Update Docker install script and recommended version

main.tf

@@ -29,6 +29,7 @@ variable "worker_plan" {
   default     = "t1.small.x86"
 }
 
+// General template used to install docker on Ubuntu 16.04
 data "template_file" "install_docker" {
   template = "${file("${path.module}/templates/install-docker.sh.tpl")}"
 

templates/install-docker.sh.tpl

@@ -5,10 +5,48 @@ echo "[----- Begin install-docker.sh ----]"
 
 echo "Installing Docker ${docker_version}"
 
-apt-get update
-apt-get install -y apt-transport-https ca-certificates curl software-properties-common
+# Based on from https://kubernetes.io/docs/setup/cri/#docker
+
+# Install Docker CE
+## Set up the repository:
+### Install packages to allow apt to use a repository over HTTPS
+apt-get update \
+  && apt-get install -y \
+  apt-transport-https \
+  ca-certificates \
+  curl \
+  software-properties-common
+
+### Add Docker’s official GPG key
 curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -
-add-apt-repository "deb https://download.docker.com/linux/$(. /etc/os-release; echo "$ID") $(lsb_release -cs) stable"
-apt-get update && apt-get install -y docker-ce=$(apt-cache madison docker-ce | grep ${docker_version} | head -1 | awk '{print $3}')
+
+### Add Docker apt repository
+add-apt-repository \
+  "deb [arch=amd64] https://download.docker.com/linux/$(. /etc/os-release; echo "$ID") \
+  $(lsb_release -cs) \
+  stable"
+
+## Install Docker CE
+apt-get update \
+  && apt-get install -y \
+  docker-ce=$(apt-cache madison docker-ce | grep ${docker_version} | head -1 | awk '{print $3}')
+
+# Setup daemon
+cat > /etc/docker/daemon.json <<EOF
+{
+  "exec-opts": ["native.cgroupdriver=systemd"],
+  "log-driver": "json-file",
+  "log-opts": {
+    "max-size": "100m"
+  },
+  "storage-driver": "overlay2"
+}
+EOF
+
+mkdir -p /etc/systemd/system/docker.service.d
+
+# Restart docker
+systemctl daemon-reload
+systemctl restart docker
 
 echo "[----- install-docker.sh Complete ------]"

templates/setup-kubeadm.sh.tpl

@@ -19,7 +19,7 @@ nodeRegistration:
     value: "master"
     effect: "NoSchedule"
   kubeletExtraArgs:
-    cgroup-driver: "cgroupfs"
+    cgroup-driver: "systemd"
 ---
 apiVersion: kubeadm.k8s.io/v1beta1
 kind: ClusterConfiguration

variables.tf

@@ -3,7 +3,7 @@ variable "auth_token" {
 }
 
 variable "docker_version" {
-  default = "18.09"
+  default = "18.06.2"
 }
 
 variable "kubernetes_version" {