example.com (or pass custom names to k8s-certgen)

Examples

The examples statically assign IP addresses to libvirt client VMs created by scripts/libvirt. VMs are setup on the metal0 CNI bridge for rkt or the docker0 bridge for Docker. The examples can be used for physical machines if you update the MAC addresses. See network setup and deployment.

k8s - iPXE boot a Kubernetes cluster
k8s-install - Install a Kubernetes cluster to disk
Lab examples - Lab hardware examples

Assets

Download the CoreOS image assets referenced in the target profile.

./scripts/get-coreos stable 1185.3.0 ./examples/assets

Optionally, add your SSH public key to each machine group definition as shown.

Generate a root CA and Kubernetes TLS assets for components (admin, apiserver, worker) with SANs for node1.example.com, etc.

rm -rf examples/assets/tls
./scripts/tls/k8s-certgen

Note: TLS assets are served to any machines which request them, which requires a trusted network. Alternately, provisioning may be tweaked to require TLS assets be securely copied to each host.

Containers

Use rkt or docker to start bootcfg and mount the desired example resources. Create a network boot environment and power-on your machines. Revisit bootcfg with rkt or bootcfg with Docker for help.

Client machines should boot and provision themselves. Local client VMs should network boot CoreOS in about a 1 minute and the Kubernetes API should be available after 3-4 minutes (each node downloads a ~160MB Hyperkube). If you chose k8s-install, notice that machines install CoreOS and then reboot (in libvirt, you must hit "power" again). Time to network boot and provision Kubernetes clusters on physical hardware depends on a number of factors (POST duration, boot device iteration, network speed, etc.).

Verify

Install kubectl on your laptop. Use the generated kubeconfig to access the Kubernetes cluster created on rkt metal0 or docker0.

$ KUBECONFIG=examples/assets/tls/kubeconfig
$ kubectl get nodes
NAME                STATUS    AGE
node1.example.com   Ready     3m
node2.example.com   Ready     3m
node3.example.com   Ready     3m

Get all pods.

$ kubectl get pods --all-namespaces
NAMESPACE     NAME                                        READY     STATUS    RESTARTS   AGE
kube-system   heapster-v1.2.0-4088228293-k3yn8            2/2       Running   0          3m
kube-system   kube-apiserver-node1.example.com            1/1       Running   0          4m
kube-system   kube-controller-manager-node1.example.com   1/1       Running   0          3m
kube-system   kube-dns-v19-l2u8r                          3/3       Running   0          4m
kube-system   kube-proxy-node1.example.com                1/1       Running   0          3m
kube-system   kube-proxy-node2.example.com                1/1       Running   0          3m
kube-system   kube-proxy-node3.example.com                1/1       Running   0          3m
kube-system   kube-scheduler-node1.example.com            1/1       Running   0          3m
kube-system   kubernetes-dashboard-v1.4.1-0iy07           1/1       Running   0          4m

Kubernetes Dashboard

Access the Kubernetes Dashboard with kubeconfig credentials by port forwarding to the dashboard pod.

$ kubectl port-forward kubernetes-dashboard-v1.4.1-SOME-ID 9090 -n=kube-system
Forwarding from 127.0.0.1:9090 -> 9090

Then visit http://127.0.0.1:9090.

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