@cork-labs/http-middleware-logger NPM

HTTP Middleware Logger

Express middleware, adds a child logger to each request.

Getting Started

npm install --save @cork-labs/http-middleware-logger

const bunyan = require('bunyan');
const Logger = require('@cork-labs/monkfish-adapter-logger').Logger;

// your application setup
const logger = Logger.createLogger({ name: 'my-app', streams: [{ type:'console' }] });
const httpLogger = require('@cork-labs/http-middleware-logger');
const options = {};
this._express.use(httpLogger(config, logger));
// use a middleware such as onHeaders to log responses
this._express.use((req, res, next) => {
  onHeaders(res, () => res.log());
  next();
});

// your route
app.get('/path', (req, res, next) => {
  req.logger.info(data, 'message');
})

Provide an instance of @cork-labs/monkfish-adapter-logger.

It supports:

child loggers (child contexts)
multiple streams at once (e.g.: console, bunyan, files, ...)

API

A child logger is created per request, and trace information is added to the logger.

The request is immediately logged.

> my-app | Thu, 10 Jan 2019 23:51:35 GMT | INFO | HttpApi::request()
  trace: {
    "uuid": "5b42547e-bd2f-4090-896c-18edfd79f39b",
    "current": "5efc8d65-2dd3-458c-8a46-96aa37985a4f"
  }
  --
  request: {
    "method": "GET",
    "path": "/account/5a9578f91e0d4724ed57ffe3"
  }

The child logger is exposed in req.logger and you can log further messages.

All messages contain the same trace object plus whatever data you provide to them.

16:29:19.279Z  INFO az.auth: Service::handle()
  trace: {
    "uuid": "5b42547e-bd2f-4090-896c-18edfd79f39b",
    "current": "5efc8d65-2dd3-458c-8a46-96aa37985a4f"
  }
  --
  event: {
    "type": "account.get",
    "params": {
      "id": "5a9578f91e0d4724ed57ffe3"
    }
  }

The essential monkfish-adapter-logger API:

req.logger.child(data = {}) returns a new logger, containing all the parent context plus the provided optional data
req.logger.set(key, value = undefined) - adds key to context data (avoid adding objects, keep it flat!)
req.logger.debug('message', data = {}) - logs debug level message, with adittional data (optional)
req.logger.info('message', data = {}) - same, info level
req.logger.warn('message', data = {}) - same, warning level
req.logger.error('message', data = {}, err = ...) - same, error level, plus optional error (ideally a subclass of Error)
req.logger.flat(prefix = '', obj) flattens the object for logging

res.log()

When the response is sent, invoke res.log().

You can use a middleware such as onHeaders to be notified when the response is sent.

this._express.use(httpLogger(config, logger));
// use a middleware such as onHeaders to log responses
this._express.use((req, res, next) => {
  onHeaders(res, () => res.log());
  next();
});

The response log contains a number of configurable.

The severity of this message can be configured via options.severityMap.

> my-app | Thu, 10 Jan 2019 23:51:35 GMT | INFO | HttpApi::response()
  trace: {
    "uuid": "5b42547e-bd2f-4090-896c-18edfd79f39b",
    "current": "5efc8d65-2dd3-458c-8a46-96aa37985a4f"
  }
  --
  response: {
    "status": 200
  }
  --
  timing: {
    "total": 20,
    "routed": 5,
    "handled": 15
  }

Configuration

The middleware can be configured via an options object when calling its factory function.

const options = {
  headers: {
    message: 'http.request.received'
  }
};
app.use(httpLogger(options));

requestMessage (default: 'http request')

requestKey (default: 'request')

requestFields (default: { method: 'method', path: 'path' })

responsetMessage (default: 'http response')

responseKey (default: 'response')

responseTimingKey (default: 'timing')

responseFields (default: { status: 'statusCode' })

traceKey (default: 'trace')

traceFields (default: { uuid: 'uuid', current: 'path' })

severityMap (default: { })

Develop

# lint and fix
npm run lint

# run test suite
npm test

# lint and test
npm run build

# serve test coverage
npm run coverage

# publish a minor version
node_modules/.bin/npm-bump minor