Use govuk app config (#970)

Gemfile

@@ -15,6 +15,7 @@ gem "ffi", ">= 1.9.24"
 gem "fog-aws"
 gem "friendly_id"
 gem "govspeak"
+gem "govuk_app_config"
 gem "govuk_elements_form_builder", "0.1.1"
 gem "govuk_elements_rails", "2.2.1"
 gem "govuk_frontend_toolkit", "9.0.1"

Gemfile.lock

@@ -825,6 +825,7 @@ DEPENDENCIES
   fog-aws
   friendly_id
   govspeak
+  govuk_app_config
   govuk_elements_form_builder (= 0.1.1)
   govuk_elements_rails (= 2.2.1)
   govuk_frontend_toolkit (= 9.0.1)

config/puma.rb

@@ -1,63 +1,2 @@
-# 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.
-#
-max_threads_count = ENV.fetch("RAILS_MAX_THREADS", 5)
-min_threads_count = ENV.fetch("RAILS_MIN_THREADS") { max_threads_count }
-threads min_threads_count, max_threads_count
-
-# Specifies the `port` that Puma will listen on to receive requests, default is 3000.
-#
-port        ENV.fetch("PORT", 3000)
-
-# 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 ENV.fetch("WEB_CONCURRENCY", 2)
-
-# 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!
-
-# 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 `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, 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
-
-# Activerecord Connection Pool Metrics
-after_worker_boot do
-  if Rails.env.production?
-    require "prometheus_exporter/instrumentation"
-    require "prometheus_exporter/client"
-    PrometheusExporter::Instrumentation::Puma.start
-    PrometheusExporter::Instrumentation::Process.start(type: "web")
-
-    PrometheusExporter::Instrumentation::ActiveRecord.start(
-      custom_labels: { type: "puma_worker" },
-      config_labels: %i[database host],
-    )
-  end
-end
+require "govuk_app_config/govuk_puma"
+GovukPuma.configure_rails(self)