Remove rails 4 support in CI, Gemfiles, bin/ and config/

.gitlab-ci.yml

@@ -77,18 +77,6 @@ stages:
     - mysql:5.7
     - redis:alpine
 
-.rails4: &rails4
-  allow_failure: false
-  except:
-    variables:
-      - $CI_COMMIT_REF_NAME =~ /(^docs[\/-].*|.*-docs$)/
-      - $CI_COMMIT_REF_NAME =~ /(^qa[\/-].*|.*-qa$)/
-      - $CI_COMMIT_REF_NAME =~ /norails4/
-      - $RAILS5_DISABLED
-  variables:
-    BUNDLE_GEMFILE: "Gemfile.rails4"
-    RAILS5: "false"
-
 # Skip all jobs except the ones that begin with 'docs/'.
 # Used for commits including ONLY documentation changes.
 # https://docs.gitlab.com/ce/development/documentation/#testing
@@ -180,18 +168,10 @@ stages:
   <<: *rspec-metadata
   <<: *use-pg
 
-.rspec-metadata-pg-rails4: &rspec-metadata-pg-rails4
-  <<: *rspec-metadata-pg
-  <<: *rails4
-
 .rspec-metadata-mysql: &rspec-metadata-mysql
   <<: *rspec-metadata
   <<: *use-mysql
 
-.rspec-metadata-mysql-rails4: &rspec-metadata-mysql-rails4
-  <<: *rspec-metadata-mysql
-  <<: *rails4
-
 .only-canonical-masters: &only-canonical-masters
   only:
     - master@gitlab-org/gitlab-ce
@@ -432,7 +412,6 @@ setup-test-env:
   script:
     - bundle exec ruby -Ispec -e 'require "spec_helper" ; TestEnv.init'
     - scripts/gitaly-test-build # Do not use 'bundle exec' here
-    - BUNDLE_GEMFILE=Gemfile.rails4 bundle install $BUNDLE_INSTALL_FLAGS
   artifacts:
     expire_in: 7d
     paths:
@@ -513,14 +492,6 @@ rspec-mysql:
   <<: *rspec-metadata-mysql
   parallel: 50
 
-rspec-pg-rails4:
-  <<: *rspec-metadata-pg-rails4
-  parallel: 50
-
-rspec-mysql-rails4:
-  <<: *rspec-metadata-mysql-rails4
-  parallel: 50
-
 static-analysis:
   <<: *dedicated-no-docs-no-db-pull-cache-job
   dependencies:
@@ -565,12 +536,6 @@ downtime_check:
     - /(^docs[\/-].*|.*-docs$)/
     - /(^qa[\/-].*|.*-qa$)/
 
-rails4_gemfile_lock_check:
-  <<: *dedicated-no-docs-no-db-pull-cache-job
-  <<: *except-docs-and-qa
-  script:
-    - scripts/rails4-gemfile-lock-check
-
 ee_compat_check:
   <<: *rake-exec
   dependencies: []

Gemfile

-# --- Special code for migrating to Rails 5.0 ---
-def rails5?
-  !%w[0 false].include?(ENV["RAILS5"])
-end
-
-gem_versions = {}
-gem_versions['activerecord_sane_schema_dumper'] = rails5? ? '1.0'    : '0.2'
-gem_versions['rails']                           = rails5? ? '5.0.7'  : '4.2.11'
-gem_versions['rails-i18n']                      = rails5? ? '~> 5.1' : '~> 4.0.9'
-
-# The 2.0.6 version of rack requires monkeypatch to be present in
-# `config.ru`. This can be removed once a new update for Rack
-# is available that contains https://github.com/rack/rack/pull/1201.
-gem_versions['rack']                            = rails5? ? '2.0.6' : '1.6.11'
-# --- The end of special code for migrating to Rails 5.0 ---
-
 source 'https://rubygems.org'
 
-gem 'rails', gem_versions['rails']
+gem 'rails', '5.0.7'
 gem 'rails-deprecated_sanitizer', '~> 1.0.3'
 
 # Improves copy-on-write performance for MRI
@@ -28,11 +12,7 @@ gem 'responders', '~> 2.0'
 gem 'sprockets', '~> 3.7.0'
 
 # Default values for AR models
-if rails5?
-  gem 'gitlab-default_value_for', '~> 3.1.1', require: 'default_value_for'
-else
-  gem 'default_value_for', '~> 3.0.0'
-end
+gem 'gitlab-default_value_for', '~> 3.1.1', require: 'default_value_for'
 
