Ebs.py

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


class Ebs(CloudFormationLintRule):
    """Check Ec2 Ebs Resource Properties"""
    id = 'E2504'
    shortdesc = 'Check Ec2 Ebs Properties'
    description = 'See if Ec2 Ebs Properties are valid'
    source_url = 'https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-ec2-blockdev-template.html'
    tags = ['properties', 'ec2', 'ebs']

    def _checkEbs(self, cfn, ebs, path):
        matches = []

        if isinstance(ebs, dict):
            volume_types_obj = cfn.get_values(ebs, 'VolumeType')
            iops_obj = cfn.get_values(ebs, 'Iops')
            if volume_types_obj is not None:
                for volume_type_obj in volume_types_obj:
                    volume_type = volume_type_obj.get('Value')
                    if isinstance(volume_type, six.string_types):
                        if volume_type in ('io1', 'io2'):
                            if iops_obj is None:
                                pathmessage = path[:] + ['VolumeType']
                                message = 'VolumeType {0} requires Iops to be specified for {1}'
                                matches.append(
                                    RuleMatch(
                                        pathmessage,
                                        message.format(volume_type, '/'.join(map(str, pathmessage)))))
                        elif volume_type in ('gp2', 'st1', 'sc1', 'standard'):
                            if iops_obj is not None:
                                pathmessage = path[:] + ['Iops']
                                message = 'Iops shouldn\'t be defined for type {0} for {1}'
                                matches.append(
                                    RuleMatch(
                                        pathmessage,
                                        message.format(volume_type, '/'.join(map(str, pathmessage)))))

        return matches

    def match(self, cfn):
        """Check Ec2 Ebs Resource Parameters"""

        matches = []

        results = cfn.get_resource_properties(['AWS::EC2::Instance', 'BlockDeviceMappings'])
        results.extend(cfn.get_resource_properties(
            ['AWS::AutoScaling::LaunchConfiguration', 'BlockDeviceMappings']))
        for result in results:
            path = result['Path']
            if isinstance(result['Value'], list):
                for index, properties in enumerate(result['Value']):
                    virtual_name = properties.get('VirtualName')
                    ebs = properties.get('Ebs')
                    if virtual_name:
                        # switch to regex
                        if not re.match(r'^ephemeral([0-9]|[1][0-9]|[2][0-3])$', virtual_name):
                            pathmessage = path[:] + [index, 'VirtualName']
                            message = 'Property VirtualName should be of type ephemeral(n) for {0}'
                            matches.append(
                                RuleMatch(pathmessage, message.format('/'.join(map(str, pathmessage)))))
                    elif ebs:
                        matches.extend(self._checkEbs(cfn, ebs, path[:] + [index, 'Ebs']))
        return matches