Demo: configurable Consul version

- Add CONSUL_DEMO_VERSION env var for specifying Consul version

demo/vagrant-cluster/README.md

@@ -11,7 +11,7 @@ vagrant up
 ```
 
 > NOTE: If you prefer a different Vagrant box, you can set the `DEMO_BOX_NAME`
-> environment variable before Starting Vagrant like this: 
+> environment variable before starting `vagrant` like this: 
 > `DEMO_BOX_NAME="ubuntu/xenial64" vagrant up`
 
 Once it is finished, you should be able to see the following:
@@ -29,7 +29,7 @@ At this point the two nodes are running and you can SSH in to play with them:
 ```
 vagrant ssh n1
 consul version
-Consul v0.7.1
+Consul v0.7.2
 Protocol 2 spoken by default, understands 2 to 3 (agent will automatically use protocol >2 when speaking to compatible agents)
 exit
 ```
@@ -39,12 +39,17 @@ and
 ```
 vagrant ssh n2
 consul version
-Consul v0.7.1
+Consul v0.7.2
 Protocol 2 spoken by default, understands 2 to 3 (agent will automatically use protocol >2 when speaking to compatible agents)
 exit
 ```
 
+> NOTE: This demo will install the latest Consul release version by default,
+> but if you prefer a different version, you can set the `CONSUL_DEMO_VERSION`
+> environment variable before starting `vagrant` like this: 
+> `CONSUL_DEMO_VERSION=0.6.4 vagrant up`
+
 ## Where to Next?
 
-To learn more about starting Consul, joining nodes to a cluster, and
+To learn more about starting Consul, joining nodes into a cluster, and
 interacting with the agent, check out the [Getting Started guide](https://www.consul.io/intro/getting-started/install.html).

demo/vagrant-cluster/Vagrantfile

@@ -1,16 +1,17 @@
 # -*- mode: ruby -*-
 # vi: set ft=ruby :
+
 $script = <<SCRIPT
 
-echo Installing dependencies...
+echo "Installing dependencies ..."
 sudo apt-get update
 sudo apt-get install -y unzip curl
 
-echo Fetching Consul...
+echo "Fetching Consul version ${CONSUL_DEMO_VERSION} ..."
 cd /tmp/
-curl -s https://releases.hashicorp.com/consul/0.7.1/consul_0.7.1_linux_amd64.zip -o consul.zip
+curl -s https://releases.hashicorp.com/consul/${CONSUL_DEMO_VERSION}/consul_${CONSUL_DEMO_VERSION}_linux_amd64.zip -o consul.zip
 
-echo Installing Consul...
+echo "Installing Consul version ${CONSUL_DEMO_VERSION} ..."
 unzip consul.zip
 sudo chmod +x consul
 sudo mv consul /usr/bin/consul
@@ -20,6 +21,9 @@ sudo chmod a+w /etc/consul.d
 
 SCRIPT
 
+# Specify a Consul version
+CONSUL_DEMO_VERSION = ENV['CONSUL_DEMO_VERSION'] || "0.7.2"
+
 # Specify a custom Vagrant box for the demo
 DEMO_BOX_NAME = ENV['DEMO_BOX_NAME'] || "debian/jessie64"
 
@@ -30,7 +34,9 @@ VAGRANTFILE_API_VERSION = "2"
 Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
   config.vm.box = DEMO_BOX_NAME
 
-  config.vm.provision "shell", inline: $script
+  config.vm.provision "shell",
+                          inline: $script,
+                          env: {'CONSUL_DEMO_VERSION' => CONSUL_DEMO_VERSION}
 
   config.vm.define "n1" do |n1|
       n1.vm.hostname = "n1"