Configure log4j2 with yaml, json and xml for different message layout of different log levels

areadme.md

This shows roughly similar configurations to distinguish message formats for different error levels in log4j version 2. I believe the yaml configuration is the easiert to read and maintain.

log4j.json

{
  "status": "info",
  "appenders": {
   "Console": [{
           "name": "info",
           "PatternLayout": { "pattern": "inf %5p - %m%n" } },
          {"name": "err",
           "PatternLayout": { "pattern": "err %5p %logger %m %l%n" } }
   ]},
  "loggers": {
    "root": { "level": "off" },
    "logger": [
        {
            "name": "a",
            "level": "all",
            "appender-ref": [ { "ref": "info" },
           { "ref": "err", "level":"error"}
            ]
        },
        {
            "name": "b",
            "level": "off",
            "appender-ref": { "ref": "err" }
        }
    ]}
}

log4j.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="info" strict="true" name="XMLConfigTest"
               packages="org.apache.logging.log4j.test">
    <Appenders>
        <Appender type="Console" name="short">
            <Filter type="ThresholdFilter" level="error"/>
            <Layout type="PatternLayout" pattern="short %p %m%n"/>
        </Appender>
        <Appender type="Console" name="long">
            <Layout type="PatternLayout" pattern="long  %p %m%n"/>
            <Filter type="ThresholdFilter" level="error" onMatch="deny" onMismatch="accept"/>
        </Appender>
    </Appenders>

    <Loggers>
        <Logger name="a" level="debug" additivity="false">
            <AppenderRef ref="short" level="warn"/>
            <AppenderRef ref="long"/>
        </Logger>

        <Logger name="b" level="off" additivity="false">
            <AppenderRef ref="long"/>
        </Logger>

        <Root level="trace">
            <AppenderRef ref="long"/>
        </Root>
    </Loggers>

</Configuration>

log4j.yaml

status: info # log level of log4j itself when configuring
appenders: # it is a map of appender types
    Console: # appender type - a list of appender configurations
      - name: info # name to use in logger references
        ThresholdFilter: # filters out error messages
          level: error
          onMatch: deny # hide error level
          onMismatch: accept # show others
        PatternLayout: { pattern: "inf %5p %m%n" } # short pattern
      - name: err # the next list entry is indivcated by the dash
        ThresholdFilter:
          level: error # show for error
        PatternLayout: { pattern: "err %p %l %msg%n" } # pattern with source code location (%l}
loggers:
    root: {level: error} # like the default, but to keep log4j from complaining # level off does not work in R2.02
    logger: # logger is a list of loggers configurations
      - name: a
        level: trace # general level for this logger, further restricted in the appenders
        appender-ref: # a list of appenders. All messages
          - ref: err
          - ref: info
      - name: b # another logger
        level: info
        appender-ref:
          - ref: err
          - ref: info

yaml format is better

With xml I know what I can put in the xml because there is an xsd. I don't have to search endlessly for examples, documentation...