@mcp-abap-adt/logger

Logger interface and implementations for MCP ABAP ADT packages.

Installation

npm install @mcp-abap-adt/logger

It needs @mcp-abap-adt/interfaces@^39.0.0, since 0.3.0. ILogger and LogLevel come from there, and nothing about them changed — the floor moved so that a consumer ends up with one copy of the contracts rather than two.

That is worth a check after installing:

npm ls @mcp-abap-adt/interfaces     # one version, deduped everywhere

Two copies compile and then misbehave: structurally identical interfaces from different files do not compare equal in TypeScript, so a value from one is rejected where the other is expected, with an error that reads as impossible.

For structured logging with Pino (optional):

npm install pino pino-pretty

PinoLogger works without them and falls back to DefaultLogger. It says so once on construction, outside production:

PinoLogger initialization error: Cannot find module 'pino'

That line is the fallback reporting itself, not a failure — logging continues. Set NODE_ENV=production to silence it, or install the two packages above. It appears once per logger, so a test run that builds one per file prints it per file.

Usage

DefaultLogger (Synchronous)

DefaultLogger provides synchronous logging with icons and level prefixes, ideal for tests and CLI tools:

import { defaultLogger, DefaultLogger, LogLevel } from '@mcp-abap-adt/logger';

// Use default logger singleton
defaultLogger.info('Hello, world!');
defaultLogger.debug('Debug message');
defaultLogger.error('Error message');
defaultLogger.warn('Warning message');

// Create custom logger instance with specific log level
const logger = new DefaultLogger(LogLevel.DEBUG);
logger.info('Test info');  // Output: [INFO] ℹ️ Test info
logger.debug('Test debug'); // Output: [DEBUG] 🐛 Test debug

PinoLogger (Asynchronous)

PinoLogger provides structured logging using Pino, ideal for server applications:

import { PinoLogger, LogLevel } from '@mcp-abap-adt/logger';

// Create Pino logger (falls back to DefaultLogger if pino is not installed)
const logger = new PinoLogger(LogLevel.DEBUG);
logger.info('Server started');  // Output: ℹ️ Server started (with pino-pretty formatting)
logger.debug('Debug info');
logger.error('Error occurred');
logger.warn('Warning message');

Note: PinoLogger uses async transport, so logs may appear after test completion in Jest. This is expected behavior for server use.

Log Levels

Log levels are defined in @mcp-abap-adt/interfaces and controlled by AUTH_LOG_LEVEL environment variable:

import { LogLevel } from '@mcp-abap-adt/interfaces';

// LogLevel enum values:
// LogLevel.ERROR = 0
// LogLevel.WARN = 1
// LogLevel.INFO = 2
// LogLevel.DEBUG = 3

Environment variable values:

• error - only errors
• warn - errors and warnings
• info - errors, warnings, and info (default)
• debug - all messages

export AUTH_LOG_LEVEL=debug

For backward compatibility, DEBUG_AUTH_LOG=true also sets level to debug.

Logger Interface

All logger implementations implement the ILogger interface from @mcp-abap-adt/interfaces:

import type { ILogger } from '@mcp-abap-adt/interfaces';

interface ILogger {
  info(message: string, meta?: any): void;
  debug(message: string, meta?: any): void;
  error(message: string, meta?: any): void;
  warn(message: string, meta?: any): void;
}

// Create custom logger
class MyCustomLogger implements ILogger {
  info(message: string, meta?: any): void {
    // Custom implementation
  }
  debug(message: string, meta?: any): void {
    // Custom implementation
  }
  error(message: string, meta?: any): void {
    // Custom implementation
  }
  warn(message: string, meta?: any): void {
    // Custom implementation
  }
}

Output Format

DefaultLogger output format:

• [INFO] ℹ️ message
• [DEBUG] 🐛 message
• [ERROR] 💥 message
• [WARN] ⚠️ message

PinoLogger output format (with pino-pretty):

• Structured JSON in production
• Pretty formatted with colors and icons in development (NODE_ENV !== 'production')

License

GNU Lesser General Public License v3.0 only (LGPL-3.0-only). Earlier published versions were MIT and stay MIT — a licence change is not retroactive.

Copyright © 2025–2026 Oleksii Kyslytsia

This library is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 3.

It is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

Both texts ship with the package and both are needed: LICENSE is the LGPL, COPYING is the GPL it is written on top of, since the LGPL is a set of additional permissions over the GPL and cannot be read alone.

What this means if you depend on this package. Linking it into your own program — importing it, as every consumer of an npm package does — does not put your program under the LGPL. What the licence asks is that changes to this library stay free, and that your users can replace it with their own build.