Added initial version.

Author: Leonid Beder

.gitignore

@@ -0,0 +1,19 @@
+*.gem
+*.rbc
+.bundle
+.config
+coverage
+InstalledFiles
+lib/bundler/man
+pkg
+rdoc
+spec/reports
+test/tmp
+test/version_tmp
+tmp
+
+# YARD artifacts
+.yardoc
+_yardoc
+doc/
+dump.rdb

.rspec

@@ -0,0 +1,3 @@
+--colour
+--format progress
+--drb

.travis.yml

@@ -0,0 +1,3 @@
+rvm:
+  - 1.9.3
+  - 2.0.0

Gemfile

@@ -0,0 +1,6 @@
+source 'http://rubygems.org'
+
+gem 'rdoc'
+
+# Specify your gem's dependencies in rediska.gemspec
+gemspec

Gemfile.lock

@@ -0,0 +1,154 @@
+PATH
+  remote: .
+  specs:
+    health-monitor-rails (0.0.1)
+      rails (>= 3.2)
+
+GEM
+  remote: http://rubygems.org/
+  specs:
+    actionmailer (4.0.2)
+      actionpack (= 4.0.2)
+      mail (~> 2.5.4)
+    actionpack (4.0.2)
+      activesupport (= 4.0.2)
+      builder (~> 3.1.0)
+      erubis (~> 2.7.0)
+      rack (~> 1.5.2)
+      rack-test (~> 0.6.2)
+    activemodel (4.0.2)
+      activesupport (= 4.0.2)
+      builder (~> 3.1.0)
+    activerecord (4.0.2)
+      activemodel (= 4.0.2)
+      activerecord-deprecated_finders (~> 1.0.2)
+      activesupport (= 4.0.2)
+      arel (~> 4.0.0)
+    activerecord-deprecated_finders (1.0.3)
+    activesupport (4.0.2)
+      i18n (~> 0.6, >= 0.6.4)
+      minitest (~> 4.2)
+      multi_json (~> 1.3)
+      thread_safe (~> 0.1)
+      tzinfo (~> 0.3.37)
+    arel (4.0.2)
+    atomic (1.1.14)
+    builder (3.1.4)
+    celluloid (0.15.2)
+      timers (~> 1.1.0)
+    coderay (1.1.0)
+    connection_pool (1.2.0)
+    coveralls (0.7.0)
+      multi_json (~> 1.3)
+      rest-client
+      simplecov (>= 0.7)
+      term-ansicolor
+      thor
+    database_cleaner (1.2.0)
+    diff-lcs (1.2.5)
+    docile (1.1.3)
+    erubis (2.7.0)
+    hike (1.2.3)
+    i18n (0.6.9)
+    json (1.8.1)
+    mail (2.5.4)
+      mime-types (~> 1.16)
+      treetop (~> 1.4.8)
+    method_source (0.8.2)
+    mime-types (1.25.1)
+    minitest (4.7.5)
+    multi_json (1.8.4)
+    polyglot (0.3.3)
+    pry (0.9.12.6)
+      coderay (~> 1.0)
+      method_source (~> 0.8)
+      slop (~> 3.4)
+    rack (1.5.2)
+    rack-test (0.6.2)
+      rack (>= 1.0)
+    rails (4.0.2)
+      actionmailer (= 4.0.2)
+      actionpack (= 4.0.2)
+      activerecord (= 4.0.2)
+      activesupport (= 4.0.2)
+      bundler (>= 1.3.0, < 2.0)
+      railties (= 4.0.2)
+      sprockets-rails (~> 2.0.0)
+    railties (4.0.2)
+      actionpack (= 4.0.2)
+      activesupport (= 4.0.2)
+      rake (>= 0.8.7)
+      thor (>= 0.18.1, < 2.0)
+    rake (10.1.1)
+    rdoc (4.1.1)
+      json (~> 1.4)
+    redis (3.0.7)
+    redis-namespace (1.4.1)
+      redis (~> 3.0.4)
+    rediska (0.0.7)
+      redis (~> 3.0.0)
+    rest-client (1.6.7)
+      mime-types (>= 1.16)
+    rspec-core (2.14.7)
+    rspec-expectations (2.14.5)
+      diff-lcs (>= 1.1.3, < 2.0)
+    rspec-mocks (2.14.5)
+    rspec-rails (2.14.1)
+      actionpack (>= 3.0)
+      activemodel (>= 3.0)
+      activesupport (>= 3.0)
+      railties (>= 3.0)
+      rspec-core (~> 2.14.0)
+      rspec-expectations (~> 2.14.0)
+      rspec-mocks (~> 2.14.0)
+    sidekiq (2.17.4)
+      celluloid (>= 0.15.2)
+      connection_pool (>= 1.0.0)
+      json
+      redis (>= 3.0.6)
+      redis-namespace (>= 1.3.1)
+    simplecov (0.8.2)
+      docile (~> 1.1.0)
+      multi_json
+      simplecov-html (~> 0.8.0)
+    simplecov-html (0.8.0)
+    slop (3.4.7)
+    spork (0.9.2)
+    sprockets (2.10.1)
+      hike (~> 1.2)
+      multi_json (~> 1.0)
+      rack (~> 1.0)
+      tilt (~> 1.1, != 1.3.0)
+    sprockets-rails (2.0.1)
+      actionpack (>= 3.0)
+      activesupport (>= 3.0)
+      sprockets (~> 2.8)
+    sqlite3 (1.3.8)
+    term-ansicolor (1.3.0)
+      tins (~> 1.0)
+    thor (0.18.1)
+    thread_safe (0.1.3)
+      atomic
+    tilt (1.4.1)
+    timers (1.1.0)
+    tins (1.0.0)
+    treetop (1.4.15)
+      polyglot
+      polyglot (>= 0.3.1)
+    tzinfo (0.3.38)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  coveralls
+  database_cleaner
+  health-monitor-rails!
+  pry
+  rake
+  rdoc
+  rediska
+  rspec-rails
+  sidekiq
+  spork
+  sqlite3

