Works with public keys now, for passwordless operation

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2000 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

7 files changed, 181 insertions, 31 deletions

diff --git a/switchtower/CHANGELOG b/switchtower/CHANGELOG
index c645bff275..f40d897780 100644
--- a/switchtower/CHANGELOG
+++ b/switchtower/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Works with public keys now, for passwordless deployment
+
 * Subversion module recognizes the password prompt for HTTP authentication
 
 * Preserve +x on scripts when using darcs #1929 [Scott Barron]
diff --git a/switchtower/lib/switchtower/actor.rb b/switchtower/lib/switchtower/actor.rb
index db25ca99c2..012f4a1f55 100644
--- a/switchtower/lib/switchtower/actor.rb
+++ b/switchtower/lib/switchtower/actor.rb
@@ -1,7 +1,7 @@
 require 'erb'
-require 'net/ssh'
 require 'switchtower/command'
 require 'switchtower/gateway'
+require 'switchtower/ssh'
 
 module SwitchTower
 
@@ -12,7 +12,7 @@ module SwitchTower
   # new actor via Configuration#actor.
   class Actor
 
-    # An adaptor for making the Net::SSH interface look and act like that of the
+    # An adaptor for making the SSH interface look and act like that of the
     # Gateway class.
     class DefaultConnectionFactory #:nodoc:
       def initialize(config)
@@ -20,8 +20,7 @@ module SwitchTower
       end
 
       def connect_to(server)
-        Net::SSH.start(server, :username => @config.user,
-          :password => @config.password)
+        SSH.connect(server, @config)
       end
     end
 
@@ -40,7 +39,7 @@ module SwitchTower
     # instances of Actor::Task.
     attr_reader :tasks
 
-    # A hash of the Net::SSH sessions that are currently open and available.
+    # A hash of the SSH sessions that are currently open and available.
     # Because sessions are constructed lazily, this will only contain
     # connections to those servers that have been the targets of one or more
     # executed tasks.
diff --git a/switchtower/lib/switchtower/gateway.rb b/switchtower/lib/switchtower/gateway.rb
index 531c34ba5f..46f8361e9a 100644
--- a/switchtower/lib/switchtower/gateway.rb
+++ b/switchtower/lib/switchtower/gateway.rb
@@ -1,5 +1,5 @@
 require 'thread'
-require 'net/ssh'
+require 'switchtower/ssh'
 
 Thread.abort_on_exception = true
 
@@ -36,9 +36,7 @@ module SwitchTower
 
       @thread = Thread.new do
         @config.logger.trace "starting connection to gateway #{server}"
-        Net::SSH.start(server, :username => @config.user,
-          :password => @config.password
-        ) do |@session|
+        SSH.connect(server, @config) do |@session|
           @config.logger.trace "gateway connection established"
           @mutex.synchronize { waiter.signal }
           connection = @session.registry[:connection][:driver]
@@ -93,9 +91,8 @@ module SwitchTower
 
           begin
             @session.forward.local(port, key, 22)
-            @pending_forward_requests[key] =
-              Net::SSH.start('127.0.0.1', :username => @config.user,
-                :password => @config.password, :port => port)
+            @pending_forward_requests[key] = SSH.connect('127.0.0.1', @config,
+              port)
             @config.logger.trace "connection to #{key} via gateway established"
           rescue Object
             @pending_forward_requests[key] = nil
diff --git a/switchtower/lib/switchtower/ssh.rb b/switchtower/lib/switchtower/ssh.rb
new file mode 100644
index 0000000000..b810f20573
--- /dev/null
+++ b/switchtower/lib/switchtower/ssh.rb
@@ -0,0 +1,30 @@
+require 'net/ssh'
+
+module SwitchTower
+  # A helper class for dealing with SSH connections.
+  class SSH
+    # An abstraction to make it possible to connect to the server via public key
+    # without prompting for the password. If the public key authentication fails
+    # this will fall back to password authentication.
+    #
+    # If a block is given, the new session is yielded to it, otherwise the new
+    # session is returned.
+    def self.connect(server, config, port=22, &block)
+      methods = [ %w(publickey hostbased), %w(password keyboard-interactive) ]
+      password_value = nil
+
+      begin
+        Net::SSH.start(server,
+          :username => config.user,
+          :password => password_value,
+          :port => port,
+          :auth_methods => methods.shift,
+          &block)
+      rescue Net::SSH::AuthenticationFailed
+        raise if methods.empty?
+        password_value = config.password
+        retry
+      end
+    end
+  end
+end
diff --git a/switchtower/test/scm/subversion_test.rb b/switchtower/test/scm/subversion_test.rb
index 47942d9b9c..fa65714b6b 100644
--- a/switchtower/test/scm/subversion_test.rb
+++ b/switchtower/test/scm/subversion_test.rb
@@ -1,28 +1,10 @@
 $:.unshift File.dirname(__FILE__) + "/../../lib"
 
