log4js-json-layout

A slim and easy to use JSON layout for log4js-node.

Installation

npm install log4js-json-layout --save

Example Output

Output:

{"startTime":"2017-07-27T00:01:05.175Z","categoryName":"/path/to/file/redis-client.js","level":"DEBUG","data":"Connection to Redis successful!"}

Usage

Set the layout type to json.

Each log object contains the following properties:

startTime - time in ISO 8601 format
categoryName - specified when log4js is initialized
data - if the log message is a string, otherwise omitted
level - level in human readable format
source - if provided, will be included

Additional properties can be specified as extra arguments of object type during invocation of log function. Static or constant properties can be specified using the static config option.

Options

type - string, always json
source - optional string, just sets the property source. Example value: development
include - array of properties to include in the log object
colors - boolean; off by default. If set to true, colorizes the output using log4js default color scheme based on log level. Useful for development, do not use for storing logs
static - object, name value pairs of this object are added to output
dynamic - object, where each value is a no-argument function that must return a string/number/boolean. The key and the function's return value are added to the output

Example Config

const log4js = require('log4js');
const jsonLayout = require('log4js-json-layout');

log4js.addLayout('json', jsonLayout);

Minimal:

appenders = [{
  type: 'console',
  layout: {
    type: 'json',
  }
}];

More options:

appenders = [{
  type: 'console',
  messageParam: 'msg',
  layout: {
    type: 'json',
    source: 'development',
    static: {
      appName: 'mysuperbapp'
    },
    dynamic: {
      transactionId: function() {
        return 'tx-id'; // string
      },
      isAdmin: function() {
        return 1>0; // boolean
      },
      countLogin: function() {
        return 20; // number
      }
    },
    include: ['startTime', 'categoryName'],
  }
}];

const logger = log4js.getLogger('info');

logger.info('Test log');