log4js-node-marker

An extension to log4js-node to associate special markers with log messages. It's basically the log4js-node equivalent of log4j Markers.

Associating markers with log messages are a convenient way of being able to perform log message filtering, such as by using the MarkerSelector in combination with log4js-node-selectorlayout.

Usage

Install the package as a dependency of your project

npm install --save log4js-node-marker

Now you can log messages with markers as follows

const marker = SingletonMarkerContainer.getMarker('MyMarker');
const logger = log4js.getLogger();
logger.infoWithMarkers([marker], 'log message');

If you don't the look of the LEVELWithMarkers methods, a possible resolution is to write a wrapper type around log4js-node's Logger which calls the LEVELWithMarkers methods behind the scenes. We chose not to override the signature of the normal log4js-node info, debug, etc. methods to avoid breaking code that is already using log4js-node but wants to start using markers.

MarkerSelector

This package also includes a selector compatible with log4js-node-selectorlayout called the MarkerSelector. To use the selector, first add it to your log4js-node configuration. For example:

{
  "options": {
    "categories": {
      "default": {
        "appenders": [ "console" ],
        "level": "info"
      }
    },
    "appenders": {
      "console": {
        "type": "console",
        "layout": {
          "type": "selector",
          "defaultLayout": {
            "type": "pattern",
            "pattern": "%[[%d] [%p] [%c]%] - %m"
          },
          "selectors": [
            {
              "type": "marker",
              "matchMarkerName": "JSON",
              "layout": {
                "type": "pattern",
                "pattern": "%m"
              }
            }
          ]
        }
      }
    }
  }
}

Next, register the marker selector when you register the selector layout in your application. For example:

const selectorRegistrations = {
    'marker': markerSelectorFactory()
};
log4js.addLayout('selector', selectorLayoutRegistrar(selectorRegistrations));
log4js.configure(log4jsConfigObject);

License Information

Copyright 2018 Apex Learning Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.