 # Supported DBs
 gem 'mysql2', '~> 0.4.10', group: :mysql
@@ -159,7 +139,10 @@ gem 'icalendar'
 gem 'diffy', '~> 3.1.0'
 
 # Application server
-gem 'rack', gem_versions['rack']
+# The 2.0.6 version of rack requires monkeypatch to be present in
+# `config.ru`. This can be removed once a new update for Rack
+# is available that contains https://github.com/rack/rack/pull/1201.
+gem 'rack', '2.0.6'
 
 group :unicorn do
   gem 'unicorn', '~> 5.1.0'
@@ -297,7 +280,7 @@ gem 'premailer-rails', '~> 1.9.7'
 
 # I18n
 gem 'ruby_parser', '~> 3.8', require: false
-gem 'rails-i18n', gem_versions['rails-i18n']
+gem 'rails-i18n', '~> 5.1'
 gem 'gettext_i18n_rails', '~> 1.8.0'
 gem 'gettext_i18n_rails_js', '~> 1.3'
 gem 'gettext', '~> 3.2.2', require: false, group: :development
@@ -383,7 +366,7 @@ group :development, :test do
   gem 'license_finder', '~> 5.4', require: false
   gem 'knapsack', '~> 1.17'
 
-  gem 'activerecord_sane_schema_dumper', gem_versions['activerecord_sane_schema_dumper']
+  gem 'activerecord_sane_schema_dumper', '1.0'
 
   gem 'stackprof', '~> 0.2.10', require: false
 
@@ -397,8 +380,7 @@ group :test do
   gem 'email_spec', '~> 2.2.0'
   gem 'json-schema', '~> 2.8.0'
   gem 'webmock', '~> 2.3.2'
-  gem 'rails-controller-testing' if rails5? # Rails5 only gem.
-  gem 'test_after_commit', '~> 1.1' unless rails5? # Remove this gem when migrated to rails 5.0. It's been integrated to rails 5.0.
+  gem 'rails-controller-testing'
   gem 'sham_rack', '~> 1.3.6'
   gem 'concurrent-ruby', '~> 1.1'
   gem 'test-prof', '~> 0.2.5'

Gemfile.rails4

-# BUNDLE_GEMFILE=Gemfile.rails4 bundle install
-
-ENV["RAILS5"] = "false"
-
-gemfile = File.expand_path("../Gemfile", __FILE__)
-
-eval(File.read(gemfile), nil, gemfile)

bin/rails

 #!/usr/bin/env ruby
-
-# Remove this block when upgraded to rails 5.0.
-if %w[0 false].include?(ENV["RAILS5"])
-  begin
-    load File.expand_path('../spring', __FILE__)
-  rescue LoadError => e
-    raise unless e.message.include?('spring')
-  end
-end
-
 APP_PATH = File.expand_path('../config/application', __dir__)
 require_relative '../config/boot'
 require 'rails/commands'

bin/rake

 #!/usr/bin/env ruby
-
-# Remove this block when upgraded to rails 5.0.
-if %w[0 false].include?(ENV["RAILS5"])
-  begin
-    load File.expand_path('../spring', __FILE__)
-  rescue LoadError => e
-    raise unless e.message.include?('spring')
-  end
-end
-
 require_relative '../config/boot'
 require 'rake'
 Rake.application.run

bin/rspec

 #!/usr/bin/env ruby
 
-# Remove these two lines below when upgraded to rails 5.0.
-# Allow run `rspec` command as `RAILS5=1 rspec ...` instead of `BUNDLE_GEMFILE=Gemfile.rails5 rspec ...`
-gemfile = %w[0 false].include?(ENV["RAILS5"]) ? "Gemfile.rails4" : "Gemfile"
-ENV['BUNDLE_GEMFILE'] ||= File.expand_path("../#{gemfile}", __dir__)
-
 begin
   load File.expand_path('../spring', __FILE__)
 rescue LoadError => e

bin/setup

 #!/usr/bin/env ruby
 
-def rails5?
-  !%w[0 false].include?(ENV["RAILS5"])
-end
-
 require "pathname"
 
