dotenv: add config/unicorn/unicorn.rb, Procfile.

Procfile

@@ -0,0 +1,2 @@
+unicorn: bundle exec unicorn -c config/unicorn/unicorn.rb
+jobs: bundle exec script/delayed_job run

config/unicorn/unicorn.rb

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+require "dotenv"
+
+rails_env = ENV['RAILS_ENV'] || ENV['RACK_ENV'] || 'development'
+Dotenv.load(".env.local", ".env.#{rails_env}", ".env")
+
+addr = ENV["UNICORN_LISTEN"] || "127.0.0.1:9000"
+app_path = ENV["UNICORN_ROOT"] || Dir.pwd
+instance = "unicorn-#{addr}"
+
+listen addr
+worker_processes ENV["UNICORN_PROCESSES"].to_i || 1
+timeout ENV["UNICORN_TIMEOUT"].to_i || 90
+
+user = ENV["UNICORN_USER"] || "danbooru"
+group = ENV["UNICORN_GROUP"] || "danbooru"
+
+stderr_path ENV["UNICORN_LOG"] || "log/#{instance}.log"
+stdout_path ENV["UNICORN_LOG"] || "log/#{instance}.log"
+
+working_directory app_path
+pid ENV["UNICORN_PIDFILE"] || "#{app_path}/tmp/pids/#{instance}.pid"
+
+if rails_env == "production"
+  preload_app true
+
+  before_fork do |server, worker|
+    ActiveRecord::Base.connection.disconnect! if defined?(ActiveRecord::Base)
+
+    # Throttle the master from forking too quickly by sleeping.  Due
+    # to the implementation of standard Unix signal handlers, this
+    # helps (but does not completely) prevent identical, repeated signals
+    # from being lost when the receiving process is busy.
+    sleep 1
+  end
+
+  after_fork do |server, worker|
+    ActiveRecord::Base.establish_connection if defined?(ActiveRecord::Base)
+  end
+else
+  preload_app false
+end