RequestQueueTime::Middleware

This gem gives us an indication of the time that a request/job is spent waiting in line to be processed and with that gauge we scale our ECS cluster tasks up and down. A lot of the logic was borrowed from Judoscales ruby gem, but at the time of writing the code we were unable to utilise Judoscale on ECS, however now that the gem is being extracted this is something that is now a product that they offer. However we are unsure about the financial gains that can be gained from using the service, vs our own solution.

Installation

Add this line to your application's Gemfile:

gem "request_queue_time", git: "https://github.com/Teamtailor/request_queue_time.git", tag: "v0.1.1"

And then execute:

$ bundle

Usage

The following environment variables are required for the metric that is reported to cloudwatch:

    ENV["DD_SERVICE"]
    ENV["DD_ENV"]

For example:

    ENV["DD_SERVICE"] = "teamtailor"
    ENV["DD_ENV"] = "eu-cyan"

For the Reporter to run, you need to have the following flag set as well:

    ENV["ECS_SETUP"]

If you want statsd measurements you need to have a the constant StatsdDdog defined.

A Railtie will insert the middleware first in your stack, but if there are issues or you need more control of the middleware placements you can use the configuration below:

If you want it first in the stack:

  Rails.configuration.middleware.insert_before 0, RequestQueueTime::Middleware

The following is required for the sidekiq portion to work though:

Rails.application.reloader.to_prepare do
...
  RequestQueueTime::AutoScalingMetrics::SidekiqReporter.enable if ENV["ECS_SETUP"]
end

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec or bundle exec rake 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.