application.rb

# frozen_string_literal: true

#
# Copyright (C) 2013 - present Instructure, Inc.
#
# This file is part of Canvas.
#
# Canvas is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.

require_relative 'boot'

require "active_record/railtie"
require "action_controller/railtie"
require "action_mailer/railtie"
# require "sprockets/railtie" # Do not enable the Rails Asset Pipeline
require "rails/test_unit/railtie"

Bundler.require(*Rails.groups)

# Zeitwerk does not HAVE to be enabled with rails 6
# Use this environment variable (which may have other file-based ways
# to trigger it later) in order to determine which autoloader we should
# use.  The goal is to move to zeitwerk over time.
# https://guides.rubyonrails.org/autoloading_and_reloading_constants.html
# One way to set this in development would be to use your docker-compose.override.yml
# file to pass an env var to the web container:
#
#  web:
#    <<: *BASE
#    environment:
#      <<: *BASE-ENV
#      VIRTUAL_HOST: .canvas.docker
#      ...
#      CANVAS_ZEITWERK: 1
unless defined?(CANVAS_ZEITWERK)
  CANVAS_ZEITWERK = (ENV['CANVAS_ZEITWERK'] == '1')
end

module CanvasRails
  class Application < Rails::Application

    # this CANVAS_ZEITWERK constant flag is defined above in this file.
    # It should be temporary,
    # and removed once we've fully upgraded to zeitwerk autoloading,
    # at which point the stuff inside this conditional block should remain.
    if CANVAS_ZEITWERK
      config.autoloader = :zeitwerk
      # TODO: when we aren't finding copious errors
      # anymore we can stop logging the autoloading paths.
      # For now, this lets us figure out why constant loading
      # is not behaving as expected quickly and easily:
      Rails.autoloaders.logger = Logger.new("#{Rails.root}/log/autoloading.log")
      #Rails.autoloaders.log!

      # TODO: someday we can use this line, which will NOT
      # add anything on the autoload paths the actual ruby
      # $LOAD_PATH because zeitwerk will take care of anything
      # we autolaod.  This will make ACTUAL require statements
      # that are necessary work faster because they'll have a smaller
      # load path to scan.
      # config.add_autoload_paths_to_load_path = false
    end

    $LOAD_PATH << config.root.to_s
    config.encoding = 'utf-8'
    require 'logging_filter'
    config.filter_parameters.concat LoggingFilter.filtered_parameters
    config.action_dispatch.rescue_responses['AuthenticationMethods::AccessTokenError'] = 401
    config.action_dispatch.rescue_responses['AuthenticationMethods::AccessTokenScopeError'] = 401
    config.action_dispatch.rescue_responses['AuthenticationMethods::LoggedOutError'] = 401
    config.action_dispatch.rescue_responses['CanvasHttp::CircuitBreakerError'] = 502
    config.action_dispatch.default_headers.delete('X-Frame-Options')
    config.action_dispatch.default_headers['Referrer-Policy'] = 'no-referrer-when-downgrade'
    config.action_controller.forgery_protection_origin_check = true
    ActiveSupport.to_time_preserves_timezone = true

    config.app_generators do |c|
      c.test_framework :rspec
      c.integration_tool :rspec
      c.performance_tool :rspec
    end

    # Settings in config/environments/* take precedence over those specified here.
    # Application configuration should go into files in config/initializers
    # -- all .rb files in that directory are automatically loaded.
    # See Rails::Configuration for more options.

    # Make Time.zone default to the specified zone, and make Active Record store time values
    # in the database in UTC, and return them converted to the specified local zone.
    # Run "rake -D time" for a list of tasks for finding time zone names. Comment line to use default local time.
    config.time_zone = 'UTC'

    log_config = File.exist?(Rails.root + 'config/logging.yml') && Rails.application.config_for(:logging).with_indifferent_access
    log_config = { 'logger' => 'rails', 'log_level' => 'debug' }.merge(log_config || {})
    opts = {}
    require 'canvas_logger'

    config.log_level = log_config['log_level']
    log_level = ActiveSupport::Logger.const_get(config.log_level.to_s.upcase)
    opts[:skip_thread_context] = true if log_config['log_context'] == false

    case log_config["logger"]
      when "syslog"
        require 'syslog_wrapper'
        log_config["app_ident"] ||= "canvas-lms"
        log_config["daemon_ident"] ||= "canvas-lms-daemon"
        facilities = 0
        (log_config["facilities"] || []).each do |facility|
          facilities |= Syslog.const_get "LOG_#{facility.to_s.upcase}"
        end
        ident = ENV['RUNNING_AS_DAEMON'] == 'true' ? log_config["daemon_ident"] : log_config["app_ident"]
        opts[:include_pid] = true if log_config["include_pid"] == true
        config.logger = SyslogWrapper.new(ident, facilities, opts)
        config.logger.level = log_level
      else
        log_path = config.paths['log'].first

