inspired by: https://github.com/middleman/middleman-blog/blob/master/lib/middleman-blog/extension.rb

lib/middleman-deploy/extension.rb

@@ -4,12 +4,15 @@ require "middleman-core"
 # Extension namespace
 module Middleman
   module Deploy
+    class Options < Struct.new(:host, :port, :user, :path); end
+
     class << self
 
-      # Called when user `activate`s your extension
-      def registered(app, options={})
-        # Setup extension-specific config
-        app.set :config_variable, false
+      def registered(app, options_hash={}, &block)
+        options = Options.new(options_hash)
+        yield options if block_given?
+
+        options.port ||= 22
 
         # Include class methods
         # app.extend ClassMethods
@@ -18,10 +21,21 @@ module Middleman
         # app.send :include, InstanceMethods
 
         app.after_configuration do
-          # Do something
+          if (!options.host || !options.user || !options.path)
+            raise <<EOF
 
-          # config_variable is now either the default or the user's
-          # setting from config.rb
+
+ERROR: middleman-deploy is not setup correctly. host, user, and path
+*must* be set in config.ru. For example:
+
+activate :deploy do |deploy|
+  deploy.user = "tvaughan"
+  deploy.host = "www.example.com"
+  deploy.path = "/srv/www/site"
+end
+
+EOF
+          end
         end
       end
       alias :included :registered