The default JSON Lines formatter. This formatter formats log records as JSON objects, one per line, which is a common format for log files. It looks like this:
{"@timestamp":"2023-11-14T22:13:20.000Z","level":"INFO","message":"Hello, world!","logger":"my.logger","properties":{"key":"value"}}
You can customize the output by passing options to getJsonLinesFormatter. For example, you can change the category separator, the message format, and how the properties are formatted.