@aws-lambda-powertools/logger/lib/esm/formatter/PowertoolsLogFormatter.js

The logging package for the Powertools for AWS Lambda (TypeScript) library

import { LogFormatter } from './LogFormatter.js';
import { LogItem } from './LogItem.js';
/**
 * This class is used to transform a set of log key-value pairs
 * in the Powertools for AWS Lambda default structure log format.
 *
 * @class
 * @extends {LogFormatter}
 */
class PowertoolsLogFormatter extends LogFormatter {
    /**
     * List of keys to order log attributes by.
     *
     * This can be a set of keys or an array of keys.
     */
    #logRecordOrder;
    constructor(options) {
        super(options);
        this.#logRecordOrder = options?.logRecordOrder;
    }
    /**
     * It formats key-value pairs of log attributes.
     *
     * @param {UnformattedAttributes} attributes - unformatted attributes
     * @param {LogAttributes} additionalLogAttributes - additional log attributes
     */
    formatAttributes(attributes, additionalLogAttributes) {
        const baseAttributes = {
            level: attributes.logLevel,
            message: attributes.message,
            timestamp: this.formatTimestamp(attributes.timestamp),
            service: attributes.serviceName,
            cold_start: attributes.lambdaContext?.coldStart,
            function_arn: attributes.lambdaContext?.invokedFunctionArn,
            function_memory_size: attributes.lambdaContext?.memoryLimitInMB,
            function_name: attributes.lambdaContext?.functionName,
            function_request_id: attributes.lambdaContext?.awsRequestId,
            sampling_rate: attributes.sampleRateValue,
            xray_trace_id: attributes.xRayTraceId,
        };
        // If logRecordOrder is not set, return the log item with the attributes in the order they were added
        if (this.#logRecordOrder === undefined) {
            return new LogItem({ attributes: baseAttributes }).addAttributes(additionalLogAttributes);
        }
        const orderedAttributes = {};
        // If logRecordOrder is set, order the attributes in the log item
        for (const key of this.#logRecordOrder) {
            if (key in baseAttributes && !(key in orderedAttributes)) {
                orderedAttributes[key] = baseAttributes[key];
            }
            else if (key in additionalLogAttributes &&
                !(key in orderedAttributes)) {
                orderedAttributes[key] = additionalLogAttributes[key];
            }
        }
        // Add remaining attributes from baseAttributes
        for (const key in baseAttributes) {
            if (!(key in orderedAttributes)) {
                orderedAttributes[key] = baseAttributes[key];
            }
        }
        // Add remaining attributes from additionalLogAttributes
        for (const key in additionalLogAttributes) {
            if (!(key in orderedAttributes)) {
                orderedAttributes[key] = additionalLogAttributes[key];
            }
        }
        const powertoolsLogItem = new LogItem({
            attributes: orderedAttributes,
        });
        return powertoolsLogItem;
    }
}
export { PowertoolsLogFormatter };