core: add Vagrant.latest_version

lib/vagrant/shared_helpers.rb

@@ -1,4 +1,5 @@
 require "pathname"
+require "tempfile"
 
 module Vagrant
   # This is the default endpoint of the Vagrant Cloud in
@@ -25,6 +26,23 @@ module Vagrant
     ENV["VAGRANT_INSTALLER_EMBEDDED_DIR"]
   end
 
+  # Returns the latest version of Vagrant that is available.
+  #
+  # This makes an HTTP call.
+  #
+  # @return [String]
+  def self.latest_version
+    # Lazy-require this so that the overhead of this file is low
+    require "vagrant/util/downloader"
+
+    tf  = Tempfile.new("vagrant")
+    tf.close
+    url = "http://www.vagrantup.com/latest-version.json"
+    Vagrant::Util::Downloader.new(url, tf.path).download!
+    data = JSON.parse(File.read(tf.path))
+    data["version"]
+  end
+
   # This returns whether or not 3rd party plugins should be loaded.
   #
   # @return [Boolean]

plugins/commands/version/command.rb

@@ -1,8 +1,5 @@
 require "json"
 require "optparse"
-require "tempfile"
-
-require "vagrant/util/downloader"
 
 module VagrantPlugins
   module CommandVersion
@@ -25,24 +22,18 @@ module VagrantPlugins
           "vagrant.version_current", version: Vagrant::VERSION))
         @env.ui.machine("version-installed", Vagrant::VERSION)
 
-        # Load the latest installed version to output that.
+        # Load the latest version
-        tf  = Tempfile.new("vagrant")
+        latest = Vagrant.latest_version
-        tf.close
-        url = "http://www.vagrantup.com/latest-version.json"
-        Vagrant::Util::Downloader.new(url, tf.path).download!
-
-        # Parse the JSON result
-        data = JSON.parse(File.read(tf.path))
 
         # Output latest version
         @env.ui.output(I18n.t(
-          "vagrant.version_latest", version: data["version"]))
+          "vagrant.version_latest", version: latest))
-        @env.ui.machine("version-latest", data["version"])
+        @env.ui.machine("version-latest", latest)
 
         # Determine if its a new version, and if so, output some more
         # information.
         current = Gem::Version.new(Vagrant::VERSION)
-        latest  = Gem::Version.new(data["version"])
+        latest  = Gem::Version.new(latest)
         if current >= latest
           @env.ui.success(" \n" + I18n.t(
             "vagrant.version_latest_installed"))