LICENSE

@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright (c) 2014 Leonid Beder
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -0,0 +1,6 @@
+# health-monitor-rails
+
+[![Gem Version](https://badge.fury.io/rb/health-monitor-rails.png)](http://badge.fury.io/rb/health-monitor-rails)
+[![Build Status](https://travis-ci.org/lbeder/health-monitor-rails.png)](https://travis-ci.org/lbeder/health-monitor-rails)
+[![Dependency Status](https://gemnasium.com/lbeder/health-monitor-rails.png)](https://gemnasium.com/lbeder/health-monitor-rails)
+[![Coverage Status](https://coveralls.io/repos/lbeder/health-monitor-rails/badge.png)](https://coveralls.io/r/lbeder/health-monitor-rails)

Rakefile

@@ -0,0 +1,22 @@
+#!/usr/bin/env rake
+begin
+  require 'bundler/setup'
+rescue LoadError
+  puts 'You must `gem install bundler` and `bundle install` to run rake tasks'
+end
+
+APP_RAKEFILE = File.expand_path('../spec/dummy/Rakefile', __FILE__)
+load 'rails/tasks/engine.rake'
+
+Bundler::GemHelper.install_tasks
+
+require 'rspec/core/rake_task'
+
+Rake::TestTask.new(:test) do |t|
+  t.libs << 'lib'
+  t.libs << 'test'
+  t.pattern = 'test/**/*_test.rb'
+  t.verbose = false
+end
+
+task default: :test

app/controllers/health_controller.rb

@@ -0,0 +1,22 @@
+class HealthController < ActionController::Base
+  layout nil
+
+   # GET /health/check
+  def check
+    HealthMonitor.check!
+
+    render text: "Healh check has passed: #{Time.now.to_s(:db)}\n"
+  rescue Exception => e
+    render text: "Healh check has failed: #{Time.now.to_s(:db)}, error: #{e.message}\n",
+      :status => :service_unavailable
+  end
+
+  private
+  def process_with_silence(*args)
+    logger.quietly do
+      process_without_silence(*args)
+    end
+  end
+
+  alias_method_chain :process, :silence
+end

