| """ |
| Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. |
| SPDX-License-Identifier: MIT-0 |
| """ |
|
|
| from collections import deque |
| from typing import Any |
|
|
| from cfnlint.jsonschema import ValidationError, ValidationResult |
| from cfnlint.jsonschema.protocols import Validator |
| from cfnlint.rules import CloudFormationLintRule |
|
|
|
|
| class SubNotJoin(CloudFormationLintRule): |
| """Check if Join is being used with no join characters""" |
|
|
| id = "I1022" |
| shortdesc = "Use Sub instead of Join" |
| description = ( |
| "Prefer a sub instead of Join when using a join delimiter that is empty" |
| ) |
| source_url = "https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-sub.html" |
| tags = ["functions", "sub", "join"] |
|
|
| def _check_element(self, element): |
| if isinstance(element, dict): |
| if len(element) == 1: |
| for key, value in element.items(): |
| if key in ["Fn::Sub"]: |
| if not isinstance(value, str): |
| return False |
| elif key not in ["Ref", "Fn::GetAtt"]: |
| return False |
|
|
| return True |
|
|
| def _check_elements(self, elements): |
| for element in elements: |
| if not self._check_element(element): |
| return False |
|
|
| return True |
|
|
| def validate( |
| self, validator: Validator, s: Any, instance: Any, schema: Any |
| ) -> ValidationResult: |
| if validator.cfn.is_cdk_template(): |
| return |
|
|
| key = list(instance.keys())[0] |
| value = instance.get(key) |
|
|
| if value[0] != "": |
| return |
|
|
| if self._check_elements(value[1]): |
| yield ValidationError( |
| ("Prefer using Fn::Sub over Fn::Join with an" " empty delimiter"), |
| path=deque([key, 0]), |
| rule=self, |
| ) |
|
|
