`config.ssh.forward_agent` option added [closes GH-105]

config/default.rb

@@ -11,6 +11,7 @@ Vagrant::Config.run do |config|
   config.ssh.max_tries = 10
   config.ssh.timeout = 30
   config.ssh.private_key_path = File.join(PROJECT_ROOT, 'keys', 'vagrant')
+  config.ssh.forward_agent = false
 
   config.vm.auto_port_range = (2200..2250)
   config.vm.box_ovf = "box.ovf"

lib/vagrant/config.rb

@@ -67,6 +67,7 @@ module Vagrant
       attr_accessor :max_tries
       attr_accessor :timeout
       attr_accessor :private_key_path
+      attr_accessor :forward_agent
 
       # The attribute(s) below do nothing. They are just kept here to
       # prevent syntax errors for backwards compat.

lib/vagrant/ssh.rb

@@ -31,12 +31,17 @@ module Vagrant
 
       check_key_permissions(options[:private_key_path])
 
+      # Command line options
+      command_options = ["-p #{options[:port]}", "-o UserKnownHostsFile=/dev/null",
+                         "-o StrictHostKeyChecking=no", "-i #{options[:private_key_path]}"]
+      command_options << "-o ForwardAgent=yes" if env.config.ssh.forward_agent
+
       # Some hackery going on here. On Mac OS X Leopard (10.5), exec fails
       # (GH-51). As a workaround, we fork and wait. On all other platforms,
       # we simply exec.
       pid = nil
       pid = fork if Util::Platform.leopard?
-      Kernel.exec "ssh -p #{options[:port]} -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -i #{options[:private_key_path]} #{options[:username]}@#{options[:host]}".strip if pid.nil?
+      Kernel.exec "ssh #{command_options.join(" ")} #{options[:username]}@#{options[:host]}".strip if pid.nil?
       Process.wait(pid) if pid
     end
 
@@ -46,6 +51,10 @@ module Vagrant
       # Check the key permissions to avoid SSH hangs
       check_key_permissions(env.config.ssh.private_key_path)
 
+      # Merge in any additional options
+      opts = opts.dup
+      opts[:forward_agent] = true if env.config.ssh.forward_agent
+
       Net::SSH.start(env.config.ssh.host,
                      env.config[:ssh][:username],
                      opts.merge( :port => port,

test/vagrant/ssh_test.rb

@@ -52,6 +52,17 @@ class SshTest < Test::Unit::TestCase
       @ssh.connect(args)
     end
 
+    should "add forward agent option if enabled" do
+      @env.config.ssh.forward_agent = true
+      ssh_exec_expect(@ssh.port,
+                      @env.config.ssh.private_key_path,
+                      @env.config.ssh.username,
+                      @env.config.ssh.host) do |args|
+        assert args =~ /-o ForwardAgent=yes/
+      end
+      @ssh.connect
+    end
+
     context "on leopard" do
       setup do
         Vagrant::Util::Platform.stubs(:leopard?).returns(true)
@@ -88,7 +99,7 @@ class SshTest < Test::Unit::TestCase
         assert arg =~ /-p #{port}/
         assert arg =~ /-i #{key_path}/
         assert arg =~ /#{uname}@#{host}/
-        # TODO options not tested for as they may be removed
+        yield arg if block_given?
         true
       end
     end
@@ -119,6 +130,16 @@ class SshTest < Test::Unit::TestCase
       @ssh.execute
     end
 
+    should "forward agent if configured" do
+      @env.config.ssh.forward_agent = true
+      Net::SSH.expects(:start).once.with() do |host, username, opts|
+        assert opts[:forward_agent]
+        true
+      end
+
+      @ssh.execute
+    end
+
     should "use custom host if set" do
       @env.config.ssh.host = "foo"
       Net::SSH.expects(:start).with(@env.config.ssh.host, @env.config.ssh.username, anything).once