Next we will need to SSH into all four of the instances and install the Kubernetes components.

As root, perform the following steps on all four instances:

1. Update packages and install the apt-transport-https package so we can download from sources   that use HTTPS:

   $ apt-get update 
   $ apt-get install -y apt-transport-https

2. Install the Google Cloud public key:

   $ curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg |
   apt-key add -    

3. Next, create a source list for the Kubernetes package downloads with your favorite editor:

   $ vi /etc/apt/sources.list.d/kubernetes.list

4. Use the following as contents for this file and save:

   deb http://apt.kubernetes.io/ kubernetes-xenial main

Listing 1-1. /etc/apt/sources.list.d/kubernetes.list

5. Update your sources once more:

   $ apt-get update

6. Install Docker and the core Kubernetes components:

   $ apt-get install -y docker.io 
   $ apt-get install -y kubelet kubeadm kubectl kubernetes-cni