npm install pino pino-pretty

const pino = require('pino');

const logger = pino({
  level: process.env.LOG_LEVEL || 'info',
});

// 日志级别（从低到高）
logger.trace('详细跟踪信息');   // 10
logger.debug('调试信息');       // 20
logger.info('普通信息');        // 30
logger.warn('警告信息');        // 40
logger.error('错误信息');       // 50
logger.fatal('致命错误');       // 60

// 带上下文的日志
logger.info({ userId: 123, action: 'login' }, '用户登录成功');
logger.error({ err: new Error('数据库连接失败'), db: 'primary' }, '连接错误');

// 输出（JSON 格式）：
// {"level":30,"time":1715337600000,"msg":"用户登录成功","userId":123,"action":"login"}
// {"level":50,"time":1715337600001,"msg":"连接错误","err":{"type":"Error","message":"..."},"db":"primary"}

const baseLogger = pino({ level: 'info' });

// 为不同模块创建子 Logger
const dbLogger = baseLogger.child({ module: 'database' });
const apiLogger = baseLogger.child({ module: 'api' });
const authLogger = baseLogger.child({ module: 'auth', component: 'jwt' });

dbLogger.info({ query: 'SELECT * FROM users' }, '查询执行');
apiLogger.info({ method: 'GET', path: '/api/users' }, '请求处理');
authLogger.warn({ userId: 123 }, '令牌即将过期');

const express = require('express');
const pino = require('pino');
const pinoHttp = require('pino-http');

const app = express();
const logger = pino({ level: 'info' });

// 请求日志中间件
app.use(pinoHttp({
  logger,
  // 自定义请求属性
  customLogLevel: (req, res, err) => {
    if (res.statusCode >= 500) return 'error';
    if (res.statusCode >= 400) return 'warn';
    return 'info';
  },
  customSuccessMessage: (req, res) => {
    return `${req.method} ${req.url} ${res.statusCode}`;
  },
  customErrorMessage: (req, res, err) => {
    return `${req.method} ${req.url} ${res.statusCode} - ${err.message}`;
  },
  // 为每个请求生成 ID
  genReqId: (req) => req.headers['x-request-id'] || require('crypto').randomUUID(),
}));

// 路由中使用
app.get('/api/users', (req, res) => {
  req.log.info('开始查询用户'); // 自动携带请求上下文
  // ... 处理逻辑
  res.json({ users: [] });
});

const pino = require('pino');

// 生产环境：输出 JSON 到文件和 stdout
// 开发环境：使用 pino-pretty 美化输出
const logger = pino({
  level: process.env.LOG_LEVEL || 'info',
  transport: process.env.NODE_ENV !== 'production'
    ? { target: 'pino-pretty', options: { colorize: true, translateTime: 'SYS:HH:MM:ss' } }
    : undefined,
});

// 或使用多路输出
const transport = pino.transport({
  targets: [
    { target: 'pino-pretty', level: 'debug', options: { destination: 1 } }, // stdout
    { target: 'pino/file', level: 'info', options: { destination: './logs/app.log' } }, // 文件
  ],
});
const fileLogger = pino({ level: 'debug' }, transport);

npm install winston

const winston = require('winston');

const logger = winston.createLogger({
  level: process.env.LOG_LEVEL || 'info',
  format: winston.format.combine(
    winston.format.timestamp({ format: 'YYYY-MM-DD HH:mm:ss' }),
    winston.format.errors({ stack: true }),
    winston.format.json()
  ),
  defaultMeta: { service: 'my-app' },
  transports: [
    // 控制台输出
    new winston.transports.Console({
      format: process.env.NODE_ENV !== 'production'
        ? winston.format.combine(winston.format.colorize(), winston.format.simple())
        : winston.format.json(),
    }),
    // 文件输出
    new winston.transports.File({ filename: 'logs/error.log', level: 'error' }),
    new winston.transports.File({ filename: 'logs/combined.log' }),
  ],
});

// 使用
logger.info('用户登录', { userId: 123 });
logger.error('数据库错误', { error: err.message, stack: err.stack });

npm install winston-daily-rotate-file

const DailyRotateFile = require('winston-daily-rotate-file');

const transport = new DailyRotateFile({
  filename: 'logs/app-%DATE%.log',
  datePattern: 'YYYY-MM-DD',
  maxSize: '20m',       // 单文件最大 20MB
  maxFiles: '14d',      // 保留 14 天
  zippedArchive: true,  // 压缩旧文件
});

logger.add(transport);

// ✅ 好的结构化日志
logger.info({
  event: 'order_created',
  orderId: 'ORD-12345',
  userId: 'U-789',
  amount: 299.99,
  currency: 'CNY',
  items: 3,
  duration_ms: 45,
}, '订单创建成功');

// ❌ 不好的日志（字符串拼接）
logger.info(`用户 ${userId} 创建了订单 ${orderId}，金额 ${amount} 元`);

const { AsyncLocalStorage } = require('node:async_hooks');

const als = new AsyncLocalStorage();

function requestLogger(req, res, next) {
  const requestId = req.headers['x-request-id'] || crypto.randomUUID();
  const logger = baseLogger.child({ requestId, userId: req.user?.id });
  als.run({ logger, requestId }, () => {
    req.logger = logger;
    next();
  });
}

// 在任何地方获取当前请求的 Logger
function getLogger() {
  const store = als.getStore();
  return store?.logger || baseLogger;
}

// 业务代码中使用
async function processOrder(order) {
  const logger = getLogger();
  logger.info({ orderId: order.id }, '开始处理订单');
  // ...
  logger.info({ orderId: order.id }, '订单处理完成');
}