@chainlink/mcp-server/dist/utils/logger.js

Prototype MCP Server for CLL

"use strict";
/**
 * @fileoverview Simple logging utility for MCP server applications
 *
 * Provides structured logging with different severity levels while respecting
 * MCP protocol requirements. All output goes to stderr since stdout is reserved
 * for JSON-RPC message communication in MCP servers.
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.Logger = void 0;
const config_1 = require("../config");
/**
 * Static logger class for structured application logging
 *
 * Provides timestamped logging with multiple severity levels. Designed specifically
 * for MCP (Model Context Protocol) servers where stdout must remain clear for
 * JSON-RPC communication, so all log output is directed to stderr.
 *
 * Features:
 * - Timestamped log entries with ISO format
 * - Multiple severity levels (debug, info, warn, error)
 * - Debug logging controlled by DEBUG environment variable
 * - MCP-compliant output routing (stderr only)
 *
 * @class Logger
 */
class Logger {
    /**
     * Core logging method that formats and outputs log messages
     *
     * All messages are timestamped and formatted consistently. Debug messages
     * are only output when the DEBUG environment variable is set.
     *
     * @param level - Severity level of the log message
     * @param message - Text content to log
     * @static
     */
    static log(level, message) {
        const timestamp = new Date().toISOString();
        const formattedMessage = `[${timestamp}] ${level.toUpperCase()}: ${message}`;
        // In MCP servers, all output must go to stderr since stdout is reserved for JSON-RPC messages
        switch (level) {
            case "debug":
                if (config_1.config.env.debug) {
                    console.error(formattedMessage);
                }
                break;
            default:
                console.error(formattedMessage);
        }
    }
    /**
     * Log a debug message (only shown when DEBUG env var is set)
     *
     * @param message - Debug message to log
     * @static
     */
    static debug(message) {
        this.log("debug", message);
    }
    /**
     * Log an informational message
     *
     * @param message - Information message to log
     * @static
     */
    static info(message) {
        this.log("info", message);
    }
    /**
     * Log a warning message
     *
     * @param message - Warning message to log
     * @static
     */
    static warn(message) {
        this.log("warn", message);
    }
    /**
     * Log an error message
     *
     * @param message - Error message to log
     * @static
     */
    static error(message) {
        this.log("error", message);
    }
}
exports.Logger = Logger;
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