flawless victory

.gitignore

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+pkg

LICENSE

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+The MIT License
+
+Copyright (c) GitHub, Inc
+
+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

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+# RackMonitor
+
+Some tiny Rack apps for monitoring Rack apps in production.
+
+* RackMonitor::RequestStatus - Adds a status URL for health checks.
+* RackMonitor::RequestHostname - Shows which what code is running on
+  which node for a given request.
+* RackMonitor::ProcessUtilization - Tracks how long Unicorns spend
+  processing requests.  Optioanally sends metrics to a StatsD server.
+
+This code has been extracted from GitHub.com and is used on
+http://git.io currently.
+

Rakefile

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+require 'rubygems'
+require 'rake'
+require 'date'
+
+#############################################################################
+#
+# Helper functions
+#
+#############################################################################
+
+def name
+  @name ||= Dir['*.gemspec'].first.split('.').first
+end
+
+def version
+  line = File.read("lib/#{name}.rb")[/^\s*VERSION\s*=\s*.*/]
+  line.match(/.*VERSION\s*=\s*['"](.*)['"]/)[1]
+end
+
+def date
+  Date.today.to_s
+end
+
+def rubyforge_project
+  name
+end
+
+def gemspec_file
+  "#{name}.gemspec"
+end
+
+def gem_file
+  "#{name}-#{version}.gem"
+end
+
+def replace_header(head, header_name)
+  head.sub!(/(\.#{header_name}\s*= ').*'/) { "#{$1}#{send(header_name)}'"}
+end
+
+#############################################################################
+#
+# Standard tasks
+#
+#############################################################################
+
+task :default => :test
+
+if false
+  require 'rake/testtask'
+  Rake::TestTask.new(:test) do |test|
+    test.libs << 'lib' << 'test'
+    test.pattern = 'test/**/*_test.rb'
+    test.verbose = true
+  end
+else
+  task :test do
+    puts "haven't setup tests yet"
+  end
+end
+
+desc "Open an irb session preloaded with this library"
+task :console do
+  sh "irb -rubygems -r ./lib/#{name}.rb"
+end
+
+#############################################################################
+#
+# Custom tasks (add your own tasks here)
+#
+#############################################################################
+
+
+
+#############################################################################
+#
+# Packaging tasks
+#
+#############################################################################
+
+desc "Create tag v#{version} and build and push #{gem_file} to Rubygems"
+task :release => :build do
+  unless `git branch` =~ /^\* master$/
+    puts "You must be on the master branch to release!"
+    exit!
+  end
+  sh "git commit --allow-empty -a -m 'Release #{version}'"
+  sh "git tag v#{version}"
+  sh "git push origin master"
+  sh "git push origin v#{version}"
+  sh "gem push pkg/#{name}-#{version}.gem"
+end
+
+desc "Build #{gem_file} into the pkg directory"
+task :build => :gemspec do
+  sh "mkdir -p pkg"
+  sh "gem build #{gemspec_file}"
+  sh "mv #{gem_file} pkg"
+end
+
+desc "Generate #{gemspec_file}"
+task :gemspec => :validate do
+  # read spec file and split out manifest section
+  spec = File.read(gemspec_file)
+  head, manifest, tail = spec.split("  # = MANIFEST =\n")
+
+  # replace name version and date
+  replace_header(head, :name)
+  replace_header(head, :version)
+  replace_header(head, :date)
+  #comment this out if your rubyforge_project has a different name
+  replace_header(head, :rubyforge_project)
+
+  # determine file list from git ls-files
+  files = `git ls-files`.
+    split("\n").
+    sort.
+    reject { |file| file =~ /^\./ }.
+    reject { |file| file =~ /^(rdoc|pkg)/ }.
+    map { |file| "    #{file}" }.
+    join("\n")
+
+  # piece file back together and write
+  manifest = "  s.files = %w[\n#{files}\n  ]\n"
+  spec = [head, manifest, tail].join("  # = MANIFEST =\n")
+  File.open(gemspec_file, 'w') { |io| io.write(spec) }
+  puts "Updated #{gemspec_file}"
+end
+
+desc "Validate #{gemspec_file}"
+task :validate do
+  libfiles = Dir['lib/*'] - ["lib/#{name}.rb", "lib/#{name}"]
+  unless libfiles.empty?
+    puts "Directory `lib` should only contain a `#{name}.rb` file and `#{name}` dir."
+    exit!
+  end
+  unless Dir['VERSION*'].empty?
+    puts "A `VERSION` file at root level violates Gem best practices."
+    exit!
+  end
+end
+

