JSON Logger

Simple structured logging.

A subclass of Ruby's standard Logger which makes it easy to write structured data to your log files.

Basic Usage

instance = JsonLogger.factory(
  :device => '/tmp/test.log', # anything understood by Logger.new
  :level => Logger::INFO,
  :progname => 'foo'
)
instance.info('a simple message')
instance.error(:key => 'value', :other => [1,2,3])

Output in /tmp/test.log:

{
  "time":"2013-08-28T20:54:42.048Z",
  "progname":"foo",
  "level":"INFO",
  "level_id":1,
  "msg":"a simple message"
}
{
  "time":"2013-08-28T20:52:48.321Z",
  "progname":"foo",
  "level":"ERROR",
  "level_id":3,
  "data":"data",
  "other":[1,2,3]
}

Messages are actually written 1 per line (separated by a newline). I added the extra newlines here for readability.

Factory Defaults

You can set some defaults which will be added to every factory call. This works well from a Rails initializer, for example.

Subsequent calls to factory will always include these defaults, though they can be overridden if desired.

JsonLogger.factory_defaults = {
  :device => '/tmp/test.log',
  :level => Logger::INFO
}
instance = JsonLogger.factory(:progname => 'foo')
instance.info 'a simple message'

Presets

A factory call can include preset values which will be added to any log messages created by the returned instance.

instance = JsonLogger.factory(:progname => 'foo', :presets => {:a => 'b', :c => 'd'})
instance.error('hello')

Output:

{
  "time":"2013-08-28T20:52:48.321Z",
  "progname":"foo",
  "level":"ERROR",
  "level_id":3,
  "a":"b",
  "c":"d",
  "msg":"hello",
}

Development

CI

This application uses Github Actions for CI.

Copyright

Copyright (c) 2013 Alex Dean. See LICENSE.txt for further details.

Tag for hackweek glossary:

Simple structured logging. A subclass of Ruby's standard Logger which makes it easy to write structured data to your log files.

Vertical: Tools

Related links: https://github.com/tedconf/json_logger