Logstash json event layout for Log4J2

The goal is to be reasonably performant and (near) garbage-free.

The layout lacks many options, but the defaults should produce sane messages conforming to the Logback LoggingEvent fields. Each message is separated by a newline.

The layout is modelled after GelfLayout.

Usage

For printing to standard out in a format suitable for eg. fluentd:

<Appenders>
    <Console name="console" target="SYSTEM_OUT">
        <LogstashLayoutV1 host="someserver" includeStacktrace="true" includeThreadContext="false"/>
    </Console>
</Appenders>

Supported parameters are:

• host: The hostname, appears in the source_host field. Optional, defaults to the local hostname.
• includeStacktrace: Enable logging of stacktraces of logged exceptions. Optional, defaults to true.
• includeThreadContext: Enable logging of the thread context. Optional, defaults to true.
• includeTimestamp: Enable logging of the @timestamp field. Optional, defaults to true.