Remove "Thin" webserver (#4670)

* Remove EventMachine from Puma

* preparation for Thin removal
* replace EventMachine with Concurrent::TimerTask
* remove "thread_info_event_machine" metrics

* Remove Thin webserver

* Update metrics_spec.rb test

* explicitly start and stop MetricsWebserver with Prometheus middleware

* Fix Rack response for Puma webserver

* Rack expects an enumerable. An empty string doesn't work (it worked for Thin, though).

* Fix CORS unit test

* Shutdown metrics_webserver after each test

* Simplify specs (remove redundancies)

* Remove "threadpool_size" config parameter

* was only used for Thin/EventMachine

* Simplify spec: Extract duplicate double(:server) setup

Author: jochenehret

Gemfile

@@ -6,7 +6,6 @@ gem 'clockwork', require: false
 gem 'cloudfront-signer'
 gem 'concurrent-ruby'
 gem 'digest-xxhash'
-gem 'eventmachine', '~> 1.2.7'
 gem 'fluent-logger'
 gem 'googleapis-common-protos', '>= 1.8.0'
 gem 'hashdiff'
@@ -37,7 +36,6 @@ gem 'sinatra-contrib'
 gem 'statsd-ruby', '~> 1.5.0'
 gem 'steno'
 gem 'talentbox-delayed_job_sequel', '~> 4.3.0'
-gem 'thin'
 gem 'uri', '~> 1.1'
 gem 'vmstat', '~> 2.3'
 

Gemfile.lock

@@ -129,7 +129,6 @@ GEM
       bigdecimal
       rexml
     crass (1.0.6)
-    daemons (1.4.1)
     date (3.5.0)
     debug (1.11.0)
       irb (~> 1.10)
@@ -144,7 +143,6 @@ GEM
     drb (2.2.3)
     erb (5.1.3)
     erubi (1.13.1)
-    eventmachine (1.2.7)
     excon (1.3.0)
       logger
     faraday (0.17.6)
@@ -567,11 +565,6 @@ GEM
       delayed_job (~> 4.1.0)
       sequel (>= 3.38, < 6.0)
       tzinfo
-    thin (2.0.1)
-      daemons (~> 1.0, >= 1.0.9)
-      eventmachine (~> 1.0, >= 1.0.4)
-      logger
-      rack (>= 1, < 4)
     thor (1.4.0)
     tilt (2.6.1)
     timecop (0.9.10)
@@ -624,7 +617,6 @@ DEPENDENCIES
   concurrent-ruby
   debug (~> 1.11)
   digest-xxhash
-  eventmachine (~> 1.2.7)
   fluent-logger
   fog-aliyun
   fog-aws
@@ -690,7 +682,6 @@ DEPENDENCIES
   statsd-ruby (~> 1.5.0)
   steno
   talentbox-delayed_job_sequel (~> 4.3.0)
-  thin
   timecop
   uri (~> 1.1)
   vmstat (~> 2.3)

app/controllers/internal/metrics_controller.rb

@@ -268,5 +268,3 @@ diego:
   pid_limit: 1024
 
 shared_isolation_segment_name: shared
-
-threadpool_size: 20

config/bosh-lite.yml

@@ -394,8 +394,7 @@ locket:
   cert_file: 'spec/fixtures/certs/bbs_client.crt'
   key_file: 'spec/fixtures/certs/bbs_client.key'
 
-threadpool_size: 20
-webserver: thin
+webserver: puma
 default_app_lifecycle: buildpack
 custom_metric_tag_prefix_list: ["metric.tag.cloudfoundry.org"]
 

config/cloud_controller.yml

@@ -1,6 +1,5 @@
 require 'sinatra'
 require 'sequel'
-require 'thin'
 require 'oj'
 require 'delayed_job'
 

lib/cloud_controller.rb

@@ -315,10 +315,9 @@ class ApiSchema < VCAP::Config
           },
 
           request_timeout_in_seconds: Integer,
-          threadpool_size: Integer,
           skip_cert_verify: bool,
 
-          webserver: String, # thin or puma
+          webserver: String, # currently only puma
           optional(:puma) => {
             automatic_worker_count: bool,
             workers: Integer,

lib/cloud_controller/config_schemas/api_schema.rb

@@ -11,15 +11,19 @@ def initialize
       end
 
       def start(config)
-        server = Puma::Server.new(@app)
+        @server = Puma::Server.new(@app)
 
         if config.get(:nginx, :metrics_socket).nil? || config.get(:nginx, :metrics_socket).empty?
-          server.add_tcp_listener('127.0.0.1', 9395)
+          @server.add_tcp_listener('127.0.0.1', 9395)
         else
-          server.add_unix_listener(config.get(:nginx, :metrics_socket))
+          @server.add_unix_listener(config.get(:nginx, :metrics_socket))
         end
 
-        server.run
+        @server.run
+      end
+
+      def stop
+        @server.stop(true)
       end
 
       private

lib/cloud_controller/metrics_webserver.rb

@@ -11,7 +11,6 @@
 require 'cloud_controller/logs/request_logs'
 require 'cloud_controller/telemetry_logger'
 require 'cloud_controller/secrets_fetcher'
-require 'cloud_controller/runners/thin_runner'
 require 'cloud_controller/runners/puma_runner'
 require 'cloud_controller/metrics_webserver'
 require 'prometheus/client/data_stores/direct_file_store'
@@ -33,7 +32,7 @@ def initialize(argv)
 
       # DB connection metrics have a label to determine whether the process accessing the connection is the
       # main or a worker process. We need to set this env variable before `setup_db` otherwise the main process
-      # will show up twice in the metrics as main and worker. Thin metrics will be labeled with main as well.
+      # will show up twice in the metrics as main and worker.
       ENV['PROCESS_TYPE'] = 'main'
 
       setup_cloud_controller
@@ -45,11 +44,7 @@ def initialize(argv)
       builder = RackAppBuilder.new
       app     = builder.build(@config, request_metrics, request_logs)
 
-      @server = if @config.get(:webserver) == 'puma'
-                  VCAP::CloudController::PumaRunner.new(@config, app, logger, periodic_updater, request_logs)
-                else
-                  VCAP::CloudController::ThinRunner.new(@config, app, logger, periodic_updater, request_logs)
-                end
+      @server = VCAP::CloudController::PumaRunner.new(@config, app, logger, periodic_updater, request_logs)
     end
 
     def logger