A super simple Sinatra API to expose the status of a unit / job within a CoreOS cluster.

coffa.rb

require 'sinatra/base'
require 'etcd'

class Coffa < Sinatra::Base
  get '/units/:name' do
    begin
      payload = fetch_payload(params[:name])
      status 200
      payload.value
    rescue Etcd::KeyNotFound
      status 404
    end
  end

  get '/status/:name' do
    begin
      payload = fetch_job(params[:name])
      status 200
      payload.value
    rescue Etcd::KeyNotFound
      status 404
    end
  end

  private

  def etcd
    @etcd ||= Etcd.client(host: ENV.fetch("ETCD_HOST", '127.0.0.1'), port: 4001)
  end

  def fetch_payload(name)
    etcd.get("/_coreos.com/fleet/payload/#{name}.service")
  end

  def fetch_job(name)
    etcd.get("/_coreos.com/fleet/job/#{name}.service")
  end
end

coffa_spec.rb

ENV['RACK_ENV'] = 'test'
$:.push(File.expand_path(File.join(__FILE__, '..', '..')))

require 'spec_helper'
require 'rspec'
require 'coffa'
require 'rack/test'

describe 'Coffa' do
  include Rack::Test::Methods

  def app
    Coffa
  end

  describe 'units' do
    context 'not found' do
      before do
        stub_request(:get, "http://127.0.0.1:4001/v2/keys/_coreos.com/fleet/payload/no.service").
           with(:headers => {'Accept'=>'*/*', 'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3', 'User-Agent'=>'Ruby'}).
           to_return(:status => 404, :body => '{"errorCode":100,"message":"Key not found","cause":"/_coreos.com/fleet/payload/no.service","index":6812}', :headers => {})
      end

      it 'handles 404' do
        get '/units/no'
        expect(last_response).to be_not_found
      end
    end

    context 'found' do
      before do
        stub_request(:get, "http://127.0.0.1:4001/v2/keys/_coreos.com/fleet/payload/sesame.service").
           with(:headers => {'Accept'=>'*/*', 'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3', 'User-Agent'=>'Ruby'}).
           to_return(:status => 200, :body => '{"action":"get","node":{"key":"/_coreos.com/fleet/payload/sesame.service","value":"{\"Name\":\"sesame.service\",\"Unit\":{\"Contents\":{\"Install\":{\"WantedBy\":\"local.target\"},\"Service\":{\"ExecStart\":\"/usr/bin/docker run --rm -p 8080:9292 --name sesame b17s/sesame:latest\",\"ExecStartPre\":\"/usr/bin/docker pull b17s/sesame\",\"ExecStop\":\"/usr/bin/docker kill sesame\",\"User\":\"core\"},\"Unit\":{\"After\":\"docker.service\",\"Description\":\"Sesame\",\"Requires\":\"docker.service\"}}}}","modifiedIndex":5354,"createdIndex":5354}}', :headers => {})
      end

      it 'has units endpoint' do
        get '/units/sesame'
        expect(last_response).to be_ok
      end
    end
  end


  describe 'status' do
    context 'not found' do
      before do
        stub_request(:get, "http://127.0.0.1:4001/v2/keys/_coreos.com/fleet/job/no.service").
           with(:headers => {'Accept'=>'*/*', 'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3', 'User-Agent'=>'Ruby'}).
           to_return(:status => 404, :body => '{"errorCode":100,"message":"Key not found","cause":"/_coreos.com/fleet/job/no.service","index":6902}', :headers => {})
      end

      it 'handles 404' do
        get '/status/no'
        expect(last_response).to be_not_found
      end
    end

    context 'found' do
      before do
        stub_request(:get, "http://127.0.0.1:4001/v2/keys/_coreos.com/fleet/job/sesame.service").
           with(:headers => {'Accept'=>'*/*', 'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3', 'User-Agent'=>'Ruby'}).
           to_return(:status => 200, :body => '{"action":"get","node":{"key":"/_coreos.com/fleet/job/sesame.service","dir":true,"nodes":[{"key":"/_coreos.com/fleet/job/sesame.service/object","value":"{\"Name\":\"sesame.service\",\"JobRequirements\":{},\"Payload\":{\"Name\":\"sesame.service\",\"Unit\":{\"Contents\":{\"Install\":{\"WantedBy\":\"local.target\"},\"Service\":{\"ExecStart\":\"/usr/bin/docker run --rm -p 8080:9292 --name sesame b17s/sesame:latest\",\"ExecStartPre\":\"/usr/bin/docker pull b17s/sesame\",\"ExecStop\":\"/usr/bin/docker kill sesame\",\"User\":\"core\"},\"Unit\":{\"After\":\"docker.service\",\"Description\":\"Sesame\",\"Requires\":\"docker.service\"}}}},\"State\":null}","modifiedIndex":6638,"createdIndex":6638},{"key":"/_coreos.com/fleet/job/sesame.service/target","value":"398bd61a-0e09-4797-8929-f6d6ceb2c767","modifiedIndex":6646,"createdIndex":6646}],"modifiedIndex":6638,"createdIndex":6638}}', :headers => {})
      end

      it 'has status endpoint' do
        get '/status/sesame'
        expect(last_response).to be_ok
      end
    end
  end
end

config.ru

#!/usr/bin/env ruby

require 'rubygems'
require 'bundler/setup'
$: << File.expand_path(File.dirname(__FILE__))
require 'coffa'

use Coffa
run Sinatra::Application

Gemfile

source "https://rubygems.org"

gem 'sinatra'
gem 'etcd'

group :development do
  gem 'rake'
  gem 'rspec'
  gem 'rack-test'
  gem 'shotgun'
  gem 'webmock'
end

spec_helper.rb

require 'pathname'
$: << Pathname.new(__FILE__).parent.parent.to_s
require 'coffa'
require 'webmock/rspec'

RSpec.configure do |config|
  # Use color in STDOUT
  config.color_enabled = true

  # Use color not only in STDOUT but also in pagers and files
  config.tty = true

  # Use the specified formatter
  config.formatter = :documentation # :progress, :html, :textmate

  # Rspec 3 forward compatibility
  config.treat_symbols_as_metadata_keys_with_true_values = true
end