 # path to your application root.
 APP_ROOT = Pathname.new File.expand_path("../../", __FILE__)
 
-if rails5?
-  def system!(*args)
+def system!(*args)
   system(*args) || abort("\n== Command #{args} failed ==")
-  end
 end
 
 Dir.chdir APP_ROOT do
@@ -20,14 +14,8 @@ Dir.chdir APP_ROOT do
   # Add necessary setup steps to this file:
 
   puts "== Installing dependencies =="
-
-  if rails5?
   system! "gem install bundler --conservative"
   system("bundle check") || system!("bundle install")
-  else
-    system "gem install bundler --conservative"
-    system "bundle check || bundle install"
-  end
 
   # puts "\n== Copying sample files =="
   # unless File.exist?("config/database.yml")
@@ -35,27 +23,11 @@ Dir.chdir APP_ROOT do
   # end
 
   puts "\n== Preparing database =="
-
-  if rails5?
   system! "bin/rails db:setup"
-  else
-    system "bin/rake db:reset"
-  end
 
   puts "\n== Removing old logs and tempfiles =="
-
-  if rails5?
   system! "bin/rails log:clear tmp:clear"
-  else
-    system "rm -f log/*"
-    system "rm -rf tmp/cache"
-  end
 
   puts "\n== Restarting application server =="
-
-  if rails5?
   system! "bin/rails restart"
-  else
-    system "touch tmp/restart.txt"
-  end
 end

changelogs/unreleased/remove-rails4-support.yml

+---
+title: Remove rails 4 support in CI, Gemfiles, bin/ and config/
+merge_request: 23717
+author: Jasper Maes
+type: other

config/application.rb

@@ -8,7 +8,7 @@ module Gitlab
   # This method is used for smooth upgrading from the current Rails 4.x to Rails 5.0.
   # https://gitlab.com/gitlab-org/gitlab-ce/issues/14286
   def self.rails5?
-    !%w[0 false].include?(ENV["RAILS5"])
+    true
   end
 
   class Application < Rails::Application
@@ -26,9 +26,6 @@ module Gitlab
     # setting disabled
     require_dependency Rails.root.join('lib/mysql_zero_date')
 
-    # This can be removed when we drop support for rails 4
-    require_dependency Rails.root.join('lib/rails4_migration_version')
-
     # 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.
@@ -86,7 +83,7 @@ module Gitlab
     # namespaces/users.
     # https://github.com/rails/rails/blob/5-0-stable/actioncable/lib/action_cable.rb#L38
     # Please change this value when configuring ActionCable for real usage.
-    config.action_cable.mount_path = "/-/cable" if rails5?
+    config.action_cable.mount_path = "/-/cable"
 
     # Configure sensitive parameters which will be filtered from the log file.
     #
@@ -213,8 +210,6 @@ module Gitlab
 
     config.cache_store = :redis_store, caching_config_hash
 
-    config.active_record.raise_in_transactional_callbacks = true unless rails5?
-
     config.active_job.queue_adapter = :sidekiq
 
     # This is needed for gitlab-shell

config/boot.rb

-def rails5?
-  !%w[0 false].include?(ENV["RAILS5"])
-end
-
-require 'rubygems' unless rails5?
-
-gemfile = rails5? ? "Gemfile" : "Gemfile.rails4"
-ENV['BUNDLE_GEMFILE'] ||= File.expand_path("../#{gemfile}", __dir__)
+ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)
 
 # Set up gems listed in the Gemfile.
 require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])

config/environment.rb

 # Load the rails application
 
-# Remove this condition when upgraded to rails 5.0.
-if %w[0 false].include?(ENV["RAILS5"])
-  require File.expand_path('application', __dir__)
-else
-  require_relative 'application'
-end
+require_relative 'application'
 
 # Initialize the rails application
 Rails.application.initialize!

config/environments/production.rb

@@ -9,11 +9,7 @@ Rails.application.configure do
   config.action_controller.perform_caching = true
 
   # Disable Rails's static asset server (Apache or nginx will already do this)
-  if Gitlab.rails5?
   config.public_file_server.enabled = false
-  else
-    config.serve_static_files = false
-  end
 
   # Compress JavaScripts and CSS.
   config.assets.js_compressor = :uglifier

config/environments/test.rb

@@ -19,13 +19,8 @@ Rails.application.configure do
   # Configure static asset server for tests with Cache-Control for performance
   config.assets.compile = false if ENV['CI']
 
