NewRelic::Starter

A library that provides a way to start the New Relic agent in a running process.

Add this line to your application's Gemfile:

gem 'new_relic-starter'

And then execute:

$ bundle

Or install it yourself as:

$ gem install new_relic-starter

The gem provides a Rack middleware which provides an endpoint to start the New Relic agent.

# config.ru
require 'new_relic/starter/rack'
use NewRelic::Starter::Rack

By default, the middleware uses the path /_new_relic/start:

$ curl -s http://localhost:8080/_new_relic/start
Started the New Relic agent.

You can specify the path of the endpoint using the path option:

# config.ru
require 'new_relic/starter/rack'
use NewRelic::Starter::Rack, path: '/foo'

If your Rack web server is a pre-forking web server and doesn't load the Rack application before forking, you will need to create a global latch before forking:

$latch = NewRelic::Starter::Latch.new

# config.ru
require 'new_relic/starter/rack'
use NewRelic::Starter::Rack, latch: $latch

Or you will need to create a latch backed by a file:

# config.ru
require 'new_relic/starter/rack'
use NewRelic::Starter::Rack, latch: NewRelic::Starter::Latch.new("/path/to/latch")

When a latch is backed by a file, you can also have the middleware start the New Relic agent by writing a single byte 1 to the file:

$ echo -n -e '\x1' > /path/to/latch

You can configure Rails to add the Rack middleware to the middleware stack with the default options by requiring new_relic/starter/rails.rb:

# Gemfile
gem 'new_relic-starter', require: 'new_relic/starter/rails'

If you want to specify options, you can manually configure the middleware:

# config/initializers/new_relic_starter.rb
Rails.application.config.middleware.use NewRelic::Starter::Rack, path: '/foo'

If your Resque worker forks before processing a job, you can add a hook to start the New Relic agent before forking:

starter = NewRelic::Starter.new(NewRelic::Starter::Latch.new("/path/to/latch"))
Resque.before_fork do
  starter.start(dispatcher: :resque, start_channel_listener: true)
end

Then you can have the starter start the New Relic agent by writing a single byte 1 to the file backing the latch:

$ echo -n -e '\x1' > /path/to/latch

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/kaorimatz/new_relic-starter.

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

The idea of starting the New Relic agent using the Rack middleware is borrowed from partiarelic.