AWS Config Custom Rule - AWS Lambda (utiity)

utility.js

const aws = require('aws-sdk');
const config = new aws.ConfigService();

/**
 * Get the configurationItem for the resource using the getResourceConfigHistory API.
 */ 
async function getConfigurationFromHistory(configurationHistory, callback) {
    const params = { 
        resourceType: configurationHistory.resourceType,
        resourceId: configurationHistory.resourceId,
        laterTime: new Date(configurationHistory.configurationItemCaptureTime),
        limit: 1,
    };
    const data = await config.getResourceConfigHistory(params).promise();
    return data.configurationItems[0];
}

/**
 * Convert the oversized configuration item from the API model to the original invocation model.
 */ 
function convertApiConfiguration(apiConfiguration) {
    apiConfiguration.awsAccountId = apiConfiguration.accountId;
    apiConfiguration.ARN = apiConfiguration.arn;
    apiConfiguration.configurationStateMd5Hash = apiConfiguration.configurationItemMD5Hash;
    apiConfiguration.configurationItemVersion = apiConfiguration.version;
    apiConfiguration.configuration = JSON.parse(apiConfiguration.configuration);
    if ({}.hasOwnProperty.call(apiConfiguration, 'relationships')) {
        for (let i = 0; i < apiConfiguration.relationships.length; i++) {
            apiConfiguration.relationships[i].name = apiConfiguration.relationships[i].relationshipName;
        }
    }
    return apiConfiguration;
}

/**
 * Based on the message type, get the configuration item either from the configurationItem object in the invoking event
 * or with the getResourceConfigHistory API in the getConfiguration function.
 */ 
async function getConfigurationItem(invokingEvent, callback) {
    if (invokingEvent.messageType === 'OversizedConfigurationItemChangeNotification') {
        const apiConfigurationItem = await getConfigurationFromHistory(invokingEvent.configurationItemSummary);
        return convertApiConfiguration(apiConfigurationItem);
    } else {
        return invokingEvent.configurationItem;
    }
}

/**
 * Check whether the resource has been deleted. If the resource was deleted, then the evaluation returns not applicable.
 */ 
function isApplicable(configurationItem, event) {
    const status = configurationItem.configurationItemStatus;
    const eventLeftScope = event.eventLeftScope;
    return (status === 'OK' || status === 'ResourceDiscovered') && eventLeftScope === false;
}