Instrumenter

Instrumenter is a small gem that was created to allow logging with a single request id across multiple microservice backends. The idea here is that you set an X-Request-Id header on your edge, and this Gem will allow you to propagate that value through all your various services. For example:

1. CDN edge generates a request id (setting the X-Request-Id header)
2. The request goes to your first Rack microservice, which is a Rails app
3. The Rails app then calls another microservice. You add Instrumenter.instance.log_event(message) around your call to the second service, and set the X-Request-Id header on the call to the second service to the value of Instrumenter.instance.request_id
4. The second service receives the same value for X-Request-Id that was generated at the edge
5. The second (and any subsequent services) can continue to easily pass the same X-Request-Id header around, allowing you to trace a single request through multiple backends in your logs

Add this line to your application's Gemfile:

gem 'instrumenter'

And then execute:

$ bundle

Or install it yourself as:

$ gem install instrumenter

1. Load the Rack middleware

require 'instrumenter/instrumenter_middleware'
use Instrumenter::InstrumenterMiddleware

Lograge is recommended to get the most out of your logs on Rails

1. Load the Rack middleware in an initializer

require 'instrumenter/instrumenter_middleware'

Rails.configuration.middleware.tap do |rack|
  rack.use Instrumenter::InstrumenterMiddleware
end

2. Configure logging in environment / application.rb

module YourApp
  class Application < Rails::Application
    config.lograge.enabled = true
    config.lograge.formatter = Lograge::Formatters::Json.new
    config.lograge.custom_options = lambda do |event|
      { request_id: Instrumenter.instance.request_id }
    end
  end
end

1. Logging with your request id:

Instrumenter.instance.log_event("the wiglet is throbbling")

...gives you a log entry with: {"request_id":"d739ba90-0a91-46e7-846b-55580cbbe228","message":"the wiglet is throbbling"}

2. Use the request id in calls to other services

HTTParty.get(url, headers: { 'X-Request-Id': Instrumenter.instance.request_id })

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/mukaibot/instrumenter. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

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

Everyone interacting in the Instrumenter project’s codebases, issue trackers and mailing lists is expected to follow the code of conduct.