We were having a discussion at work about logging:

I was thinking about the pros and cons of adding stack traces to log metadata last week, and the difference between the messages we log for helping operate the system and the messages which get presented to the real end user (see kevlinhenney on twitter for endless examples of diagnostics ending up in user interfaces).I was wondering about having a function to automatically bundle stacktrace information into a log message so we could do something like:

# stripped down code to handle a failure # e.g. {:error, posix} = File.open(filename)
message = "Failed to open #{filename}" #{:file.format_error(posix)}
OurLogger.error(message)
{:error, message}

And OurLogger could massage and add stacktrace: Process.info(self(), :current_stacktrace) to the metadata. The log formatter could then display stack traces for error and higher?Then the application sending a result to the eventual human would have to make sure it presented an appropriate message for the user.

This sounds…possible, but it feels like it would be very expensive to achieve. Obviously, we’d never implement this without benchmarking getting a stacktrace, but what I wonder is whether cost is that high?

If it’s low, would there be a reason to add this to Elixir’s logger by default?