lib/rack_monitor.rb

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+module RackMonitor
+  VERSION = "0.0.1"
+
+  # Simple middleware to add a quick status URL for tools like Nagios.
+  class RequestStatus
+    REQUEST_METHOD = 'REQUEST_METHOD'.freeze
+    GET            = 'GET'.freeze
+    PATH_INFO      = 'PATH_INFO'.freeze
+    STATUS_PATH    = '/status'
+
+    # Initializes the middleware.
+    #
+    #     # Responds with "OK" on /status
+    #     use RequestStatus, "OK"
+    #
+    # You can change what URL to look for:
+    #
+    #     use RequestStatus, "OK", "/ping"
+    #
+    # You can also check internal systems and return something more informative.
+    #
+    #     use RequestStatus, lambda {
+    #       status = MyApp.status # A Hash of some live counters or something
+    #       [200, {"Content-Type" => "application/json"}, status.to_json]
+    #     }
+    #
+    # app                  - The next Rack app in the pipeline.
+    # callback_or_response - Either a Proc or a Rack response.
+    # status_path          - Optional String path that returns the status.
+    #                        Default: "/status"
+    #
+    # Returns nothing.
+    def initialize(app, callback_or_response, status_path = nil)
+      @app = app
+      @status_path = (status_path || STATUS_PATH).freeze
+      @callback = callback_or_response
+    end
+
+    def call(env)
+      if env[REQUEST_METHOD] == GET
+        if env[PATH_INFO] == @status_path
+          if @callback.respond_to?(:call)
+            return @callback.call
+          else
+            return @callback
+          end
+        end
+      end
+
+      @app.call env
+    end
+  end
+
+  # Simple middleware that adds the current host name and current git SHA to
+  # the response headers.  This can help diagnose problems by letting you
+  # know what code is running from what machine.
+  class RequestHostname
+    # Initializes the middlware.
+    #
+    # app     - The next Rack app in the pipeline.
+    # options - Hash of options.
+    #           :host      - String hostname.
+    #           :revision  - String SHA that describes the version of code
+    #                        this process is running.
+    #
+    # Returns nothing.
+    def initialize(app, options = {})
+      @app = app
+      @host = options[:host] || `hostname -s`.chomp
+      @sha = options[:revision] || '<none>'
+    end
+
+    def call(env)
+      status, headers, body = @app.call(env)
+      headers['X-Node'] = @host
+      headers['X-Revision'] = @sha
+      [status, headers, body]
+    end
+  end
+
+  # Middleware that tracks the amount of time this process spends processing
+  # requests, as opposed to being idle waiting for a connection. Statistics
+  # are dumped to rack.errors every 5 minutes.
+  #
+  # NOTE This middleware is not thread safe. It should only be used when
+  # rack.multiprocess is true and rack.multithread is false.
+  class ProcessUtilization
+    # Initializes the middleware.
+    #
+    # app      - The next Rack app in the pipeline.
+    # domain   - The String domain name the app runs in.
+    # revision - The String SHA that describes the current version of code.
+    # options  - Hash of options.
+    #            :window   - The Integer number of seconds before the horizon
+    #                        resets.
+    #            :stats    - Optional StatsD client.
+    #            :hostname - Optional String hostname.
+    def initialize(app, domain, revision, options = {})
+      @app = app
+      @domain = domain
+      @revision = revision
+      @window = options[:window] || 100
+      @horizon = nil
+      @active_time = nil
+      @requests = nil
+      @total_requests = 0
+      @worker_number = nil
+      @track_gc = GC.respond_to?(:time)
+
+      if @stats = options[:stats]
+        @hostname = options[:hostname] || `hostname -s`.chomp
+      end
+    end
+
+    # the app's domain name - shown in proctitle
+    attr_accessor :domain
+
+    # the currently running git revision as a 7-sha
+    attr_accessor :revision
+
+    # time when we began sampling. this is reset every once in a while so
+    # averages don't skew over time.
+    attr_accessor :horizon
+
+    # total number of requests that have been processed by this worker since