bin/rails

@@ -0,0 +1,9 @@
+#!/usr/bin/env ruby
+# This command will automatically be run when you run "rails" with Rails 3/4 gems installed from the
+# root of your application.
+
+ENGINE_ROOT = File.expand_path('../..', __FILE__)
+ENGINE_PATH = File.expand_path('../../lib/health_monitor/engine', __FILE__)
+
+require 'rails/all'
+require 'rails/engine/commands'

config/routes.rb

@@ -0,0 +1,3 @@
+HealthMonitor::Engine.routes.draw do
+  get :check
+end

health-monitor-rails.gemspec

@@ -0,0 +1,28 @@
+$:.push File.expand_path('../lib', __FILE__)
+require 'health_monitor/version'
+
+Gem::Specification.new do |s|
+  s.name        = 'health-monitor-rails'
+  s.version     = HealthMonitor::VERSION
+  s.platform    = Gem::Platform::RUBY
+  s.authors     = ['Leonid Beder']
+  s.email       = ['[email protected]']
+  s.license     = 'MIT'
+  s.homepage    = 'https://github.com/lbeder/health-monitor-rails'
+  s.summary     = 'xxx'
+  s.description = 'xxx.'
+
+  s.files = Dir['{app,config,db,lib}/**/*', 'MIT-LICENSE', 'Rakefile', 'README.md']
+  s.test_files = Dir['test/**/*']
+
+  s.add_dependency             'rails', '>= 3.2'
+  s.add_development_dependency 'sqlite3'
+  s.add_development_dependency 'rspec-rails'
+  s.add_development_dependency 'database_cleaner'
+  s.add_development_dependency 'spork'
+  s.add_development_dependency 'pry'
+  s.add_development_dependency 'coveralls'
+  s.add_development_dependency 'rake'
+  s.add_development_dependency 'rediska'
+  s.add_development_dependency 'sidekiq'
+end

lib/health-monitor-rails.rb

@@ -0,0 +1,4 @@
+require 'health_monitor/version'
+require 'health_monitor/engine'
+require 'health_monitor/configuration'
+require 'health_monitor/monitor'

lib/health_monitor/configuration.rb

@@ -0,0 +1,9 @@
+module HealthMonitor
+  class Configuration
+    attr_accessor :providers, :error_callback
+
+    def initialize
+      @providers = [:database]
+    end
+  end
+end

lib/health_monitor/engine.rb

@@ -0,0 +1,5 @@
+module HealthMonitor
+  class Engine < ::Rails::Engine
+    isolate_namespace HealthMonitor
+  end
+end

lib/health_monitor/monitor.rb

@@ -0,0 +1,27 @@
+require 'health_monitor/configuration'
+
+module HealthMonitor
+  extend self
+
+  attr_accessor :configuration
+
+  def configure
+    self.configuration ||= Configuration.new
+
+    yield configuration if block_given?
+  end
+
+  def check!
+    configuration.providers.each do |provider|
+      require "health_monitor/providers/#{provider}"
+
+      monitor = "HealthMonitor::Providers::#{provider.capitalize}".constantize.new
+      monitor.check!
+    end
+  rescue Exception => e
+    configuration.error_callback.call(e) if configuration.error_callback
+    raise
+  end
+end
+
+HealthMonitor.configure

lib/health_monitor/providers/cache.rb

@@ -0,0 +1,14 @@
+module HealthMonitor
+  module Providers
+    class Cache
+      def check!
+        time = Time.now.to_s
+
+        Rails.cache.write(:health, time)
+        fetched = Rails.cache.read(:health)
+
+        raise "different values (now: #{time}, fetched: #{fetched}" if fetched != time
+      end
+    end
+  end
+end

lib/health_monitor/providers/database.rb

@@ -0,0 +1,15 @@
+module HealthMonitor
+  module Providers
+    class DBException < StandardError; end
+
+    class Database
+      def check!
+        # Check connection to the DB:
+        query = "SELECT max(version, '0') FROM schema_migrations"
+        ActiveRecord::Base.connection.select_value(query).to_i
+      rescue => e
+        raise DBException.new(e.message)
+      end
+    end
+  end
+end