-  if Gitlab.rails5?
   config.public_file_server.enabled = true
   config.public_file_server.headers = { 'Cache-Control' => 'public, max-age=3600' }
-  else
-    config.serve_static_files = true
-    config.static_cache_control = "public, max-age=3600"
-  end
 
   # Show full error reports and disable caching
   config.consider_all_requests_local       = true

config/initializers/active_record_array_type_casting.rb

-# Remove this initializer when upgraded to Rails 5.0
-unless Gitlab.rails5?
-  module ActiveRecord
-    class PredicateBuilder
-      class ArrayHandler
-        module TypeCasting
-          def call(attribute, value)
-            # This is necessary because by default ActiveRecord does not respect
-            # custom type definitions (like our `ShaAttribute`) when providing an
-            # array in `where`, like in `where(commit_sha: [sha1, sha2, sha3])`.
-            model = attribute.relation&.engine
-            type = model.user_provided_columns[attribute.name] if model
-            value = value.map { |value| type.type_cast_for_database(value) } if type
-
-            super(attribute, value)
-          end
-        end
-
-        prepend TypeCasting
-      end
-    end
-  end
-end

config/initializers/active_record_avoid_type_casting_in_uniqueness_validator.rb

@@ -20,14 +20,13 @@
 #
 # This bug was fixed in Rails 5.1 by https://github.com/rails/rails/pull/24745/commits/aa062318c451512035c10898a1af95943b1a3803
 
-if Gitlab.rails5?
-  if Rails.version.start_with?("5.1")
+if Rails.version.start_with?("5.1")
   raise "Remove this monkey patch: #{__FILE__}"
-  end
+end
 
-  # Copy-paste from https://github.com/kamipo/rails/blob/aa062318c451512035c10898a1af95943b1a3803/activerecord/lib/active_record/validations/uniqueness.rb
-  # including local fixes to make Rubocop happy again.
-  module ActiveRecord
+# Copy-paste from https://github.com/kamipo/rails/blob/aa062318c451512035c10898a1af95943b1a3803/activerecord/lib/active_record/validations/uniqueness.rb
+# including local fixes to make Rubocop happy again.
+module ActiveRecord
   module Validations
     class UniquenessValidator < ActiveModel::EachValidator # :nodoc:
       def validate_each(record, attribute, value)
@@ -92,5 +91,4 @@ if Gitlab.rails5?
       end
     end
   end
-  end
 end

config/initializers/active_record_data_types.rb

@@ -65,7 +65,7 @@ elsif Gitlab::Database.mysql?
     prepend RegisterDateTimeWithTimeZone
 
     # Add the class `DateTimeWithTimeZone` so we can map `timestamp` to it.
-    class MysqlDateTimeWithTimeZone < (Gitlab.rails5? ? ActiveRecord::Type::DateTime : MysqlDateTime)
+    class MysqlDateTimeWithTimeZone < ActiveRecord::Type::DateTime
       def type
         :datetime_with_timezone
       end

config/initializers/active_record_locking.rb

@@ -64,7 +64,6 @@ module ActiveRecord
 
     # This is patched because we want `lock_version` default to `NULL`
     # rather than `0`
-    if Gitlab.rails5?
     class LockingType
       def deserialize(value)
         super
@@ -74,12 +73,5 @@ module ActiveRecord
         super
       end
     end
-    else
-      class LockingType < SimpleDelegator
-        def type_cast_from_database(value)
-          super
-        end
-      end
-    end
   end
 end

config/initializers/application_controller_renderer.rb

-# Remove this `if` condition when upgraded to rails 5.0.
-# The body must be kept.
-if Gitlab.rails5?
-  # Be sure to restart your server when you modify this file.
-
-  # ActiveSupport::Reloader.to_prepare do
-  #   ApplicationController.renderer.defaults.merge!(
-  #     http_host: 'example.org',
-  #     https: false
-  #   )
-  # end
-end

