Allow specifying optional Kubernetes version to deploy

This will be used for kubernetes admin labs, to upgrade
an existing cluster. In order to be able to perform an
upgrade, we need a cluster running an older version.

prepare-vms/lib/commands.sh

@@ -116,7 +116,7 @@ _cmd_kubebins() {
         | sudo tar --strip-components=1 --wildcards -zx '*/etcd' '*/etcdctl'
     fi
     if ! [ -x hyperkube ]; then
-        curl -L https://dl.k8s.io/v1.14.0/kubernetes-server-linux-amd64.tar.gz \
+        curl -L https://dl.k8s.io/v1.14.1/kubernetes-server-linux-amd64.tar.gz \
         | sudo tar --strip-components=3 -zx kubernetes/server/bin/hyperkube
     fi
     if ! [ -x kubelet ]; then
@@ -139,6 +139,15 @@ _cmd_kube() {
     TAG=$1
     need_tag
 
+    KUBEVERSION=$2
+    if [ "$KUBEVERSION" ]; then
+        EXTRA_KUBELET="=$KUBEVERSION-00"
+        EXTRA_KUBEADM="--kubernetes-version=v$KUBEVERSION"
+    else
+        EXTRA_KUBELET=""
+        EXTRA_KUBEADM=""
+    fi
+
     # Install packages
     pssh --timeout 200 "
     curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg |
@@ -147,14 +156,14 @@ _cmd_kube() {
     sudo tee /etc/apt/sources.list.d/kubernetes.list"
     pssh --timeout 200 "
     sudo apt-get update -q &&
-    sudo apt-get install -qy kubelet kubeadm kubectl &&
+    sudo apt-get install -qy kubelet$EXTRA_KUBELET kubeadm kubectl &&
     kubectl completion bash | sudo tee /etc/bash_completion.d/kubectl"
 
     # Initialize kube master
     pssh --timeout 200 "
     if grep -q node1 /tmp/node && [ ! -f /etc/kubernetes/admin.conf ]; then
         kubeadm token generate > /tmp/token &&
-	sudo kubeadm init --token \$(cat /tmp/token) --apiserver-cert-extra-sans \$(cat /tmp/ipv4)
+	sudo kubeadm init $EXTRA_KUBEADM --token \$(cat /tmp/token) --apiserver-cert-extra-sans \$(cat /tmp/ipv4)
     fi"
 
     # Put kubeconfig in ubuntu's and docker's accounts