Logdna logger + serverless functions

Love the LogDNA platform so far! I have a question about some pitfalls and best practices when using the logger in combination with the serverless functions - in my particular case it's the Google Cloud Functions platform + Express.js.

The main issue that worries me is that the RE of a Cloud Function can be terminated before the background tasks are finished (see this and this, also here's a little bit more elaborate version). As per the logdna/logger-node's best practices example in the docs, the client is optimised for high throughput, and it is advised to send a bunch of logs together instead of sending them individually. But I don't think I should rely on SIGTERM or SIGINT events in a serverless environment, or at least I'm not sure if it's a good practice.

Here's the best I could come up with in order to make sure the logs are getting sent to the LogDNA servers:

// utility function for sending the response
const sendJson = async (res: express.Response, json: any): Promise<void> => {
  logdnaLogger.flush()
  await once(logdnaLogger, 'cleared')
  res.json(json) // everything after this line has no guarantee to be executed
}

// somewhere far, far away...
const router = Router()

router.get(
  '/helloworld',
  async (req, res) => {
    const { uid } = getUser(req)

    const groups = await groupsRepo.findByUserId(uid)
    const sortedGroups = _(groups).sortBy(g => g.name)
    // use this helper function in order to send the logs instead of res.json(sortedGroups)
    await sendJson(res, sortedGroups)
  })

TBF I didn't test this solution yet, but still I'd be glad to hear other opinions on the topic.

logdna / logger-node

Logdna logger + serverless functions #62