#
#####################################
##           Gherkin               ##
#####################################
# Rule Identifier:
#   OPENSEARCH_DATA_NODE_FAULT_TOLERANCE
#
# Description:
#   OpenSearchService domains are configured with at least three data nodes and zone awareness enabled.
#
# Reports on:
#   AWS::OpenSearchService::Domain
#
# Evaluates:
#   AWS CloudFormation
#
# Rule Parameters:
#   NA
#
# Scenarios:
# a) SKIP: when there are no OpenSearchService Domain Resources 
# b) SKIP: when metadata has rule suppression for OPENSEARCH_DATA_NODE_FAULT_TOLERANCE
# c) FAIL: when OpenSearchService Domain Resources are missing ClusterConfig.ZoneAwarenessEnabled or ClusterConfig.InstanceCount
# d) FAIL: when OpenSearchService Domain Resources have ClusterConfig.ZoneAwarenessEnabled set to a value other than true 
# e) FAIL: when OpenSearchService Domain Resources have ClusterConfig.InstanceCount set to an integer value less than three (<3) 
# f) PASS: when OpenSearchService Domain Resources have ClusterConfig.ZoneAwarenessEnabled set to true and 
#          ClusterConfig.InstanceCount set to an integer value greater than or equal to three (>= 3) 

#
# Select all OpenSearchService domains from incoming template
#
let opensearch_data_node_fault_tolerance = Resources.*[ Type == "AWS::OpenSearchService::Domain"
  Metadata.guard.SuppressedRules not exists or
  Metadata.guard.SuppressedRules.* != "OPENSEARCH_DATA_NODE_FAULT_TOLERANCE"
]

rule OPENSEARCH_DATA_NODE_FAULT_TOLERANCE when %opensearch_data_node_fault_tolerance !empty {
    %opensearch_data_node_fault_tolerance.Properties { 
        ClusterConfig exists
        ClusterConfig is_struct

        ClusterConfig {
            ZoneAwarenessEnabled exists
            ZoneAwarenessEnabled == true
                <<
                    Violation: OpenSearchService domains are configured with at least three data nodes and zone awareness enabled
                    Fix: In ClusterConfig, set ZoneAwarenessEnabled to true and InstanceCount to an integer value greater than 3.
                >>
            InstanceCount exists
            InstanceCount >= 3
                <<
                    Violation: OpenSearchService domains are configured with at least three data nodes and zone awareness enabled
                    Fix: In ClusterConfig, set ZoneAwarenessEnabled to true and InstanceCount to an integer value greater than 3.
                >>
        }
    }
}