OpenTracing Rails Instrumentation

This gem is an attempt to introduce OpenTracing instrumentation into Rails. It's in a very early stage.

The following instrumentation is supported:

• ActionDispatch - The library introduces a rack middleware, which is intended to be used together with rack-tracer, to generate more informative operation names based on information supplied by ActionDispatch.
• ActiveRecord - The library hooks up into Rails, and instruments all ActiveRecord query.

Installation

Add this line to your application's Gemfile:

gem 'rails-tracer'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rails-tracer

ActionDispatch

When you use rack-tracer, the generated operation name corresponds to the request's http method e.g. GET, POST etc. It's not perfect. You need to dig into the trace to understand with what url it's related.

The rails-tracer introduces another rack middleware, which is intended to be used together with rack-tracer, to generate more informative operation names in the form ControllerName#action.

Usage

require 'rack/tracer'
require 'rails/tracer'

Rails.configuration.middleware.use(Rack::Tracer)
Rails.configuration.middleware.insert_after(Rack::Tracer, Rails::Rack::Tracer)

ActiveRecord

The library hooks up into Rails using ActiveSupport::Notifications, and instruments all ActiveRecord query.

Usage

Auto-instrumentation example.

require 'rails/tracer'

ActiveRecord::Tracer.instrument(tracer: OpenTracing.global_tracer, active_span: -> { OpenTracing.global_tracer.active_span })

There are times when you might want to skip ActiveRecord's magic, and use connection directly. Still the library can help you with span creation. Instead of auto-instrumenting you can manually call ActiveRecord::Tracer.start_span as shown below.

def q(name, sql)
  span = ActiveRecord::Tracer.start_span(name, 
                                          tracer: OpenTracing.global_tracer,
                                          active_span: -> { OpenTracing.global_tracer.active_span },
                                          sql: sql)
  ActiveRecord::Base.
    connection.
    raw_connection.
    query(sql).
    each(as: :hash)
ensure
  span&.finish
end

q("FirstUser", "SELECT * FROM users LIMIT 1")

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/iaintshine/ruby-rails-tracer. 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.