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# Kubernetes cluster example with Ubuntu

You can easily build a cluster using kubeadm and kubectl on Ubuntu 18.04.

### Perform these steps on **all the machines** that will be part of your cluster.

First, have Docker installed:
```
sudo apt-get install -y docker.io
```

Then install the kubeadm toolbox:
```
sudo apt-get update && sudo apt-get install -y apt-transport-https curl
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl
```

Swap must be disabled for kubelet to run:
```
sudo swapoff -a
```

### Only on the machine designated as **master node**:

Select the IP address to broadcast the Kubernetes API. With ``` ifconfig ``` you can check the IPs of the network interfaces on your master node (with a public IP you can expose the cluster to the internet).

Then run the following line substituting ```<IP-address>``` with your IP.
```
sudo kubeadm init --apiserver-advertise-address=<IP-address>
```
When it finishes executing, you will find a result similar to this:
```
Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube
  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
  sudo chown $(id -u):$(id -g) $HOME/.kube/config

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join <IP-address>:6443 --token 29am26.3fw2znktwbbff0we \
    --discovery-token-ca-cert-hash sha256:eb32f7f58ae6907f26ed5c075ecd4ef6756d832b6c358fd4b2f408e52d18a369
```
Now kubeadm set up a cluster with just the master node. Run those 3 instructions to copy the admin.conf file, to connect kubectl to the new cluster.

Then you can checkout your nodes with:
```
kubectl get nodes

NAME          STATUS     ROLES    AGE     VERSION
master-node   NotReady   master   7m25s   v1.17.0
```
The node will stay in the **NotReady** status until you apply Pod Networking. With Weave Net run:
```
kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"
```
After a minute the node will be **Ready**. Check the [Weave Net addon](https://www.weave.works/docs/net/latest/kubernetes/kube-addon/#install) to know more.

Now you're ready to let other machines join. Use the join command kubeadm printed earlier on them.
```
kubeadm join <IP-address>:6443 --token 29am26.3fw2znktwbbff0we \
    --discovery-token-ca-cert-hash sha256:eb32f7f58ae6907f26ed5c075ecd4ef6756d832b6c358fd4b2f408e52d18a369

```
After a node joined give it time to get in the Ready status, then you can check that everything is
running with: ```kubectl get all -A```.

Now you have a running cluster with a master node and one or more worker nodes.

Before deploying OpenWhisk, you have to set up [Dynamic Volume
Provision](https://kubernetes.io/docs/concepts/storage/dynamic-provisioning/), as the [technical
requirements](docs/k8s-technical-requirements.md) specify. For example, you can dynamically provision NFS persistent volumes, setting up an nfs server, a client provisioner and a storage class. Now you're ready to deploy openwhisk with [Helm](##Helm).