Complete production-like development-mode profiling environment

development.rb

Rails.application.configure do
  # Settings specified here will take precedence over those in config/application.rb.

  # In the development environment your application's code is reloaded on
  # every request. This slows down response time but is perfect for development
  # since you don't have to restart the web server when you make code changes.
  config.cache_classes = !!ENV["PROFILE"]

  # Do not eager load code on boot.
  config.eager_load = !!ENV["PROFILE"]

  # Show full error reports.
  config.consider_all_requests_local = true

  # Enable/disable caching. By default caching is disabled.
  # Run rails dev:cache to toggle caching.
  if Rails.root.join('tmp', 'caching-dev.txt').exist?
    config.action_controller.perform_caching = true

    config.cache_store = :memory_store
    config.public_file_server.headers = {
      'Cache-Control' => "public, max-age=#{2.days.to_i}"
    }
  else
    config.action_controller.perform_caching = false

    config.cache_store = :null_store
  end

  # Store uploaded files on the local file system (see config/storage.yml for options)
  config.active_storage.service = :local

  # Don't care if the mailer can't send.
  config.action_mailer.raise_delivery_errors = false
  config.action_mailer.delivery_method = :letter_opener_web
  config.action_mailer.default_url_options = { port: 3000 }

  config.action_mailer.perform_caching = false

  # Print deprecation notices to the Rails logger.
  config.active_support.deprecation = :log

  # Raise an error on page load if there are pending migrations.
  config.active_record.migration_error = ENV["PROFILE"] ? false : :page_load

  # Highlight code that triggered database queries in logs.
  config.active_record.verbose_query_logs = !ENV["PROFILE"]

  # Debug mode disables concatenation and preprocessing of assets.
  # This option may cause significant delays in view rendering with a large
  # number of complex assets.
  config.assets.debug = !ENV["PROFILE"]

  # Suppress logger output for asset requests.
  config.assets.quiet = true

  if ENV["PROFILE"]
    config.public_file_server.enabled = true
    config.public_file_server.headers = {
      'Cache-Control' => 'public, s-maxage=31536000, maxage=31536000',
      'Expires' => "#{1.year.from_now.to_formatted_s(:rfc822)}"
    }
    config.assets.compile = false

    # Prod-like logging
    logger           = ActiveSupport::Logger.new(STDOUT)
    logger.formatter = config.log_formatter
    config.logger    = ActiveSupport::TaggedLogging.new(logger)

    config.action_view.cache_template_loading = true
  end

  # Raises error for missing translations
  # config.action_view.raise_on_missing_translations = true

  # Use an evented file watcher to asynchronously detect changes in source code,
  # routes, locales, etc. This feature depends on the listen gem.
  config.file_watcher = ActiveSupport::EventedFileUpdateChecker

  # No precompilation on demand on first request
  config.assets.check_precompiled_asset = false

  require 'bullet' unless ENV["PROFILE"]
end

Taken from codetriage/CodeTriage@a3c9576 and also inspired by https://github.com/rubygems/rubygems.org/blob/b026df86ae9df0e4d4c7dae2f220fe2219d52350/config/environments/development.rb.

rails assets:precompile
PROFILE=true rails s