# ###################################
##       Rule Specification        ##
#####################################
# 
# Rule Identifier:
#   rds_instance_logging_enabled_check
# 
# Description:
#   This rules checks whether Amazon Relational Database Service (RDS) instances have all available log types configured for export to Amazon CloudWatch Logs.
# 
# Reports on:
#   AWS::RDS::DBInstance
# 
# Evaluates:
#   AWS CloudFormation, AWS CloudFormation hook
# 
# Rule Parameters:
#   None
# 
# Scenarios:
#   Scenario: 1
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document does not contain any RDS DB instance resources
#      Then: SKIP
#   Scenario: 2
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an RDS DB instance resource
#       And: 'Engine' is not one of 'mariadb', 'mysql',
#            'oracle-ee', 'oracle-se2', 'oracle-ee-cdb', 'oracle-se2-cdb',
#            'postgres', 'sqlserver-ee', 'sqlserver-se', 'sqlserver-ex', 'sqlserver-web'
#      Then: SKIP
#   Scenario: 3
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an RDS DB instance resource
#       And: 'Engine' is one of 'mariadb', 'mysql',
#            'oracle-ee', 'oracle-se2', 'oracle-ee-cdb', 'oracle-se2-cdb',
#            'postgres', 'sqlserver-ee', 'sqlserver-se', 'sqlserver-ex', 'sqlserver-web'
#       And: 'EnableCloudwatchLogsExports' has not been specified or has been specified
#             and is an empty list
#      Then: FAIL
#   Scenario: 4
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an RDS DB instance resource
#       And: 'Engine' is one of 'mariadb', 'mysql',
#            'oracle-ee', 'oracle-se2', 'oracle-ee-cdb', 'oracle-se2-cdb',
#            'postgres', 'sqlserver-ee', 'sqlserver-se', 'sqlserver-ex', 'sqlserver-web'
#       And: 'EnableCloudwatchLogsExports' has been specified and is a non-empty list
#       And: One or more log types in 'EnableCloudwatchLogsExports' are not supported by the specified 'Engine'
#      Then: FAIL
#   Scenario: 5
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an RDS DB instance resource
#       And: 'Engine' is one of 'mariadb', 'mysql',
#            'oracle-ee', 'oracle-se2', 'oracle-ee-cdb', 'oracle-se2-cdb',
#            'postgres', 'sqlserver-ee', 'sqlserver-se', 'sqlserver-ex', 'sqlserver-web'
#       And: 'EnableCloudwatchLogsExports' has been specified and is a non-empty list
#       And: 'EnableCloudwatchLogsExports' does not contain all log types supported by the specified 'Engine'
#      Then: FAIL
#   Scenario: 6
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an RDS DB instance resource
#       And: 'Engine'  is one of 'mariadb', 'mysql'
#       And: 'EnableCloudwatchLogsExports' has been specified
#       And: 'EnableCloudwatchLogsExports' value is a non-empty and all supported log types
#             are enabled - 'audit', 'error', 'general', 'slowquery'
#      Then: PASS
#   Scenario: 7
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an RDS DB instance resource
#       And: 'Engine' is 'postgres'
#       And: 'EnableCloudwatchLogsExports' has been specified
#       And: 'EnableCloudwatchLogsExports' value is a non-empty and all supported log types
#             are enabled - 'postgresql', 'upgrade'
#      Then: PASS
#   Scenario: 8
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an RDS DB instance resource
#       And: 'Engine' is one of 'sqlserver-ee', 'sqlserver-se', 'sqlserver-ex',
#            'sqlserver-web'
#       And: 'EnableCloudwatchLogsExports' has been specified
#       And: 'EnableCloudwatchLogsExports' value is a non-empty and all supported log types
#             are enabled - 'agent', 'error'
#      Then: PASS
#   Scenario: 9
#     Given: The input document is an AWS CloudFormation or CloudFormation hook document
#       And: The input document contains an RDS DB instance resource
#       And: 'Engine' is one of 'oracle-ee', 'oracle-se2', 'oracle-ee-cdb', 'oracle-se2-cdb',
#       And: 'EnableCloudwatchLogsExports' has been specified
#       And: 'EnableCloudwatchLogsExports' value is a non-empty and all supported log types
#             are enabled - 'alert', 'audit', 'listener', 'oemagent', 'trace'
#      Then: PASS