        if ENV['RUNNING_AS_DAEMON'] == 'true'
          log_path = Rails.root+'log/delayed_job.log'
        end

        config.logger = CanvasLogger.new(log_path, log_level, opts)
    end

    # Activate observers that should always be running
    config.active_record.observers = [:cacher, :stream_item_cache, :live_events_observer ]
    config.active_record.allow_unsafe_raw_sql = :disabled

    config.active_support.encode_big_decimal_as_string = false

    config.paths['lib'].eager_load!
    config.paths.add('app/middleware', eager_load: true, autoload_once: true)

    # prevent directory->module inference in these directories from wreaking
    # havoc on the app (e.g. stylesheets/base -> ::Base)
    config.eager_load_paths -= %W(#{Rails.root}/app/coffeescripts
                                  #{Rails.root}/app/stylesheets
                                  #{Rails.root}/ui)

    config.middleware.use Rack::Chunked
    config.middleware.use Rack::Deflater, if: -> (*) {
      ::Canvas::DynamicSettings.find(tree: :private)["enable_rack_deflation", failsafe: true]
    }
    config.middleware.use Rack::Brotli, if: -> (*) {
      ::Canvas::DynamicSettings.find(tree: :private)["enable_rack_brotli", failsafe: true]
    }

    config.i18n.load_path << Rails.root.join('config', 'locales', 'locales.yml')
    config.i18n.load_path << Rails.root.join('config', 'locales', 'community.csv')

    config.to_prepare do
      require_dependency 'canvas/plugins/default_plugins'
      ActiveSupport::JSON::Encoding.escape_html_entities_in_json = true
    end

    module PostgreSQLEarlyExtensions
      module ConnectionHandling
        def postgresql_connection(config)
          conn_params = config.symbolize_keys

          hosts = Array(conn_params[:host]).presence || [nil]
          hosts.each_with_index do |host, index|
            begin
              conn_params[:host] = host
              return super(conn_params)
              # we _shouldn't_ be catching a NoDatabaseError, but that's what Rails raises
              # for an error where the database name is in the message (i.e. a hostname lookup failure)
              # CANVAS_RAILS6_0 rails 6.1 switches from PG::Error to ActiveRecord::ConnectionNotEstablished
              # for any other error
            rescue ::PG::Error, ::ActiveRecord::NoDatabaseError, ::ActiveRecord::ConnectionNotEstablished
              raise if index == hosts.length - 1
              # else try next host
            end
          end
        end
      end

      def initialize(connection, logger, connection_parameters, config)
        unless config.key?(:prepared_statements)
          config = config.dup
          config[:prepared_statements] = false
        end
        super(connection, logger, connection_parameters, config)
      end

      def connect
        hosts = Array(@connection_parameters[:host]).presence || [nil]
        hosts.each_with_index do |host, index|
          begin
            connection_parameters = @connection_parameters.dup
            connection_parameters[:host] = host
            @connection = PG::Connection.connect(connection_parameters)

            configure_connection

            raise "Canvas requires PostgreSQL 9.5 or newer" unless postgresql_version >= 90500

            break
          rescue ::PG::Error => error
            if error.message.include?("does not exist")
              raise ActiveRecord::NoDatabaseError.new(error.message)
            elsif index == hosts.length - 1
              raise
            end
            # else try next host
          end
        end
      end
    end

    module TypeMapInitializerExtensions
      def query_conditions_for_initial_load
        known_type_names = @store.keys.map { |n| "'#{n}'" } + @store.keys.map { |n| "'_#{n}'" }
        <<~SQL % [known_type_names.join(", "),]
          WHERE
            t.typname IN (%s)
        SQL
      end
    end

    Autoextend.hook(:"ActiveRecord::Base",
      PostgreSQLEarlyExtensions::ConnectionHandling,
        singleton: true)
    Autoextend.hook(:"ActiveRecord::ConnectionAdapters::PostgreSQLAdapter",
                    PostgreSQLEarlyExtensions,
                    method: :prepend)