+    # the horizon time.
+    attr_accessor :requests
+
+    # decimal number of seconds the worker has been active within a request
+    # since the horizon time.
+    attr_accessor :active_time
+
+    # total requests processed by this worker process since it started
+    attr_accessor :total_requests
+
+    # the unicorn worker number
+    attr_accessor :worker_number
+
+    # the amount of time since the horizon
+    def horizon_time
+      Time.now - horizon
+    end
+
+    # decimal number of seconds this process has been active since the horizon
+    # time. This is the inverse of the active time.
+    def idle_time
+      horizon_time - active_time
+    end
+
+    # percentage of time this process has been active since the horizon time.
+    def percentage_active
+      (active_time / horizon_time) * 100
+    end
+
+    # percentage of time this process has been idle since the horizon time.
+    def percentage_idle
+      (idle_time / horizon_time) * 100
+    end
+
+    # number of requests processed per second since the horizon
+    def requests_per_second
+      requests / horizon_time
+    end
+
+    # average response time since the horizon in milliseconds
+    def average_response_time
+      (active_time / requests.to_f) * 1000
+    end
+
+    # called exactly once before the first request is processed by a worker
+    def first_request
+      reset_horizon
+      record_worker_number
+    end
+
+    # resets the horizon and all dependent variables
+    def reset_horizon
+      @horizon = Time.now
+      @active_time = 0.0
+      @requests = 0
+    end
+
+    # extracts the worker number from the unicorn procline
+    def record_worker_number
+      if $0 =~ /^.* worker\[(\d+)\].*$/
+        @worker_number = $1.to_i
+      else
+        @worker_number = nil
+      end
+    end
+
+    # the generated procline
+    def procline
+      "unicorn %s[%s] worker[%02d]: %5d reqs, %4.1f req/s, %4dms avg, %5.1f%% util" % [
+        domain,
+        revision,
+        worker_number.to_i,
+        total_requests.to_i,
+        requests_per_second.to_f,
+        average_response_time.to_i,
+        percentage_active.to_f
+      ]
+    end
+
+    # called immediately after a request to record statistics, update the
+    # procline, and dump information to the logfile
+    def record_request(status)
+      now = Time.now
+      diff = (now - @start)
+      @active_time += diff
+      @requests += 1
+
+      $0 = procline
+
+      if @stats
+        @stats.timing("unicorn.#{@hostname}.response_time", diff * 1000)
+        if suffix = status_suffix(status)
+          @stats.increment "unicorn.#{Gitio.host}.status_code.#{status_suffix(status)}"
+        end
+        if @track_gc && GC.time > 0
+          @stats.timing "unicorn.#{@hostname}.gc.time", GC.time / 1000
+          @stats.count  "unicorn.#{@hostname}.gc.collections", GC.collections
+        end
+      end
+
+      reset_horizon if now - horizon > @window
+    rescue => boom
+      warn "ProcessUtilization#record_request failed: #{boom}"
+    end
+
+    def status_suffix(status)
+      suffix = case status.to_i
+        when 404 then :missing
+        when 422 then :invalid
+        when 503 then :node_down
+        when 500 then :error
+      end
+    end
+
+    # Body wrapper. Yields to the block when body is closed. This is used to
+    # signal when a response is fully finished processing.
+    class Body
+      def initialize(body, &block)
+        @body = body
+        @block = block
+      end
+
+      def each(&block)
+        @body.each(&block)
+      end
+
+      def close
+        @body.close if @body.respond_to?(:close)
+        @block.call
+        nil
+      end
+    end
+
+    # Rack entry point.
+    def call(env)
+      @start = Time.now
+      GC.clear_stats if @track_gc
+
+      @total_requests += 1
+      first_request if @total_requests == 1
+
+      env['process.request_start'] = @start.to_f
+      env['process.total_requests'] = total_requests
+
+      # newrelic X-Request-Start
+      env.delete('HTTP_X_REQUEST_START')
+
+      status, headers, body = @app.call(env)
+      body = Body.new(body) { record_request(status) }
+      [status, headers, body]
+    end
+  end
+end
+

