GELF appender for log4js

npm install log4js-gelf
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GELF format appender for log4js-node. Requires log4js version 0.7 or later to use.


npm install log4js log4js-gelf


Once installed, configure it as part of the log4js initialisation:

var log4js = require('log4js');
    appenders: {
        "gelf": { 
            type: "log4js-gelf",
            host: "gelf.host",
            port: 1234,
            hostname: "node-server",
            facility: "myapp"
    categories: {
        "default": { level: "DEBUG", appenders: [ "gelf" ] }

The GELF appender will log events via UDP to the configured server.


  • host (String) - hostname of your GELF/graylog2 server where the log messages will be sent (default: localhost)
  • port (Number) - port number your GELF server is listening on (default: 12201)
  • hostname (String) - hostname of the running app (default: os hostname)
  • facility (String) - the facility to log to (default: nodejs-server)
  • customFields (Object) - a set of keys and values to add to all log messages. Keys should start with underscore, otherwise they will be ignored. These values can be overridden by providing the first argument to logger.debug (etc) as an object with a GELF property. e.g.

    logger.info({ GELF: { _extra: "thing" } }, "rest of log
  • layout (Object) - log4js standard layout config (default: message pass through layout)


The GELF appender was originally contributed to log4js by Arif Amirani.


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