Add Ansible diff mode

Add the possibility to turn on Ansible diff mode by the new input parameter
diff_mode.

Signed-off-by: Ruediger Pluem <ruediger.pluem@vodafone.com>

Update lib/smart_proxy_ansible/runner/ansible_runner.rb

Co-authored-by: Adam Růžička <adamruzicka@users.noreply.github.com>

Author: rpluem-vf

lib/smart_proxy_ansible/runner/ansible_runner.rb

@@ -23,6 +23,7 @@ def initialize(input, suspended_action:, id: nil)
         @rex_command = action_input[:remote_execution_command]
         @check_mode = action_input[:check_mode]
         @job_check_mode = action_input[:job_check_mode]
+        @diff_mode = action_input[:diff_mode]
         @tags = action_input[:tags]
         @tags_flag = action_input[:tags_flag]
         @passphrase = action_input['secrets']['key_passphrase']
@@ -214,7 +215,7 @@ def start_ansible_runner
       end
 
       def cmdline
-        cmd_args = [tags_cmd, check_cmd].reject(&:empty?)
+        cmd_args = [tags_cmd, check_cmd, diff_cmd].reject(&:empty?)
         return nil unless cmd_args.any?
         cmd_args.join(' ')
       end
@@ -232,6 +233,10 @@ def check_cmd
         end
       end
 
+      def diff_cmd
+        diff_mode? ? '"--diff"' : ''
+      end
+
       def verbosity
         '-' + 'v' * @verbosity_level.to_i
       end
@@ -248,6 +253,10 @@ def job_check_mode?
         @job_check_mode == true
       end
 
+      def diff_mode?
+        @diff_mode == true
+      end
+
       def prepare_directory_structure
         inner = %w[inventory project env].map { |part| File.join(@root, part) }
         ([@root] + inner).each do |path|