@english-learning/logger

Shared logger and HTTP request/response logging middleware for the English Learning platform (NestJS services).

Features

• Winston-based AppLogger with console + daily rotate file output (JSON), configurable via env.
• Request/response middleware with trace ID (UUID v4) propagation and status-based log levels.
• Body logging with redaction for sensitive keys (password/token/cookies) and optional size cap.
• Trace ID header x-trace-id added to responses and forwarded through the gateway.

Usage (Nest bootstrap)

import { AppLogger, createRequestLoggerMiddleware } from '@english-learning/logger';

async function bootstrap() {
  const appLogger = new AppLogger();
  const app = await NestFactory.create(AppModule, { logger: appLogger });
  app.useLogger(appLogger);

  app.use(
    createRequestLoggerMiddleware({
      logger: appLogger,
      bodyMax: Number(process.env.LOGGER_BODY_MAX ?? '0'),
    }),
  );
}

Config (env)

• LOGGER_LEVEL (default info)
• LOGGER_DIR (default logs)
• LOGGER_FILENAME (default app-%DATE%.log)
• LOGGER_MAX_SIZE (default 10m)
• LOGGER_MAX_FILES (default 14d)
• LOGGER_BODY_MAX (default 0 unlimited) — truncate logged body when set.
• LOGGER_REDACT_KEYS (comma list, default: password, token, access_token, refresh_token, cookie, cookies)

Body redaction: password/token/cookie fields are logged as [redacted len=NN preview=abc...xyz] (first 3 + last 3 chars, plus size). Binary buffers log as [buffer len=N].

Publish

1. Build: pnpm install then pnpm --dir packages/logger build
2. (Optional) Pack: pnpm --dir packages/logger pack
3. Publish to npm (public): npm publish
4. Verify: npm view @english-learning/logger version

Install from npm

pnpm add @english-learning/logger

Notes

• Trace ID header: x-trace-id is generated if absent and forwarded downstream.
• Middleware logs request/response bodies; set LOGGER_BODY_MAX to cap size if payloads are large.
• Validation errors remain 422; middleware logs once per request with the corresponding trace ID.