RefInCondition.py

"""
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
SPDX-License-Identifier: MIT-0
"""

from cfnlint.rules import CloudFormationLintRule, RuleMatch


class RefInCondition(CloudFormationLintRule):
    """Check if Ref value is a string"""

    id = "E1026"
    shortdesc = "Cannot reference resources in the Conditions block of the template"
    description = "Check that any Refs in the Conditions block uses no resources"
    source_url = "https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-conditions.html#w2ab2c21c28c21c45"
    tags = ["conditions", "functions", "ref"]

    def match(self, cfn):
        matches = []

        ref_objs = cfn.search_deep_keys("Ref")
        resource_names = cfn.get_resource_names()

        for ref_obj in ref_objs:
            if ref_obj[0] == "Conditions":
                value = ref_obj[-1]
                if isinstance(value, (str, int)):
                    if value in resource_names:
                        message = "Cannot reference resource {0} in the Conditions block of the template at {1}"
                        matches.append(
                            RuleMatch(
                                ref_obj[:-1],
                                message.format(value, "/".join(map(str, ref_obj[:-1]))),
                            )
                        )

        return matches