Evil::Metrics

This software is Work in Progress: features will appear and disappear, API will be changed, your feedback is always welcome!

Extensible solution for easy setup of monitoring in your Ruby apps.

Installation

Most of the time you don't need to add this gem to your Gemfile directly (unless you're only collecting your custom metrics):

gem 'evil-metrics'
# Then add monitoring system adapter, e.g.:
# gem 'evil-metrics-prometheus'

And then execute:

$ bundle

Usage

1. Declare your metrics:

   Evil::Metrics.configure do
     group :your_app
   
     counter   :bells_rang_count, "Total number of bells being rang"
     gauge     :whistles_active,  "Number of whistles ready to whistle"
     histogram :whistle_runtime,  "How long whistles are being active", unit: :seconds
   end
   

2. Access metric in your app and use it!

   def ring_the_bell(id)
     bell = Bell.find(id)
     bell.ring!
     Evil::Metrics.your_app_bells_rang_count.increment({bell_size: bell.size}, by: 1)
   end
   
   def whistle!
     Evil::Metrics.your_app_whistle_runtime.measure do
       # Run your code
     end
   end
   

3. Setup collecting of metrics that do not tied to specific events in you application. E.g.: reporting your app's current state

   Evil::Metrics.configure do
     # This block will be executed periodically few times in a minute
     # (by timer or external request depending on adapter you're using) 
     # Keep it fast and simple!
     collect do
       your_app_whistles_active.set({}, Whistle.where(state: :active).count
     end
   end
   

   1. See the docs for the adapter you're using
   2. Enjoy!

Roadmap (aka TODO or Help wanted)

• Ability to change metric settings for individual adapters

   histogram :foo, comment: "say what?" do
     adapter :prometheus do
       buckets [0.01, 0.5, …, 60, 300, 3600]
     end
   end

• Ability to route some metrics only for given adapter:

   adapter :prometheus do
     include_group :sidekiq
   end

Development

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.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/evil-metrics/evil-metrics.

License

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