mg-express

Express stuff used on all musicglue services

Automatically sets up logging, error handling, error reporting, and a bunch of other goodness.

Usage:

import setup from '@musicglue/mg-express';
import { UnprocessableEntityError } from '@musicglue/mg-express/lib/errors';

class UnmountableHorseError extends UnprocessableEntityError {
  constructor(msg) {
    super(msg);
    this.name = 'UnmountableHorseError';
  }
}

export default setup({
  name: 'horse service',
  bugsnag: 'abchorse',
  amazonJSON: true, // enable amazonian horses
  beforeHandlers: (app) => app.use(customHorseRelatedMiddleware()),
  handlers: (app, wrap) => {
    app.get('/horses', wrap(() =>
      Horses.list().then(horses => ({ payload: horses }))));
    app.post('/horses', wrap(({ body }) =>
      Horses.create(body).then(horse => ({ payload: horse, status: 201 }))));
    app.put('/horses/:horseId/mount', wrap(({ params }) => {
      throw new UnmountableHorseError('woah there!');
    }));
  },
});

options:

name - string

Name of the service. If provided, the service will serve this string on GET /.

defaultPort - number

Port to use if there's no process.env.PORT.

bugsnag - string

Bugsnag key. If provided and the service isn't in test mode, it'll setup bugsnag and attach it to the express app

bugsnagIgnore - Array - default []

A list of error names that bugsnag should ignore rather than report. e.g.

bugsnagIgnore: [
  'BadRequestError',
  'NotFoundError',
],

ping - string - default '/_____ping_____'

Ping URL. If provided, the service will serve OK on get requests to this route.

logFormat - string - default 'short'

Morgan log format. Morgan logging is disabled in test mode.

defaultContentType - string - default 'application/json'

If the content-type header isn't set, default it to this. Set to something falsey to disable.

amazonJSON - boolean - default false

Flag to turn on the amazon json middleware. If the user-agent looks like an amazon one, it sets the content-type header to 'application/json'.

consul - object - default null

Providing an object with key and url will bind a consul watcher to that subtree in a consul KV store, allowing for dynamic config with the config module

bodyParser - middleware - default bodyParser.json()

Body parsing middleware to use by default. Pass something falsey to disable body parsing.

errorHandler - middleware - default apiErrorHandler()

Middleware for handling errors.

before - function(app) - default () => null

Hook called before any default middleware are setup up, for custom things.

beforeHandlers - function(app) - default () => null

Hook called after the first set of middleware are set up, but before the handlers are attached.

handlers - function(app, wrap)

Hook called for attaching handlers. App is your express app, wrap is a useful function for wrapping handlers to hook into the rest of mg-express's goodness. Handlers wrapped with wrap should take one argument (the request object) and return a Promise of { payload: ?Object, status: ?number }. payload defaults to {}, status defaults to 200.

afterHandlers - function(app) - default () => null

Hook called after the handlers are attached, but before the error handling middleware.

after - function(app) - default () => null

Hook called after the app is finished being set up, immediately before it starts listening.

beforeListen - function() - default () => null

Hook called immediately before starting to listen

listen - function(app, port) - default (app, port) => app.listen(port)

Hook called instead of default listen directive to allow custom bindings, e.g. unix sockets

errors

import * from '@musicglue/mg-express/lib/errors';

mg-express has an automatically generated error class for every HTTP response code listed on http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml

These classes set the name and status required for compatibility with api-error-handler, the default error handler used by mg-express. To return one of these errors, throw it anywhere in your handler promise chain. If you want to return a non-200 status code without throwing one of these errors, have your handler promise resolve to an object with a status property with the status code you want to use.