@overture-stack/lyric/dist/src/config/logger.js

Data Submission system

import { createLogger, format, transports } from 'winston';
/**
 * Splits variadic logger arguments into a text message and an optional metadata object.
 * If the last argument is a plain object it is treated as structured metadata; all preceding
 * arguments are joined with ' - ' to form the message string.
 */
const splitArgs = (messages) => {
    const last = messages[messages.length - 1];
    const isMetaObject = last !== null && last !== undefined && typeof last === 'object' && !Array.isArray(last) && !(last instanceof Error);
    if (isMetaObject && messages.length > 1) {
        return {
            message: messages.slice(0, -1).join(' - '),
            meta: last,
        };
    }
    return { message: messages.join(' - ') };
};
/** Renders a metadata object as space-separated key=value pairs for human-readable output. */
const metaToString = (meta) => Object.entries(meta)
    .map(([k, v]) => `${k}=${typeof v === 'string' ? v : JSON.stringify(v)}`)
    .join(' ');
/**
 * Get a Logger instance for log messages.
 *
 * Supports two transports:
 * - Console: human-readable `timestamp [level]: message key=value ...` format, always active.
 * - JSON file (`logs/app.json`): full structured JSON for log aggregators; enabled via `config.json`.
 */
export const getLogger = (config) => {
    const transportList = [];
    const { combine, timestamp, colorize, printf, json, errors } = format;
    // Console transport: human-readable with metadata rendered as key=value pairs.
    transportList.push(new transports.Console({
        format: combine(timestamp(), colorize(), errors({ stack: true }), printf(({ timestamp, level, message, ...meta }) => {
            const metaKeys = Object.keys(meta).filter((k) => k !== 'stack');
            const metaStr = metaKeys.length ? ' ' + metaToString(meta) : '';
            return `${timestamp} [${level}]: ${message}${metaStr}`;
        })),
    }));
    // Plain-text file transport for pre-Kubernetes deployments that relied on file-based log shipping.
    if (config.file) {
        transportList.push(new transports.File({ filename: 'logs.log' }));
    }
    // JSON file transport for log aggregators (Kibana via Filebeat, etc.).
    if (config.json) {
        transportList.push(new transports.File({
            filename: 'logs/app.json',
            format: combine(timestamp(), errors({ stack: true }), json()),
        }));
    }
    const logger = createLogger({
        level: config.level || 'info',
        transports: transportList,
    });
    const emit = (fn) => (...messages) => {
        const { message, meta } = splitArgs(messages);
        fn(message, meta);
    };
    return {
        debug: emit(logger.debug.bind(logger)),
        warn: emit(logger.warn.bind(logger)),
        info: emit(logger.info.bind(logger)),
        error: emit(logger.error.bind(logger)),
    };
};