config/initializers/ar5_batching.rb

-# Remove this file when upgraded to rails 5.0.
-unless Gitlab.rails5?
-  module ActiveRecord
-    module Batches
-      # Differences from upstream: enumerator support was removed, and custom
-      # order/limit clauses are ignored without a warning.
-      def in_batches(of: 1000, start: nil, finish: nil, load: false)
-        raise "Must provide a block" unless block_given?
-
-        relation = self.reorder(batch_order).limit(of)
-        relation = relation.where(arel_table[primary_key].gteq(start)) if start
-        relation = relation.where(arel_table[primary_key].lteq(finish)) if finish
-        batch_relation = relation
-
-        loop do
-          if load
-            records = batch_relation.records
-            ids = records.map(&:id)
-            yielded_relation = self.where(primary_key => ids)
-            yielded_relation.load_records(records)
-          else
-            ids = batch_relation.pluck(primary_key)
-            yielded_relation = self.where(primary_key => ids)
-          end
-
-          break if ids.empty?
-
-          primary_key_offset = ids.last
-          raise ArgumentError.new("Primary key not included in the custom select clause") unless primary_key_offset
-
-          yield yielded_relation
-
-          break if ids.length < of
-
-          batch_relation = relation.where(arel_table[primary_key].gt(primary_key_offset))
-        end
-      end
-    end
-  end
-end

config/initializers/ar5_pg_10_support.rb

-# Remove this file when upgraded to rails 5.0.
-if !Gitlab.rails5? && Gitlab::Database.postgresql?
-  require 'active_record/connection_adapters/postgresql_adapter'
-  require 'active_record/connection_adapters/postgresql/schema_statements'
-
-  #
-  # Monkey-patch the refused Rails 4.2 patch at https://github.com/rails/rails/pull/31330
-  #
-  # Updates sequence logic to support PostgreSQL 10.
-  #
-  # rubocop:disable all
-  module ActiveRecord
-    module ConnectionAdapters
-
-      # We need #postgresql_version to be public as in ActiveRecord 5 for seed_fu
-      # to work. In ActiveRecord 4, it is protected.
-      # https://github.com/mbleigh/seed-fu/issues/123
-      class PostgreSQLAdapter
-        public :postgresql_version
-      end
-
-      module PostgreSQL
-        module SchemaStatements
-          # Resets the sequence of a table's primary key to the maximum value.
-          def reset_pk_sequence!(table, pk = nil, sequence = nil) #:nodoc:
-            unless pk and sequence
-              default_pk, default_sequence = pk_and_sequence_for(table)
-
-              pk ||= default_pk
-              sequence ||= default_sequence
-            end
-
-            if @logger && pk && !sequence
-              @logger.warn "#{table} has primary key #{pk} with no default sequence"
-            end
-
-            if pk && sequence
-              quoted_sequence = quote_table_name(sequence)
-              max_pk = select_value("SELECT MAX(#{quote_column_name pk}) FROM #{quote_table_name(table)}")
-              if max_pk.nil?
-                if postgresql_version >= 100000
-                  minvalue = select_value("SELECT seqmin FROM pg_sequence WHERE seqrelid = #{quote(quoted_sequence)}::regclass")
-                else
-                  minvalue = select_value("SELECT min_value FROM #{quoted_sequence}")
-                end
-              end
-
-              select_value <<-end_sql, 'SCHEMA'
-                SELECT setval(#{quote(quoted_sequence)}, #{max_pk ? max_pk : minvalue}, #{max_pk ? true : false})
-              end_sql
-            end
-          end
-        end
-      end
-    end
-  end
-  # rubocop:enable all
-end

config/initializers/mysql_set_length_for_binary_indexes.rb

@@ -2,28 +2,6 @@
 # MySQL adapter apply a length of 20. Otherwise MySQL can't create an index on
 # binary columns.
 
-# This module can be removed once a Rails 5 schema is used.
-# It can't be wrapped in a check that checks Gitlab.rails5? because
-# the old Rails 4 schema layout is still used
-module MysqlSetLengthForBinaryIndex
-  def add_index(table_name, column_names, options = {})
-    options[:length] ||= {}
-    Array(column_names).each do |column_name|
-      column = ActiveRecord::Base.connection.columns(table_name).find { |c| c.name == column_name }
-
-      if column&.type == :binary
-        options[:length][column_name] = 20
-      end
-    end
-
-    super(table_name, column_names, options)
-  end
-end
-
-if defined?(ActiveRecord::ConnectionAdapters::Mysql2Adapter)
-  ActiveRecord::ConnectionAdapters::Mysql2Adapter.send(:prepend, MysqlSetLengthForBinaryIndex)
-end
-
 module MysqlSetLengthForBinaryIndexAndIgnorePostgresOptionsForSchema
   # This method is used in Rails 5 schema loading as t.index
   def index(column_names, options = {})
@@ -34,15 +12,6 @@ module MysqlSetLengthForBinaryIndexAndIgnorePostgresOptionsForSchema
       return
     end
 
