Replace Unicorn with Puma

Gemfile

@@ -9,11 +9,11 @@ gem 'redis-rails'
 gem 'faraday'
 gem 'faraday_middleware'
 gem 'octokit'
+gem 'puma'
 gem "pg", '0.21.0'
 gem 'rack-timeout'
 gem 'tilt'
 gem 'tire'
-gem 'unicorn'
 gem 'iso8601'
 
 gem 'json'

Gemfile.lock

@@ -106,7 +106,6 @@ GEM
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
     json (2.1.0)
-    kgio (2.11.2)
     launchy (2.4.3)
       addressable (~> 2.3)
     loofah (2.2.0)
@@ -134,6 +133,7 @@ GEM
       byebug (~> 10.0)
       pry (~> 0.10)
     public_suffix (3.0.2)
+    puma (3.11.3)
     rack (1.6.9)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -168,7 +168,6 @@ GEM
       activesupport (= 4.2.10)
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
-    raindrops (0.19.0)
     rake (12.3.0)
     redcarpet (3.4.0)
     redis (4.0.1)
@@ -251,9 +250,6 @@ GEM
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.5)
-    unicorn (5.4.0)
-      kgio (~> 2.6)
-      raindrops (~> 0.7)
     uniform_notifier (1.11.0)
     vcr (4.0.0)
     webmock (3.3.0)
@@ -289,6 +285,7 @@ DEPENDENCIES
   octokit
   pg (= 0.21.0)
   pry-byebug
+  puma
   rack-timeout
   rails (= 4.2.10)
   rails-perftest
@@ -304,7 +301,6 @@ DEPENDENCIES
   tilt
   tire
   uglifier
-  unicorn
   vcr
   webmock
   yajl-ruby

Procfile

@@ -1 +1 @@
-web: bundle exec unicorn -p $PORT -c ./config/unicorn.rb
+web: bundle exec puma -C config/puma.rb

config/puma.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+# Puma can serve each request in a thread from an internal thread pool.
+# The `threads` method setting takes two numbers: a minimum and maximum.
+# Any libraries that use thread pools should be configured to match
+# the maximum value specified for Puma. Default is set to 5 threads for minimum
+# and maximum; this matches the default thread size of Active Record.
+#
+threads_count = Integer(ENV.fetch('RAILS_MAX_THREADS') { 5 })
+threads threads_count, threads_count
+
+# Specifies the `port` that Puma will listen on to receive requests; default is 5000.
+#
+port        ENV.fetch('PORT') { 5000 }
+
+# Specifies the `environment` that Puma will run in.
+#
+environment ENV.fetch('RAILS_ENV') { 'development' }
+
+# Specifies the number of `workers` to boot in clustered mode.
+# Workers are forked webserver processes. If using threads and workers together
+# the concurrency of the application would be max `threads` * `workers`.
+# Workers do not work on JRuby or Windows (both of which do not support
+# processes).
+#
+workers Integer(ENV.fetch('WEB_CONCURRENCY') { 3 })
+
+# Use the `preload_app!` method when specifying a `workers` number.
+# This directive tells Puma to first boot the application and load code
+# before forking the application. This takes advantage of Copy On Write
+# process behavior so workers use less memory. If you use this option
+# you need to make sure to reconnect any threads in the `on_worker_boot`
+# block.
+#
+preload_app!
+
+# If you are preloading your application and using Active Record, it's
+# recommended that you close any connections to the database before workers
+# are forked to prevent connection leakage.
+#
+before_fork do
+  ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
+end
+
+# The code in the `on_worker_boot` will be called if you are using
+# clustered mode by specifying a number of `workers`. After each worker
+# process is booted, this block will be run. If you are using the `preload_app!`
+# option, you will want to use this block to reconnect to any threads
+# or connections that may have been created at application boot, as Ruby
+# cannot share connections between processes.
+#
+on_worker_boot do
+  ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
+end
+
+# Allow puma to be restarted by `rails restart` command.
+plugin :tmp_restart

config/unicorn.rb

@@ -1,22 +0,0 @@
-worker_processes Integer(ENV["WEB_CONCURRENCY"] || 3)
-timeout 15
-preload_app true
-
-before_fork do |server, worker|
-  Signal.trap 'TERM' do
-    puts 'Unicorn master intercepting TERM and sending myself QUIT instead'
-    Process.kill 'QUIT', Process.pid
-  end
-
-  defined?(ActiveRecord::Base) and
-    ActiveRecord::Base.connection.disconnect!
-end
-
-after_fork do |server, worker|
-  Signal.trap 'TERM' do
-    puts 'Unicorn worker intercepting TERM and doing nothing. Wait for master to send QUIT'
-  end
-
-  defined?(ActiveRecord::Base) and
-    ActiveRecord::Base.establish_connection
-end