    Autoextend.hook(:"ActiveRecord::ConnectionAdapters::PostgreSQL::OID::TypeMapInitializer",
                    TypeMapInitializerExtensions,
                    method: :prepend)
    module PatchThorWarning
      # active_model_serializers should be passing `type: :boolean` here:
      # https://github.com/rails-api/active_model_serializers/blob/v0.9.0.alpha1/lib/active_model/serializer/generators/serializer/scaffold_controller_generator.rb#L10
      # but we don't really care about the warning, it only affects using the rails
      # generator for a resource
      #
      # Easiest way to avoid the warning for now is to patch thor
      def validate_default_type!
        return if switch_name == "--serializer"
        super
      end
    end

    Autoextend.hook(:"Thor::Option", PatchThorWarning, method: :prepend)

    # Extend any base classes, even gem classes
    Dir.glob("#{Rails.root}/lib/ext/**/*.rb").each { |file| require file }

    # tell Rails to use the native XML parser instead of REXML
    ActiveSupport::XmlMini.backend = 'Nokogiri'

    class NotImplemented < StandardError; end

    if defined?(PhusionPassenger)
      PhusionPassenger.on_event(:after_installing_signal_handlers) do
        Canvas::Reloader.trap_signal
      end
    else
      config.to_prepare do
        Canvas::Reloader.trap_signal
      end
    end

    # Ensure that the automatic redis reconnection on fork works
    # This is the default in redis-rb, but for some reason rails overrides it
    # See e.g. https://gitlab.com/gitlab-org/gitlab/-/merge_requests/22704
    ActiveSupport::Cache::RedisCacheStore::DEFAULT_REDIS_OPTIONS[:reconnect_attempts] = 1

    # don't wrap fields with errors with a <div class="fieldWithErrors" />,
    # since that could leak information (e.g. valid vs invalid username on
    # login page)
    config.action_view.field_error_proc = Proc.new { |html_tag, instance| html_tag }

    class ExceptionsApp
      def call(env)
        req = ActionDispatch::Request.new(env)
        res = ApplicationController.make_response!(req)
        ApplicationController.dispatch('rescue_action_dispatch_exception', req, res)
      end
    end

    config.exceptions_app = ExceptionsApp.new

    config.before_initialize do
      config.action_controller.asset_host = Canvas::Cdn.method(:asset_host_for)
    end

    if config.action_dispatch.rack_cache != false
      config.action_dispatch.rack_cache[:ignore_headers] =
        %w[Set-Cookie X-Request-Context-Id X-Canvas-User-Id X-Canvas-Meta]
    end

    def validate_secret_key_base(_)
      # no validation; we don't use Rails' CookieStore session middleware, so we
      # don't care about secret_key_base
    end

    class DummyKeyGenerator
      def self.generate_key(*)
      end
    end

    def key_generator
      DummyKeyGenerator
    end

    initializer "canvas.init_dynamic_settings", before: "canvas.extend_shard" do
      settings = ConfigFile.load("consul")
      if settings.present?
        # this is not just for speed in non-consul installations^
        # We also do things like building javascript assets with the base
        # container that only has as many ruby assets as strictly necessary,
        # and these resources actually aren't even on disk in those cases.
        # do not remove this conditional until the asset build no longer
        # needs the rails app for anything.
        require_dependency 'canvas/dynamic_settings'
        Canvas::DynamicSettingsInitializer.bootstrap!
      end
    end

    initializer "canvas.cache_config", before: "canvas.extend_shard" do
      CanvasCacheInit.apply!
    end

    initializer "canvas.extend_shard", before: "active_record.initialize_database" do
      # have to do this before the default shard loads
      Switchman::Shard.serialize :settings, Hash
      Switchman.cache = -> { MultiCache.cache }
    end

    # Newer rails has this in rails proper
    attr_writer :credentials

    initializer "canvas.init_credentials", before: "active_record.initialize_database" do
      self.credentials = Canvas::Credentials.new(credentials)
    end

    # we don't know what middleware to make SessionsTimeout follow until after
    # we've loaded config/initializers/session_store.rb
    initializer("extend_middleware_stack", after: :load_config_initializers) do |app|
      app.config.middleware.insert_before(config.session_store, LoadAccount)
      app.config.middleware.swap(ActionDispatch::RequestId, RequestContext::Generator)
      app.config.middleware.insert_after(config.session_store, RequestContext::Session)
      app.config.middleware.insert_before(Rack::Head, RequestThrottle)
      app.config.middleware.insert_before(Rack::MethodOverride, PreventNonMultipartParse)
    end

    initializer("set_allowed_request_id_setters", after: :finisher_hook) do |app|
      # apparently there is no initialization hook that comes late enough for
      # routes to already be loaded, so we have to load them explicitly
      app.reload_routes!
      RequestContext::Generator.allow_unsigned_request_context_for(
        app.routes.url_helpers.api_graphql_subgraph_path
      )
    end
  end
end