-    # when running rails 4 with rails 5 schema, rails 4 doesn't support multiple
-    # indexes on the same set of columns. Mysql doesn't support partial indexes, so if
-    # an index already exists and we add another index, skip it if it's partial:
-    # see https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21492#note_102821326
-    if !Gitlab.rails5? && indexes[column_names] && options[:where]
-      warn "WARNING: index on columns #{column_names} already exists and partial index is not supported, skipping."
-      return
-    end
-
     options[:length] ||= {}
     Array(column_names).each do |column_name|
       column = columns.find { |c| c.name == column_name }
@@ -56,14 +25,6 @@ module MysqlSetLengthForBinaryIndexAndIgnorePostgresOptionsForSchema
   end
 end
 
-def mysql_adapter?
-  defined?(ActiveRecord::ConnectionAdapters::Mysql2Adapter) && ActiveRecord::Base.connection.is_a?(ActiveRecord::ConnectionAdapters::Mysql2Adapter)
-end
-
-if Gitlab.rails5?
-  if defined?(ActiveRecord::ConnectionAdapters::MySQL::TableDefinition)
+if defined?(ActiveRecord::ConnectionAdapters::MySQL::TableDefinition)
   ActiveRecord::ConnectionAdapters::MySQL::TableDefinition.send(:prepend, MysqlSetLengthForBinaryIndexAndIgnorePostgresOptionsForSchema)
-  end
-elsif mysql_adapter? && defined?(ActiveRecord::ConnectionAdapters::TableDefinition)
-  ActiveRecord::ConnectionAdapters::TableDefinition.send(:prepend, MysqlSetLengthForBinaryIndexAndIgnorePostgresOptionsForSchema)
 end

config/initializers/new_framework_defaults.rb

 # Remove this `if` condition when upgraded to rails 5.0.
 # The body must be kept.
-if Gitlab.rails5?
-  # Be sure to restart your server when you modify this file.
-  #
-  # This file contains migration options to ease your Rails 5.0 upgrade.
-  #
-  # Once upgraded flip defaults one by one to migrate to the new default.
-  #
-  # Read the Guide for Upgrading Ruby on Rails for more info on each option.
+# Be sure to restart your server when you modify this file.
+#
+# This file contains migration options to ease your Rails 5.0 upgrade.
+#
+# Once upgraded flip defaults one by one to migrate to the new default.
+#
+# Read the Guide for Upgrading Ruby on Rails for more info on each option.
 
-  Rails.application.config.action_controller.raise_on_unfiltered_parameters = true
+Rails.application.config.action_controller.raise_on_unfiltered_parameters = true
 
-  # Enable per-form CSRF tokens. Previous versions had false.
-  Rails.application.config.action_controller.per_form_csrf_tokens = false
+# Enable per-form CSRF tokens. Previous versions had false.
+Rails.application.config.action_controller.per_form_csrf_tokens = false
 
-  # Enable origin-checking CSRF mitigation. Previous versions had false.
-  Rails.application.config.action_controller.forgery_protection_origin_check = false
+# Enable origin-checking CSRF mitigation. Previous versions had false.
+Rails.application.config.action_controller.forgery_protection_origin_check = false
 
-  # Make Ruby 2.4 preserve the timezone of the receiver when calling `to_time`.
-  # Previous versions had false.
-  ActiveSupport.to_time_preserves_timezone = false
+# Make Ruby 2.4 preserve the timezone of the receiver when calling `to_time`.
+# Previous versions had false.
+ActiveSupport.to_time_preserves_timezone = false
 
-  # Require `belongs_to` associations by default. Previous versions had false.
-  Rails.application.config.active_record.belongs_to_required_by_default = false
+# Require `belongs_to` associations by default. Previous versions had false.
+Rails.application.config.active_record.belongs_to_required_by_default = false
 