#
# Constants
#
let RDS_DB_INSTANCE_TYPE = "AWS::RDS::DBInstance"
let INPUT_DOCUMENT = this
let SUPPORTED_RDS_INSTANCE_ENGINES = [
    "mariadb", "mysql", "oracle-ee", "oracle-ee-cdb", "oracle-se2",
    "oracle-se2-cdb", "postgres", "sqlserver-ee", "sqlserver-se",
    "sqlserver-ex", "sqlserver-web"
]

let MYSQL_OR_MARIA_ENGINES_SUBTYPES = [ "mariadb", "mysql" ]
let POSTGRES_ENGINES_SUBTYPES = [ "postgres" ]
let SQLSERVER_ENGINES_SUBTYPES = [ "sqlserver-ee", "sqlserver-se", "sqlserver-ex", "sqlserver-web" ]
let ORACLE_ENGINES_SUBTYPES = [ "oracle-ee", "oracle-se2", "oracle-se1", "oracle-se" ]

let MYSQL_OR_MARIA_SUPPORTED_LOG_TYPES = [ "audit", "error", "general", "slowquery" ]
let POSTGRES_SUPPORTED_LOG_TYPES = [ "postgresql", "upgrade" ]
let SQLSERVER_SUPPORTED_LOG_TYPES = [ "agent", "error" ]
let ORACLE_SUPPORTED_LOG_TYPES = [ "alert", "audit", "listener", "oemagent", "trace" ]

#
# Assignments
#
let rds_db_instances = Resources.*[ Type == %RDS_DB_INSTANCE_TYPE ]

#
# Primary Rules
#
rule rds_instance_logging_enabled_check when is_cfn_template(%INPUT_DOCUMENT)
                                             %rds_db_instances not empty {
    check(%rds_db_instances.Properties)
        <<
        [CT.RDS.PR.14]: Require an Amazon RDS database instance to have logging configured
        [FIX]: Specify 'EnableCloudwatchLogsExports' with a list of all supported log types for the Amazon RDS database instance engine.
        >>
}

rule rds_instance_logging_enabled_check when is_cfn_hook(%INPUT_DOCUMENT, %RDS_DB_INSTANCE_TYPE) {
    check(%INPUT_DOCUMENT.%RDS_DB_INSTANCE_TYPE.resourceProperties)
        <<
        [CT.RDS.PR.14]: Require an Amazon RDS database instance to have logging configured
        [FIX]: Specify 'EnableCloudwatchLogsExports' with a list of all supported log types for the Amazon RDS database instance engine.
        >>
}

#
# Parameterized Rules
#
rule check(rds_db_instance) {
    %rds_db_instance [filter_engine(this)] {
        # Scenario: 3
        EnableCloudwatchLogsExports exists
        check_is_list_and_not_empty(EnableCloudwatchLogsExports)

        # Scenario: 4 and 5
        when Engine IN %MYSQL_OR_MARIA_ENGINES_SUBTYPES {
            %MYSQL_OR_MARIA_SUPPORTED_LOG_TYPES.* IN EnableCloudwatchLogsExports[*]
            EnableCloudwatchLogsExports.* IN %MYSQL_OR_MARIA_SUPPORTED_LOG_TYPES[*]
        }

        # Scenario: 4 and 6
        when Engine IN %POSTGRES_ENGINES_SUBTYPES {
            %POSTGRES_SUPPORTED_LOG_TYPES.* IN EnableCloudwatchLogsExports[*]
            EnableCloudwatchLogsExports.* IN %POSTGRES_SUPPORTED_LOG_TYPES[*]
        }

        # Scenario: 4 and 7
        when Engine IN %SQLSERVER_ENGINES_SUBTYPES {
            %SQLSERVER_SUPPORTED_LOG_TYPES.* in EnableCloudwatchLogsExports[*]
            EnableCloudwatchLogsExports.* IN %SQLSERVER_SUPPORTED_LOG_TYPES[*]
        }

        # Scenario: 4 and 8
        when Engine IN %ORACLE_ENGINES_SUBTYPES {
            %ORACLE_SUPPORTED_LOG_TYPES.* in EnableCloudwatchLogsExports[*]
            EnableCloudwatchLogsExports.* IN %ORACLE_SUPPORTED_LOG_TYPES[*]
        }
    }
}

rule filter_engine(db_properties) {
    %db_properties {
        # Scenario: 2
        Engine exists
        Engine in %SUPPORTED_RDS_INSTANCE_ENGINES
    }
}

#
# Utility Rules
#
rule check_is_list_and_not_empty(value) {
    %value {
        this is_list
        this not empty
    }
}

rule is_cfn_template(doc) {
    %doc {
        AWSTemplateFormatVersion exists  or
        Resources exists
    }
}

rule is_cfn_hook(doc, RESOURCE_TYPE) {
    %doc.%RESOURCE_TYPE.resourceProperties exists
}