Value.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
from cfnlint.helpers import RESOURCE_SPECS


class Value(CloudFormationLintRule):
    """Check if Outputs have string values"""
    id = 'E6003'
    shortdesc = 'Outputs have values of strings'
    description = 'Making sure the outputs have strings as values'
    source_url = 'https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/outputs-section-structure.html'
    tags = ['outputs']

    def __init__(self):
        """Init """
        super(Value, self).__init__()
        self.resourcetypes = []

    def initialize(self, cfn):
        resourcespecs = RESOURCE_SPECS[cfn.regions[0]]
        self.resourcetypes = resourcespecs['ResourceTypes']

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

        template = cfn.template

        getatts = cfn.search_deep_keys('Fn::GetAtt')
        refs = cfn.search_deep_keys('Ref')
        # If using a getatt make sure the attribute of the resource
        # is not of Type List
        for getatt in getatts:
            if getatt[0] == 'Outputs':
                if getatt[2] == 'Value':
                    obj = getatt[-1]
                    if isinstance(obj, list):
                        objtype = template.get('Resources', {}).get(obj[0], {}).get('Type')
                        if objtype:
                            attribute = self.resourcetypes.get(
                                objtype, {}).get('Attributes', {}).get(obj[1], {}).get('Type')
                            if attribute == 'List':
                                if getatt[-4] != 'Fn::Join' and getatt[-3] != 1:
                                    message = 'Output {0} value {1} is of type list'
                                    matches.append(RuleMatch(
                                        getatt,
                                        message.format(getatt[1], '/'.join(obj))
                                    ))

        # If using a ref for an output make sure it isn't a
        # Parameter of Type List
        for ref in refs:
            if ref[0] == 'Outputs':
                if ref[2] == 'Value':
                    obj = ref[-1]
                    if isinstance(obj, six.string_types):
                        param = template.get('Parameters', {}).get(obj)
                        if param:
                            paramtype = param.get('Type')
                            if paramtype:
                                if paramtype.startswith('List<'):
                                    if ref[-4] != 'Fn::Join' and ref[-3] != 1:
                                        message = 'Output {0} value {1} is of type list'
                                        matches.append(RuleMatch(
                                            ref,
                                            message.format(ref[1], obj)
                                        ))

        return matches