-  # Do not halt callback chains when a callback returns false. Previous versions had true.
-  ActiveSupport.halt_callback_chains_on_return_false = true
-end
+# Do not halt callback chains when a callback returns false. Previous versions had true.
+ActiveSupport.halt_callback_chains_on_return_false = true

config/initializers/postgresql_opclasses_support.rb

@@ -41,10 +41,7 @@ module ActiveRecord
     # Abstract representation of an index definition on a table. Instances of
     # this type are typically created and returned by methods in database
     # adapters. e.g. ActiveRecord::ConnectionAdapters::AbstractMysqlAdapter#indexes
-    attrs = [:table, :name, :unique, :columns, :lengths, :orders, :where, :type, :using, :opclasses]
-
-    # In Rails 5 the second last attribute is newly `:comment`
-    attrs.insert(-2, :comment) if Gitlab.rails5?
+    attrs = [:table, :name, :unique, :columns, :lengths, :orders, :where, :type, :using, :comment, :opclasses]
 
     class IndexDefinition < Struct.new(*attrs) #:nodoc:
     end
@@ -112,15 +109,8 @@ module ActiveRecord
 
           result.map do |row|
             index_name = row[0]
-            unique = if Gitlab.rails5?
-                       row[1]
-                     else
-                       row[1] == 't'
-                     end
-            indkey = row[2].split(" ")
-            if Gitlab.rails5?
-              indkey = indkey.map(&:to_i)
-            end
+            unique = row[1]
+            indkey = row[2].split(" ").map(&:to_i)
             inddef = row[3]
             oid = row[4]
 
@@ -144,8 +134,7 @@ module ActiveRecord
                                  [column, opclass] if opclass
                                end.compact]
 
-              index_attrs = [table_name, index_name, unique, column_names, [], orders, where, nil, using, opclasses]
-              index_attrs.insert(-2, nil) if Gitlab.rails5? # include index comment for Rails 5
+              index_attrs = [table_name, index_name, unique, column_names, [], orders, where, nil, using, nil, opclasses]
 
               IndexDefinition.new(*index_attrs)
             end
@@ -205,7 +194,7 @@ module ActiveRecord
         index_parts << "using: #{index.using.inspect}" if index.using
         index_parts << "type: #{index.type.inspect}" if index.type
         index_parts << "opclasses: #{index.opclasses.inspect}" if index.opclasses.present?
-        index_parts << "comment: #{index.comment.inspect}" if Gitlab.rails5? && index.comment
+        index_parts << "comment: #{index.comment.inspect}" if index.comment
         index_parts
       end
 

config/initializers/static_files.rb

 app = Rails.application
 
-if (Gitlab.rails5? && app.config.public_file_server.enabled) || app.config.serve_static_files
+if app.config.public_file_server.enabled
   # The `ActionDispatch::Static` middleware intercepts requests for static files
   # by checking if they exist in the `/public` directory.
   # We're replacing it with our `Gitlab::Middleware::Static` that does the same,
   # except ignoring `/uploads`, letting those go through to the GitLab Rails app.
 
-  if Gitlab.rails5?
   app.config.middleware.swap(
     ActionDispatch::Static,
     Gitlab::Middleware::Static,
     app.paths["public"].first,
     headers: app.config.public_file_server.headers
   )
-  else
-    app.config.middleware.swap(
-      ActionDispatch::Static,
-      Gitlab::Middleware::Static,
-      app.paths["public"].first,
-      app.config.static_cache_control
-    )
-  end
 
   # If webpack-dev-server is configured, proxy webpack's public directory
   # instead of looking for static assets

config/initializers/trusted_proxies.rb

@@ -26,12 +26,10 @@ Rails.application.config.action_dispatch.trusted_proxies = (
 # A monkey patch to make trusted proxies work with Rails 5.0.
 # Inspired by https://github.com/rails/rails/issues/5223#issuecomment-263778719
 # Remove this monkey patch when upstream is fixed.
-if Gitlab.rails5?
-  module TrustedProxyMonkeyPatch
+module TrustedProxyMonkeyPatch
   def ip
     @ip ||= (get_header("action_dispatch.remote_ip") || super).to_s
   end
-  end
-
-  ActionDispatch::Request.send(:include, TrustedProxyMonkeyPatch)
 end
+
+ActionDispatch::Request.send(:include, TrustedProxyMonkeyPatch)

danger/gemfile/Dangerfile

@@ -4,7 +4,7 @@ GEMFILE_LOCK_NOT_UPDATED_MESSAGE = <<~MSG.freeze
 Usually, when %<gemfile>s is updated, you should run
 ```
 bundle install && \
-  BUNDLE_GEMFILE=Gemfile.rails5 bundle install
+  bundle install
 ```
 
