How to Configure Monolog to Email Errors

New in version 3.6: Support for emailing errors using Symfony mailer was added in MonologBundle 3.6.

Monolog can be configured to send an email when an error occurs within an application. The configuration for this requires a few nested handlers in order to avoid receiving too many emails. This configuration looks complicated at first but each handler is fairly straightforward when it is broken down.

The main handler is a fingers_crossed handler which means that it is only triggered when the action level, in this case critical is reached. The critical level is only triggered for 5xx HTTP code errors. If this level is reached once, the fingers_crossed handler will log all messages regardless of their level. The handler setting means that the output is then passed onto the deduplicated handler.

Tip

If you want both 400 level and 500 level errors to trigger an email, set the action_level to error instead of critical. See the code above for an example.

The deduplicated handler keeps all the messages for a request and then passes them onto the nested handler in one go, but only if the records are unique over a given period of time (60 seconds by default). Duplicated records are discarded. Adding this handler reduces the amount of notifications to a manageable level, specially in critical failure scenarios. You can adjust the time period using the time option:

The messages are then passed to the symfony_mailer handler. This is the handler that actually deals with emailing you the error. The settings for this are straightforward, the to and from addresses, the formatter, the content type and the subject.

You can combine these handlers with other handlers so that the errors still get logged on the server as well as the emails being sent:

This uses the group handler to send the messages to the two group members, the deduplicated and the stream handlers. The messages will now be both written to the log file and emailed.