around_action_ordering_demo.rb

#!/usr/bin/env ruby

ENV['RAILS_ENV'] = 'development'

require 'rubygems'
require 'bundler/inline'

gemfile(false) do
  source 'https://rubygems.org'

  gem 'puma'
  gem 'excon'
  gem 'rails'

  group :development, optional: true do
    gem 'ruby-debug-ide'
    gem 'debase'
  end
end

require 'pp'
require 'rails'
require 'action_controller/railtie'

SERVER_PATH = Pathname.new(Dir.mktmpdir('puma'))
at_exit do
  SERVER_PATH.rmtree
rescue Errno::ENOENT
  nil
end
Rails::Application.redefine_singleton_method(:find_root) { |*args| SERVER_PATH }

STDERR.sync = true
class MiniApp < Rails::Application
  config.colorize_logging = true
  config.logger = begin
    logger = ActiveSupport::Logger.new(STDERR)
    logger.formatter = config.log_formatter
    ActiveSupport::TaggedLogging.new(logger)
  end
  config.eager_load = false
  config.cache_classes = true
  config.cache = ActiveSupport::Cache::NullStore.new

  config.api_only = true
  middleware.delete ActionDispatch::HostAuthorization
  middleware.delete Rack::Sendfile
  middleware.delete ActionDispatch::ShowExceptions

  config.log_tags = [
    ->(_) { Time.now.rfc3339 },
    :uuid,
    ->(req) { "#{req.method} #{req.path}" }
  ]
end

Rails.application.initialize!

Rails.application.routes.draw do
  root "main#show"
end

class ApplicationController < ActionController::API; end
class FakeError < StandardError; end

class MainController < ApplicationController
  before_action :raise_error
  prepend_around_action :log

  rescue_from FakeError do |e|
    e.backtrace.slice! 1..nil # Hide backtraces to reduce noise
    render plain: e.full_message, status: :internal_server_error
    raise e
  end

  def show
    render plain: 'success'
  end

  def log
    logger.info 'Yielding from #log `around_action`'
    yield
    logger.info 'Returned from `yield` in #log `around_action`'
  ensure
    logger.info 'Entered `ensure` section in #log `around_action`'
    logger.info '**** IF THIS WERE A REAL APP, REQUEST/RESPONSE LOGGING WOULD HAPPEN HERE ****'
    logger.info 'Wrote session to log #log `around_action`'
  end

  def raise_error
    logger.info 'In #raise_error; about to `raise`'
    raise FakeError, 'All your base are belong to us'
  end
end

SOCKET_PATH = SERVER_PATH / 'server.sock'
require 'puma/server'
@server_config = Puma::Configuration.new do |c, *|
  c.bind "unix://#{SOCKET_PATH.to_s}"
  c.app MiniApp
  c.silence_single_worker_warning
  c.workers 1
  c.threads 1, 1
  c.environment 'development'
end.tap(&:load)

Thread.abort_on_exception = true
@launcher_events = Puma::Events.stdio
@launcher_events.on_booted { make_test_request }

@launcher = Puma::Launcher.new(@server_config, events: @launcher_events)
@launcher_thread = Thread.new(@launcher, &:run).tap(&:run)


def make_test_request
  resp = Excon.get('unix:///', socket: SOCKET_PATH.to_s)
  Rails.logger.info "Response: Status #{resp.status} (#{Rack::Utils::HTTP_STATUS_CODES[resp.status]})"
  header_txt = resp.headers.map { |k,v| "#{k}: #{v}" }.join("\n")
  Rails.logger.info "Response Headers:\n#{header_txt}"
  Rails.logger.info "Response Body: \n#####\n#{resp.body}\n#####"

  @launcher.stop
  resp
end

@launcher_thread.join