+require File.dirname(__FILE__) + "/../utils"
 require 'test/unit'
 require 'switchtower/scm/subversion'
 
 class ScmSubversionTest < Test::Unit::TestCase
-  class MockLogger
-    def info(msg,pfx=nil) end
-    def debug(msg,pfx=nil) end
-  end
-
-  class MockConfiguration < Hash
-    def logger
-      @logger ||= MockLogger.new
-    end
-
-    def method_missing(sym, *args)
-      if args.length == 0
-        self[sym]
-      else
-        super
-      end
-    end
-  end
-
   class SubversionTest < SwitchTower::SCM::Subversion
     attr_accessor :story
     attr_reader   :last_path
diff --git a/switchtower/test/ssh_test.rb b/switchtower/test/ssh_test.rb
new file mode 100644
index 0000000000..60e791beb3
--- /dev/null
+++ b/switchtower/test/ssh_test.rb
@@ -0,0 +1,104 @@
+$:.unshift File.dirname(__FILE__) + "/../lib"
+
+require File.dirname(__FILE__) + "/utils"
+require 'test/unit'
+require 'switchtower/ssh'
+
+class SSHTest < Test::Unit::TestCase
+  class MockSSH
+    AuthenticationFailed = Net::SSH::AuthenticationFailed
+
+    class <<self
+      attr_accessor :story
+      attr_accessor :invocations
+    end
+
+    def self.start(server, opts, &block)
+      @invocations << [server, opts, block]
+      err = story.shift
+      raise err if err
+    end
+  end
+
+  def setup
+    @config = MockConfiguration.new
+    @config[:user] = 'demo'
+    @config[:password] = 'c0c0nutfr0st1ng'
+    MockSSH.story = []
+    MockSSH.invocations = []
+  end
+
+  def test_publickey_auth_succeeds_default_port_no_block
+    Net.const_during(:SSH, MockSSH) do
+      SwitchTower::SSH.connect('demo.server.i', @config)
+    end
+
+    assert_equal 1, MockSSH.invocations.length
+    assert_equal 'demo.server.i', MockSSH.invocations.first[0]
+    assert_equal 22, MockSSH.invocations.first[1][:port]
+    assert_equal 'demo', MockSSH.invocations.first[1][:username]
+    assert_nil MockSSH.invocations.first[1][:password]
+    assert_equal %w(publickey hostbased),
+      MockSSH.invocations.first[1][:auth_methods]
+    assert_nil MockSSH.invocations.first[2]
+  end
+
+  def test_publickey_auth_succeeds_explicit_port_no_block
+    Net.const_during(:SSH, MockSSH) do
+      SwitchTower::SSH.connect('demo.server.i', @config, 23)
+    end
+
+    assert_equal 1, MockSSH.invocations.length
+    assert_equal 23, MockSSH.invocations.first[1][:port]
+    assert_nil MockSSH.invocations.first[2]
+  end
+
+  def test_publickey_auth_succeeds_with_block
+    Net.const_during(:SSH, MockSSH) do
+      SwitchTower::SSH.connect('demo.server.i', @config) do |session|
+      end
+    end
+
+    assert_equal 1, MockSSH.invocations.length
+    assert_instance_of Proc, MockSSH.invocations.first[2]
+  end
+
+  def test_publickey_auth_fails
+    MockSSH.story << Net::SSH::AuthenticationFailed
+
+    Net.const_during(:SSH, MockSSH) do
+      SwitchTower::SSH.connect('demo.server.i', @config)
+    end
+
+    assert_equal 2, MockSSH.invocations.length
+
+    assert_nil MockSSH.invocations.first[1][:password]
+    assert_equal %w(publickey hostbased),
+      MockSSH.invocations.first[1][:auth_methods]
+
+    assert_equal 'c0c0nutfr0st1ng', MockSSH.invocations.last[1][:password]
+    assert_equal %w(password keyboard-interactive),
+      MockSSH.invocations.last[1][:auth_methods]
+  end
+
+  def test_password_auth_fails
+    MockSSH.story << Net::SSH::AuthenticationFailed
+    MockSSH.story << Net::SSH::AuthenticationFailed
+
+    Net.const_during(:SSH, MockSSH) do
+      assert_raises(Net::SSH::AuthenticationFailed) do
+        SwitchTower::SSH.connect('demo.server.i', @config)
+      end
+    end
+
+    assert_equal 2, MockSSH.invocations.length
+
+    assert_nil MockSSH.invocations.first[1][:password]
+    assert_equal %w(publickey hostbased),
+      MockSSH.invocations.first[1][:auth_methods]
+
+    assert_equal 'c0c0nutfr0st1ng', MockSSH.invocations.last[1][:password]
+    assert_equal %w(password keyboard-interactive),
+      MockSSH.invocations.last[1][:auth_methods]
+  end
+end
diff --git a/switchtower/test/utils.rb b/switchtower/test/utils.rb
new file mode 100644
index 0000000000..b483f0c005
--- /dev/null
+++ b/switchtower/test/utils.rb
@@ -0,0 +1,36 @@
+class Module
+  def const_during(constant, value)
+    if const_defined?(constant)
+      overridden = true
+      saved = const_get(constant)
+      remove_const(constant)
+    end
+
+    const_set(constant, value)
+    yield
+  ensure
+    if overridden
+      remove_const(constant)
+      const_set(constant, saved)
+    end
+  end
+end
+
+class MockLogger
+  def info(msg,pfx=nil) end
+  def debug(msg,pfx=nil) end
+end
+
+class MockConfiguration < Hash
+  def logger
+    @logger ||= MockLogger.new
+  end
+
+  def method_missing(sym, *args)
+    if args.length == 0
+      self[sym]
+    else
+      super
+    end
+  end
+end