Log straight to elasticsearch

Great idea, writing log to file is quite slow.

But using the Symfony bundle seems a bit overkill, no ? The logging process should the lighter possible, just using a simple guzzle call, a non blocking one if possible (https://drupal.stackexchange.com/questions/296743/non-blocking-http-requ...).

The whole point to using Symfony in Drupal is to avoid duplicating effort and then having to maintain more code. Although the package may be large, most isn't used and thus not loaded, so should not be a problem. Disk space is cheap, developer time is not ;-)