Add root example README. Fix colocated cluster example.

Author: josh-padnick

_docs/architecture-colocated.png

@@ -32,10 +32,10 @@ https://github.com/hashicorp/terraform-google-nomad/tree/master/examples/nomad-c
 1. Make sure your local environment is authenticated to Google Cloud.
 1. Open `variables.tf` and fill in any variables that don't have a default, including putting your Goolge Image ID into
    the `vault_source_image` and `consul_server_source_image` variables.
-1. Run `terraform get`.
+1. Run `terraform init`.
 1. Run `terraform plan`.
 1. If the plan looks good, run `terraform apply`.
-1. Run the [nomad-examples-helper.sh script](
+1. From the same directoy where you ran `terraform apply`, run the [nomad-examples-helper.sh script](
    https://github.com/hashicorp/terraform-google-nomad/tree/master/examples/nomad-examples-helper/nomad-examples-helper.sh)
    to print out the IP addresses of the Nomad servers and some example commands you can run to interact with the cluster:
    `../nomad-examples-helper/nomad-examples-helper.sh`.

_docs/architecture-nomad-consul-separate.png

@@ -0,0 +1,38 @@
+# Nomad and Consul Co-located Cluster Example
+
+This folder shows an example of Terraform code to deploy a [Nomad](https://www.nomadproject.io/) cluster co-located 
+with a [Consul](https://www.consul.io/) cluster in [Google Cloud](https://cloud.google.com/) (if you want to run Nomad
+and Consul on separate clusters, see the [nomad-consul-separate-cluster example](
+https://github.com/hashicorp/terraform-google-nomad/tree/master/examples/nomad-consul-separate-cluster) instead). The
+cluster consists of two Manged Instance Groups: one with a small number of Nomad and Consul server nodes, which are
+responsible for being part of the [consensus protocol](https://www.nomadproject.io/docs/internals/consensus.html), and
+one with an arbitrary number of Nomad and Consul client nodes, which are used to run jobs:
+
+![Nomad architecture](https://github.com/hashicorp/terraform-google-nomad/master/_docs/architecture-nomad-consul-colocated.png?raw=true)
+
+You will need to create a [Google Image](https://cloud.google.com/compute/docs/images) that has Nomad and Consul
+installed, which you can do using the [nomad-consul-image example](
+https://github.com/hashicorp/terraform-google-nomad/tree/master/examples/nomad-consul-image)).  
+
+For more info on how the Nomad cluster works, check out the [nomad-cluster](
+https://github.com/hashicorp/terraform-google-nomad/tree/master/modules/nomad-cluster) documentation.
+
+## Quick start
+
+To deploy a Nomad Cluster:
+
+1. `git clone` this repo to your computer.
+1. Build a Nomad and Consul Image. See the [nomad-consul-image example](
+https://github.com/hashicorp/terraform-google-nomad/tree/master/examples/nomad-consul-image) documentation for 
+   instructions. Make sure to note down the name of the Image.
+1. Install [Terraform](https://www.terraform.io/).
+1. Make sure your local environment is authenticated to Google Cloud.
+1. Open `variables.tf` and fill in any variables that don't have a default, including putting your Goolge Image ID into
+   the `vault_source_image` and `consul_server_source_image` variables.
+1. Run `terraform init`.
+1. Run `terraform plan`.
+1. If the plan looks good, run `terraform apply`.
+1. From the same directoy where you ran `terraform apply`, run the [nomad-examples-helper.sh script](
+   https://github.com/hashicorp/terraform-google-nomad/tree/master/examples/nomad-examples-helper/nomad-examples-helper.sh)
+   to print out the IP addresses of the Nomad servers and some example commands you can run to interact with the cluster:
+   `../nomad-examples-helper/nomad-examples-helper.sh`.

_docs/architecture.png

@@ -10,5 +10,5 @@ set -e
 exec > >(tee /var/log/user-data.log|logger -t user-data -s 2>/dev/console) 2>&1
 
 # These variables are passed in via Terraform template interplation
-/opt/consul/bin/run-consul --client --cluster-tag-key "${cluster_tag_key}" --cluster-tag-value "${cluster_tag_value}"
+/opt/consul/bin/run-consul --client --cluster-tag-name "${consul_server_cluster_tag_name}"
 /opt/nomad/bin/run-nomad --client

examples/nomad-consul-separate-cluster/README.md

@@ -38,7 +38,7 @@ module "nomad_and_consul_servers" {
   cluster_tag_name = "${var.nomad_consul_server_cluster_name}"
   machine_type = "${var.nomad_consul_server_cluster_machine_type}"
 
-  source_image = "${var.nomad_server_source_image}"
+  source_image = "${var.nomad_consul_server_source_image}"
   startup_script = "${data.template_file.startup_script_nomad_consul_server.rendered}"
 
   # WARNING!

examples/root-example/README.md

@@ -6,23 +6,23 @@ output "gcp_zone" {
   value = "${var.gcp_zone}"
 }
 
-output "nomad_consul_server_cluster_size" {
+output "nomad_server_cluster_size" {
   value = "${var.nomad_consul_server_cluster_size}"
 }
 
 output "nomad_client_cluster_size" {
   value = "${var.nomad_client_cluster_size}"
 }
 
-output "nomad_consul_server_cluster_tag_name" {
+output "nomad_server_cluster_tag_name" {
   value = "${var.nomad_consul_server_cluster_name}"
 }
 
 output "nomad_client_cluster_tag_name" {
   value = "${var.nomad_client_cluster_name}"
 }
 
-output "nomad_consul_server_instance_group_id" {
+output "nomad_server_instance_group_id" {
   value = "${module.nomad_and_consul_servers.instance_group_name}"
 }
 

examples/root-example/startup-script-nomad-client.sh

@@ -21,7 +21,7 @@ variable "nomad_consul_server_cluster_name" {
   description = "The name of the Nomad/Consul Server cluster. All resources will be namespaced by this value. E.g. nomad-server-prod"
 }
 
-variable "nomad_server_source_image" {
+variable "nomad_consul_server_source_image" {
   description = "The Google Image used to launch each node in the Nomad/Consul Server cluster."
 }
 
@@ -56,7 +56,7 @@ variable "nomad_consul_server_cluster_machine_type" {
 
 variable "nomad_client_cluster_size" {
   description = "The number of nodes to have in the Nomad client cluster. This number is arbitrary."
-  default = 2
+  default = 3
 }
 
 variable "nomad_client_machine_type" {