 or

lib/rails4_migration_version.rb

-# rubocop:disable Naming/FileName
-# frozen_string_literal: true
-
-# When switching to rails 5, we added migration version to all migration
-# classes. This patch makes it possible to run versioned migrations
-# also with rails 4
-
-unless Gitlab.rails5?
-  module ActiveRecord
-    class Migration
-      def self.[](version)
-        Migration
-      end
-    end
-  end
-end

scripts/rails4-gemfile-lock-check

-#!/usr/bin/env bash
-
-echo -e "=> Checking if Gemfile.rails4.lock is up-to-date...\\n"
-
-cp Gemfile.rails4.lock Gemfile.rails4.lock.orig
-BUNDLE_GEMFILE=Gemfile.rails4 bundle install "$BUNDLE_INSTALL_FLAGS"
-diff -u Gemfile.rails4.lock.orig Gemfile.rails4.lock >/dev/null 2>&1
-
-if [ $? == 1 ]
-then
-  diff -u Gemfile.rails4.lock.orig Gemfile.rails4.lock
-
-  echo -e "\\n✖ ERROR: Gemfile.rails4.lock is not up-to-date!
-         Please run 'BUNDLE_GEMFILE=Gemfile.rails4 bundle install'\\n" >&2
-  exit 1
-fi
-
-echo "✔ Gemfile.rails4.lock is up-to-date"
-exit 0

spec/lib/gitlab/database/migration_helpers_spec.rb

@@ -1338,12 +1338,7 @@ describe Gitlab::Database::MigrationHelpers do
   end
 
   describe '#index_exists_by_name?' do
-    # TODO: remove rails5-only after removing rails4 tests
-    # rails 4 can not handle multiple indexes on the same column set if
-    # index was added by 't.index' - t.index is used by default in schema.rb in
-    # rails 5. Let's run this test only in rails 5 env:
-    # see https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21492#note_113602758
-    it 'returns true if an index exists', :rails5 do
+    it 'returns true if an index exists' do
       expect(model.index_exists_by_name?(:projects, 'index_projects_on_path'))
         .to be_truthy
     end

spec/lib/gitlab/database_spec.rb

@@ -462,8 +462,7 @@ describe Gitlab::Database do
         expect(described_class.db_read_only?).to be_truthy
       end
 
-      # TODO: remove rails5-only tag after removing rails4 tests
-      it 'detects a read only database', :rails5 do
+      it 'detects a read only database' do
         allow(ActiveRecord::Base.connection).to receive(:execute).with('SELECT pg_is_in_recovery()').and_return([{ "pg_is_in_recovery" => true }])
 
         expect(described_class.db_read_only?).to be_truthy
@@ -475,8 +474,7 @@ describe Gitlab::Database do
         expect(described_class.db_read_only?).to be_falsey
       end
 
-      # TODO: remove rails5-only tag after removing rails4 tests
-      it 'detects a read write database', :rails5 do
+      it 'detects a read write database' do
         allow(ActiveRecord::Base.connection).to receive(:execute).with('SELECT pg_is_in_recovery()').and_return([{ "pg_is_in_recovery" => false }])
 
         expect(described_class.db_read_only?).to be_falsey

spec/lib/gitlab/github_import/importer/pull_request_importer_spec.rb

@@ -240,12 +240,7 @@ describe Gitlab::GithubImport::Importer::PullRequestImporter, :clean_gitlab_redi
           .and_return(user.id)
       end
 
-      # TODO: remove rails5-only after removing rails4 tests
-      # rails 4 can not handle multiple indexes on the same column set if
-      # index was added by 't.index' - t.index is used by default in schema.rb in
-      # rails 5. Let's run this test only in rails 5 env:
-      # see https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21492#note_113602758
-      it 'returns the existing merge request', :rails5 do
+      it 'returns the existing merge request' do
         mr1, exists1 = importer.create_merge_request
         mr2, exists2 = importer.create_merge_request
 

spec/spec_helper.rb

@@ -235,10 +235,6 @@ RSpec.configure do |config|
     example.run if Gitlab::Database.mysql?
   end
 
-  config.around(:each, :rails5) do |example|
-    example.run if Gitlab.rails5?
-  end
-
   # This makes sure the `ApplicationController#can?` method is stubbed with the
   # original implementation for all view specs.
   config.before(:each, type: :view) do