Logr

Structured logging with metrics and events.

“Chaos was the law of nature; Order was the dream of man.” ― Henry Adams

Logr is a machine-friendly logging library for Ruby. It brings structure to what is usually just a messy stream of human-readable output, so you can later slice and dice your logs with ease. The library was designed with monitoring and analytics platforms in mind: bringing together events and metrics from your services and applications has never been easier.

Add this line to your application's Gemfile:

gem 'logr'

And then execute:

$ bundle

Or install it yourself as:

$ gem install logr

require 'logr'

class YourClass
  def self.logger
    @logger ||= Logr::Logger.new('your-logger-name')
  end

  .
  .
  .

  # A complex event that you want to monitor and has metrics associated
  YourClass.logger.event('event-name', arbitrary: 'context', add_what: 'you_need')
                  .monitored('Title of the event', 'A longer description.')
                  .metric('metric-name', 34.35)
                  .metric('loglines', 1234535, type: 'counter')
                  .info('Human readable old-school logline')

  # A simple logline
  YourClass.logger.warn('Oh-oh something is fishy!')
end

The first log line pretty printed:

{
  "timestamp":"2015-11-16 16:47:42 UTC",
  "level":"INFO",
  "logger":"your-logger-name",
  "event":{
    "name":"event-name",
    "arbitrary":"context",
    "add_what":"you_need",
    "monitored":true,
    "title":"Title of the event",
    "text":"A longer description."},
  "metrics":[
    {
      "name":"metric-name",
      "value":34.35,
      "type":"counter"
    },
    {
      "name":"loglines",
      "value":1234535,
      "type":"counter"
    }],
  "message":"Human readable old-school logline"
}

Log line with simple message:

{
  "timestamp":"2015-11-16 16:47:42 UTC",
  "level":"WARN",
  "logger":"your-logger-name",
  "message":"Oh-oh something is fishy!"
}

The default log level is INFO, you can overwrite this by providing the $LOG_LEVEL environmental variable or setting the log level in Logr::Logger.new. If you'd like to use $LOG_LEVEL for something else you can use another env variable name by passing the name to Logr::Logger.new as below:

Logr::Logger.new('your-logger-name', level: Logr.parse_level(var: 'YOUR_ENV_VARIABLE'))

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/sspinc/logr.

The gem is available as open source under the terms of the MIT License.