Refactor Vagrant configuration.

Vagrantfile

@@ -1,5 +1,3 @@
-VAGRANTFILE_API_VERSION = "2"
-
 require File.expand_path(File.join(File.dirname(__FILE__), 'vagrant-common.rb'))
 
 vm_ip = "172.16.0.3" # arbitrary private IP
@@ -19,17 +17,20 @@ pkgs = %w(
 
 Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
 
-  config.vm.box = "ubuntu/wily64"
+  config.vm.box = VAGRANT_IMAGE
 
   config.vm.network "private_network", ip: vm_ip
   config.vm.provider :virtualbox do |vb|
     vb.memory = 2048
-    vb.customize ["modifyvm", :id, "--natdnshostresolver1", "off"]
-    vb.customize ["modifyvm", :id, "--natdnsproxy1", "off"]
+    configure_nat_dns(vb)    
   end
 
+  # Disable default Vagrant shared folder, which we don't need:
   config.vm.synced_folder ".", "/vagrant", disabled: true
+  # Keep Weave Net sources' in sync:
   config.vm.synced_folder ".", "/home/vagrant/src/github.com/weaveworks/weave"
+  # Create a convenience symlink to $HOME/src/github.com/weaveworks/weave
+  config.vm.provision :shell, :inline => 'ln -sf ~vagrant/src/github.com/weaveworks/weave ~vagrant/'
 
   # Set SSH keys up to be able to run smoke tests straightaway:
   config.vm.provision "file", source: "~/.vagrant.d/insecure_private_key", destination: "/home/vagrant/src/github.com/weaveworks/weave/test/insecure_private_key"

test/Vagrantfile

@@ -1,5 +1,3 @@
-VAGRANTFILE_API_VERSION = "2"
-
 # Necessary because the switch disabling unwanted insecure key
 # replacement in Vagrant 1.7+ is not accepted by earlier versions
 Vagrant.require_version ">= 1.7.0"
@@ -14,11 +12,12 @@ require File.expand_path(File.join(File.dirname(__FILE__), '..', 'vagrant-common
 def configure_docker(host, hostname, ip)
   pkgs = %w(docker-engine ethtool)
 
-  host.vm.box = "ubuntu/wily64"
+  host.vm.box = VAGRANT_IMAGE
 
   host.vm.provision :shell, :inline => "hostnamectl set-hostname "+hostname
   host.vm.network "private_network", ip: ip
 
+  # Disable default Vagrant shared folder, which we don't need:
   host.vm.synced_folder ".", "/vagrant", disabled: true
 
   host.vm.provision :shell, :inline => "sudo apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D"
@@ -38,9 +37,8 @@ end
 Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
 
   config.vm.provider :virtualbox do |vb|
-    vb.customize ["modifyvm", :id, "--natdnshostresolver1", "off"]
-    vb.customize ["modifyvm", :id, "--natdnsproxy1", "off"]
     vb.memory = 384
+    configure_nat_dns(vb)
   end
 
   # Disable Vagrant 1.7 per host insecure key replacement

vagrant-common.rb

@@ -1,11 +1,23 @@
-$go_regexp = /FROM golang:(\S*).*?/
-$dockerfile_path = File.expand_path(File.join(File.dirname(__FILE__), 'build', 'Dockerfile'))
-$go_version = File.readlines($dockerfile_path).first { |line| line.match($go_regexp) }.match($go_regexp).captures.first
-if $go_version.nil?
-  raise ArgumentError.new("Failed to read Go version from Dockerfile.")
+VAGRANT_IMAGE = 'ubuntu/wily64'
+VAGRANTFILE_API_VERSION = '2'
+
+def get_go_version_from_build_dockerfile()
+  go_regexp = /FROM golang:(\S*).*?/
+  dockerfile_path = File.expand_path(File.join(File.dirname(__FILE__), 'build', 'Dockerfile'))
+  go_version = File.readlines(dockerfile_path).first { |line| line.match(go_regexp) }.match(go_regexp).captures.first
+  if go_version.nil?
+    raise ArgumentError.new("Failed to read Go version from Dockerfile.")
+  end
+  go_version
 end
 
-$go_path = "/usr/local/go/bin"
+GO_BINARY_PATH = '/usr/local/go/bin'
+GO_VERSION = get_go_version_from_build_dockerfile()
+
+def configure_nat_dns(vb)
+  vb.customize ["modifyvm", :id, "--natdnshostresolver1", "off"]
+  vb.customize ["modifyvm", :id, "--natdnsproxy1", "off"]
+end
 
 def install_packages(vm, pkgs)
   vm.provision :shell, :inline => <<SCRIPT
@@ -28,10 +40,10 @@ end
 
 def install_go_toochain(vm)
   vm.provision :shell, :inline => <<SCRIPT
-curl -s https://storage.googleapis.com/golang/go#{$go_version}.linux-amd64.tar.gz \
+curl -s https://storage.googleapis.com/golang/go#{GO_VERSION}.linux-amd64.tar.gz \
   | tar xz -C /usr/local
-#{$go_path}/go clean -i net
-#{$go_path}/go install -tags netgo std
+#{GO_BINARY_PATH}/go clean -i net
+#{GO_BINARY_PATH}/go install -tags netgo std
 SCRIPT
 end
 
@@ -39,7 +51,7 @@ def tweak_user_env(vm)
   script = <<SCRIPT
 echo 'export GOPATH="${HOME}"' \
   >> ~vagrant/.profile
-echo 'export PATH="${HOME}/bin:#{$go_path}:${PATH}"' \
+echo 'export PATH="${HOME}/bin:#{GO_BINARY_PATH}:${PATH}"' \
   >> ~vagrant/.profile
 ln -sf ~vagrant/src/github.com/weaveworks/weave ~vagrant/
 sudo chown -R vagrant:vagrant ~vagrant/src