rack_monitor.gemspec

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+## This is the rakegem gemspec template. Make sure you read and understand
+## all of the comments. Some sections require modification, and others can
+## be deleted if you don't need them. Once you understand the contents of
+## this file, feel free to delete any comments that begin with two hash marks.
+## You can find comprehensive Gem::Specification documentation, at
+## http://docs.rubygems.org/read/chapter/20
+Gem::Specification.new do |s|
+  s.specification_version = 2 if s.respond_to? :specification_version=
+  s.required_rubygems_version = Gem::Requirement.new(">= 0") if s.respond_to? :required_rubygems_version=
+  s.rubygems_version = '1.3.5'
+
+  ## Leave these as is they will be modified for you by the rake gemspec task.
+  ## If your rubyforge_project name is different, then edit it and comment out
+  ## the sub! line in the Rakefile
+  s.name              = 'rack_monitor'
+  s.version           = '0.0.1'
+  s.date              = '2011-12-02'
+  s.rubyforge_project = 'rack_monitor'
+
+  ## Make sure your summary is short. The description may be as long
+  ## as you like.
+  s.summary     = "Tools for monitoring Rack apps in production."
+  s.description = "Tools for monitoring Rack apps in production."
+
+  ## List the primary authors. If there are a bunch of authors, it's probably
+  ## better to set the email to an email list or something. If you don't have
+  ## a custom homepage, consider using your GitHub URL or the like.
+  s.authors  = ["Ryan Tomayko", "Rick Olson"]
+  s.email    = 'technoweenie@gmail.com'
+  s.homepage = 'https://github.com/github/rack_monitor'
+
+  ## This gets added to the $LOAD_PATH so that 'lib/NAME.rb' can be required as
+  ## require 'NAME.rb' or'/lib/NAME/file.rb' can be as require 'NAME/file.rb'
+  s.require_paths = %w[lib]
+
+  ## List your runtime dependencies here. Runtime dependencies are those
+  ## that are needed for an end user to actually USE your code.
+  #s.add_dependency('rack', "~> 1.2.6")
+
+  ## List your development dependencies here. Development dependencies are
+  ## those that are only needed during development
+  s.add_development_dependency('rack-test')
+
+  ## Leave this section as-is. It will be automatically generated from the
+  ## contents of your Git repository via the gemspec task. DO NOT REMOVE
+  ## THE MANIFEST COMMENTS, they are used as delimiters by the task.
+  # = MANIFEST =
+  s.files = %w[
+    LICENSE
+    README.md
+    Rakefile
+    lib/rack_monitor.rb
+    rack_monitor.gemspec
+  ]
+  # = MANIFEST =
+
+  ## Test files will be grabbed from the file list. Make sure the path glob
+  ## matches what you actually use.
+  s.test_files = s.files.select { |path| path =~ /^test\/.*_test\.rb/ }
+end
+