EWL

EWL (express-winston-logger) provides common defaults for logging in an express application using winston. It is pre-configured with request tracing enabled and extends some of the features provided by express-winston, e.g. body blacklisting redaction.

Installation

yarn add ewl

Usage

import { Ewl } from 'ewl';

const ewl = new Ewl();
ewl.debug('This logs to the console by default.');

Basic Express Example

index.ts:

import { Application } from 'express';

import { ewl, initEwl } from './logger';

const app = express() as Application;
initEwl(app);

const port = 3000;
app.listen(port, () => {
  ewl.debug(`App: Listening on port ${port}!`);
});

logger/index.ts:

import { Application } from 'express';
import { Ewl, LogLevel } from 'ewl';

export let ewl: Ewl;

export function initEwl(app: Application): void {
  ewl = new Ewl({
    enableRequestLogging: true,
    environment: process.env.ENVIRONMENT || 'development',
    label: 'app',
    logLevel: (process.env.LOG_LEVEL as LogLevel) || 'error',
    useLogstashFormat: false,
    version: process.env.VERSION || 'unknown',
  });

  // Use context middleware to inject the request id.
  app.use(ewl.contextMiddleware);

  // Use request middleware to inject express metadata.
  app.use(ewl.requestMiddleware);
}

Basic NestJS Example

main.ts:

import { NestFactory } from '@nestjs/core';

import { Ewl, LogLevel } from 'ewl';

import { AppModule } from './app.module';

async function bootstrap() {
  const ewl = new Ewl({
    enableRequestLogging: true,
    environment: process.env.ENVIRONMENT || 'development',
    label: 'app',
    logLevel: (process.env.LOG_LEVEL as LogLevel) || 'error',
    useLogstashFormat: false,
    version: process.env.VERSION || 'unknown',
  });

  // Set the default NestJS logger, allowing EWL to be the proxy.
  const app = await NestFactory.create(AppModule, { logger: ewl });

  // Use context middleware to inject the request id.
  app.use(ewl.contextMiddleware);

  // Use request middleware to inject express metadata.
  app.use(ewl.requestMiddleware);

  ewl.debug('Starting application on localhost:3000');

  await app.listen(3000, 'localhost');
}

bootstrap();

Customizing express-winston Request Logger Middleware

const ewl = new Ewl({
  enableRequestLogging: false,
  requestLoggingOptions: {
    bodyBlacklist: ['accessToken', 'password', 'refreshToken'],
    colorize: true,
    expressFormat: true,
    headerBlacklist: ['cookie', 'token'],
    meta: true,
    metaField: 'express',
    requestWhitelist: ['body', 'headers', 'method', 'params', 'query', 'url'],
    responseWhitelist: ['body', 'headers', 'statusCode'],
    statusLevels: true,
  },
});

// Use request middleware to inject express metadata.
app.use(ewl.requestMiddleware);

License

MIT License

Contributing

Contributions are encouraged, please see further details below:

Pull Requests

Here are some basic rules to follow to ensure timely addition of your request:

1. Match coding style (braces, spacing, etc.).
2. If it is a feature, bugfix, or anything please only change the minimum amount of code required to satisfy the change.
3. Please keep PR titles easy to read and descriptive of changes, this will make them easier to merge.
4. Pull requests must be made against the main branch. Any other branch (unless specified by the maintainers) will get rejected.
5. Check for existing issues first, before filing a new issue.