Implemented file content diff for replace module (#4479)

lib/ansible/modules/files/replace.py

@@ -141,15 +141,25 @@ def main():
         contents = f.read()
         f.close()
 
+    if module._diff:
+        diff = {
+            'before_header': dest,
+            'before': contents,
+        }
+
     mre = re.compile(params['regexp'], re.MULTILINE)
     result = re.subn(mre, params['replace'], contents, 0)
 
     if result[1] > 0 and contents != result[0]:
         msg = '%s replacements made' % result[1]
         changed = True
+        if module._diff:
+            diff['after_header'] = dest
+            diff['after'] = result[0]
     else:
         msg = ''
         changed = False
+        diff = dict()
 
     if changed and not module.check_mode:
         if params['backup'] and os.path.exists(dest):
@@ -159,7 +169,7 @@ def main():
         write_changes(module, result[0], dest)
 
     msg, changed = check_file_attrs(module, changed, msg)
-    module.exit_json(changed=changed, msg=msg)
+    module.exit_json(changed=changed, msg=msg, diff=diff)
 
 # this is magic, see lib/ansible/module_common.py
 from ansible.module_utils.basic import *