ewl

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:

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