verify arns differently than function names (#23966)

lib/ansible/modules/cloud/amazon/lambda_event.py

@@ -229,9 +229,12 @@ def validate_params(module, aws):
         module.fail_json(
             msg='Function name {0} is invalid. Names must contain only alphanumeric characters and hyphens.'.format(function_name)
         )
-    if len(function_name) > 64:
+    if len(function_name) > 64 and not function_name.startswith('arn:aws:lambda:'):
         module.fail_json(msg='Function name "{0}" exceeds 64 character limit'.format(function_name))
 
+    elif len(function_name) > 140 and function_name.startswith('arn:aws:lambda:'):
+        module.fail_json(msg='ARN "{0}" exceeds 140 character limit'.format(function_name))
+
     # check if 'function_name' needs to be expanded in full ARN format
     if not module.params['lambda_function_arn'].startswith('arn:aws:lambda:'):
         function_name = module.params['lambda_function_arn']