How to exclude a log4js category from being logged to the default appenders

Question

I'm using node-log4js. (it's log4JS, not log4J!) I thought of the loggers 'categories' to be just like the Strings you put in Log4J into the constructor of a logger (normally you put your fqn class name there), so that log4j can put logged things to the right location.

I got the following config:

{
    "appenders": [
        {
            "type": "console",
        },
        {
            "type": "file",
            "absolute": true,
            "filename": "/tmp/app.log",
            "maxLogSize": 20480,
            "backups": 10     
        },
        {
            "type": "console",
            "category": "app.access"
        }
    ]
}

The desired behaviour would be that all "app.access" stuff only goes to the last appender (which is, at the moment, the console, too, but could change in future). At the moment, all loggings with the category 'app.access' will be logged twice to console and once to file.

Is there a way to give those other two appenders a "all but app.access"-category? How?

Thank you very much in advance

Answer 1

I had a similar requirement. I wanted to exclude a bunch of categories from the console logger.

I wrote something based on the logLevelFilter, which I called categoryFilter.

categoryFilter.js:

"use strict";
var log4js = require('log4js');

function categoryFilter (excludeCategories, appender) {
  return function(logEvent) {
    if (excludeCategories.every(function(x){return (x!=logEvent.category);})) {
      appender(logEvent);
    }
  };
}

function configure(config) {
  log4js.loadAppender(config.appender.type);
  var appender = log4js.appenderMakers[config.appender.type](config.appender);
  return categoryFilter(config.exclude, appender);
}

exports.appender = categoryFilter;
exports.configure = configure;

To use it, I have this snippet near the beginning of my app:

  var log4js = require('log4js');
  log4js.loadAppender('categoryFilter',require('./src/categoryFilter'));
  log4js.configure('log4js-conf.js');

My configuration file has the following:

{
  "appenders": [
    {
      "type": "file",
      "filename": "logs/logfile.log",
      "maxLogSize": 20480,
      "backups": 3
    },
    {
      "type": "categoryFilter",
      "exclude":["results"],
      "appender":{
        "type": "console"
      }
    },
  ],
  "replaceConsole":true
}

I'd be interested in your thoughts.

Answer 2

I faced a similar problem and here's how I resolved it - using the levels. Used the following config file:

{
    "appenders": [
        {
            "type": "logLevelFilter",
            "level": "INFO",
            "appender": { 
                "type": "console",
                "layout": {
                    "type": "colored",
                    "pattern": "[%d] %-5p <%c> %m"
                }
            }
        },
        {
            "type": "console",
            "layout": {
                "type": "messagePassThrough"
            },
            "category": "raw"
        }
    ]
}

The use 2 different log4js instances as follows:

var path = require('path');
var log4js = require('log4js');
log4js.configure('log4js.json');
var log = log4js.getLogger(path.basename(__filename));
var raw = log4js.getLogger('raw');

In your code use log.info(), log.warn(), log.error() or log.fatal() to have standard logs such as:

[2015-01-12 19:37:19.931] [INFO] app.js - app started
[2015-01-12 19:38:52.484] [ERROR] other.js - Error. failed to open file

Same logs above would look like this using raw.trace():

app started
Error. failed to open file

I'm using it to highlight different situations in the console. It is important to me to have it look totally different so I will notice these events. But when it is logged to a file, I don't mind if it has the timestamp (since it actually helps when looking back in time). Therefore I also have the following appender in the log4js.json file:

{
    "type": "file",
    "filename": "app.log",
    "maxLogSize": 1048576,
    "backups": 10,
    "layout": {
        "type": "pattern",
        "pattern": "[%d] %-5p <%c> %m"
    }
}

Hope this help! :)

Answer 3

Just assign top two appenders to a different category than "app.access" and use that category in getLogger.