switchtower: add diff_from_last_deploy task (currently only works wit…

…h subversion)

git-svn-id: http://svn.rubyonrails.org/rails/tools/switchtower@2452 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Add diff_from_last_deploy task (currently only works with subversion)
+
 * Add deploy_with_migrations task.
 
 * Make the migrate task more customizable.

lib/switchtower/recipes/standard.rb

@@ -162,3 +162,14 @@
   rollback_code
   restart
 end
+
+desc <<DESC
+Displays the diff between HEAD and what was last deployed. (Not available
+with all SCM's.)
+DESC
+task :diff_from_last_deploy do
+  diff = source.diff(self)
+  puts
+  puts diff
+  puts
+end

lib/switchtower/scm/base.rb

@@ -13,6 +13,14 @@ def latest_revision
         nil
       end
 
+      def current_revision(actor)
+        raise "#{self.class} doesn't support querying the deployed revision"
+      end
+
+      def diff(actor, from=nil, to=nil)
+        raise "#{self.class} doesn't support diff(from, to)"
+      end
+
       private
 
         def run_checkout(actor, guts, &block)

lib/switchtower/scm/subversion.rb

@@ -34,6 +34,33 @@ def latest_revision
         @latest_revision
       end
 
+      # Return the number of the revision currently deployed.
+      def current_revision(actor)
+        latest = actor.releases.last
+        grep = %(grep " #{latest}$" #{configuration.deploy_to}/revisions.log)
+        result = ""
+        actor.run(grep, :once => true) do |ch, str, out|
+          result << out if str == :out
+          raise "could not determine current revision" if str == :err
+        end
+
+        date, time, user, rev, dir = result.split
+        raise "current revision not found in revisions.log" unless dir == latest
+
+        rev.to_i
+      end
+
+      # Return a string containing the diff between the two revisions. +from+
+      # and +to+ may be in any format that svn recognizes as a valid revision
+      # identifier. If +from+ is +nil+, it defaults to the last deployed
+      # revision. If +to+ is +nil+, it defaults to HEAD.
+      def diff(actor, from=nil, to=nil)
+        from ||= current_revision(actor)
+        to ||= "HEAD"
+
+        `svn diff #{configuration.repository}@#{from} #{configuration.repository}@#{to}`
+      end
+
       # Check out (on all servers associated with the current task) the latest
       # revision. Uses the given actor instance to execute the command. If
       # svn asks for a password this will automatically provide it (assuming