Split.py

"""
Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
SPDX-License-Identifier: MIT-0
"""
import six
from cfnlint.rules import CloudFormationLintRule
from cfnlint.rules import RuleMatch


class Split(CloudFormationLintRule):
    """Check if Split values are correct"""
    id = 'E1018'
    shortdesc = 'Split validation of parameters'
    description = 'Making sure the split function is properly configured'
    source_url = 'https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-split.html'
    tags = ['functions', 'split']

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

        split_objs = cfn.search_deep_keys('Fn::Split')

        supported_functions = [
            'Fn::Base64',
            'Fn::FindInMap',
            'Fn::GetAZs',
            'Fn::GetAtt',
            'Fn::If',
            'Fn::ImportValue',
            'Fn::Join',
            'Fn::Select',
            'Fn::Sub',
            'Ref',
        ]

        for split_obj in split_objs:
            split_value_obj = split_obj[-1]
            tree = split_obj[:-1]
            if isinstance(split_value_obj, list):
                if len(split_value_obj) == 2:
                    split_delimiter = split_value_obj[0]
                    split_string = split_value_obj[1]
                    if not isinstance(split_delimiter, six.string_types):
                        message = 'Split delimiter has to be of type string for {0}'
                        matches.append(RuleMatch(
                            tree + [0], message.format('/'.join(map(str, tree)))))
                    if isinstance(split_string, dict):
                        if len(split_string) == 1:
                            for key, _ in split_string.items():
                                if key not in supported_functions:
                                    message = 'Fn::Split doesn\'t support the function {0} at {1}'
                                    matches.append(RuleMatch(
                                        tree + [key], message.format(key, '/'.join(map(str, tree)))))
                        else:
                            message = 'Split list of singular function or string for {0}'
                            matches.append(RuleMatch(
                                tree, message.format('/'.join(map(str, tree)))))
                    elif not isinstance(split_string, six.string_types):
                        message = 'Split has to be of type string or valid function for {0}'
                        matches.append(RuleMatch(
                            tree, message.format('/'.join(map(str, tree)))))
                else:
                    message = 'Split should be an array of 2 for {0}'
                    matches.append(RuleMatch(
                        tree, message.format('/'.join(map(str, tree)))))
            else:
                message = 'Split should be an array of 2 for {0}'
                matches.append(RuleMatch(
                    tree, message.format('/'.join(map(str, tree)))))
        return matches