diff --git a/lib/gitlab/background_migration/.rubocop.yml b/lib/gitlab/background_migration/.rubocop.yml
new file mode 100644
index 00000000000..8242821cedc
--- /dev/null
+++ b/lib/gitlab/background_migration/.rubocop.yml
@@ -0,0 +1,52 @@
+# For background migrations we define a custom set of rules to make it less
+# difficult to review these migrations. To reduce the complexity of these
+# migrations some rules may be stricter than the defaults set in the root
+# .rubocop.yml file.
+---
+inherit_from: ../../../.rubocop.yml
+
+Metrics/AbcSize:
+  Enabled: true
+  Max: 30
+  Details: >
+    Code that involves a lot of branches can be very hard to wrap your head
+    around.
+
+Metrics/PerceivedComplexity:
+  Enabled: true
+
+Metrics/LineLength:
+  Enabled: true
+  Details: >
+    Long lines are very hard to read and make it more difficult to review
+    changes.
+
+Metrics/MethodLength:
+  Enabled: true
+  Max: 30
+  Details: >
+    Long methods can be very hard to review. Consider splitting this method up
+    into separate methods.
+
+Metrics/ClassLength:
+  Enabled: true
+  Details: >
+    Long classes can be very hard to review. Consider splitting this class up
+    into multiple classes.
+
+Metrics/BlockLength:
+  Enabled: true
+  Details: >
+    Long blocks can be hard to read. Consider splitting the code into separate
+    methods.
+
+Style/Documentation:
+  Enabled: true
+  Details: >
+    Adding documentation makes it easier to figure out what a migration is
+    supposed to do.
+
+Style/FrozenStringLiteralComment:
+  Enabled: true
+  Details: >-
+    This removes the need for calling "freeze", reducing noise in the code.
diff --git a/lib/gitlab/background_migration/create_fork_network_memberships_range.rb b/lib/gitlab/background_migration/create_fork_network_memberships_range.rb
index 67a39d28944..03b17b319fa 100644
--- a/lib/gitlab/background_migration/create_fork_network_memberships_range.rb
+++ b/lib/gitlab/background_migration/create_fork_network_memberships_range.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class CreateForkNetworkMembershipsRange
diff --git a/lib/gitlab/background_migration/create_gpg_key_subkeys_from_gpg_keys.rb b/lib/gitlab/background_migration/create_gpg_key_subkeys_from_gpg_keys.rb
index e94719db72e..c2bf42f846d 100644
--- a/lib/gitlab/background_migration/create_gpg_key_subkeys_from_gpg_keys.rb
+++ b/lib/gitlab/background_migration/create_gpg_key_subkeys_from_gpg_keys.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Style/Documentation
+
 class Gitlab::BackgroundMigration::CreateGpgKeySubkeysFromGpgKeys
   class GpgKey < ActiveRecord::Base
     self.table_name = 'gpg_keys'
diff --git a/lib/gitlab/background_migration/delete_conflicting_redirect_routes_range.rb b/lib/gitlab/background_migration/delete_conflicting_redirect_routes_range.rb
index b1411be3016..a1af045a71f 100644
--- a/lib/gitlab/background_migration/delete_conflicting_redirect_routes_range.rb
+++ b/lib/gitlab/background_migration/delete_conflicting_redirect_routes_range.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class DeleteConflictingRedirectRoutesRange
diff --git a/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits.rb b/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits.rb
index 380802258f5..fd5cbf76e47 100644
--- a/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits.rb
+++ b/lib/gitlab/background_migration/deserialize_merge_request_diffs_and_commits.rb
@@ -1,3 +1,9 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/MethodLength
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Metrics/AbcSize
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class DeserializeMergeRequestDiffsAndCommits
diff --git a/lib/gitlab/background_migration/migrate_build_stage_id_reference.rb b/lib/gitlab/background_migration/migrate_build_stage_id_reference.rb
index 91540127ea9..0a8a4313cd5 100644
--- a/lib/gitlab/background_migration/migrate_build_stage_id_reference.rb
+++ b/lib/gitlab/background_migration/migrate_build_stage_id_reference.rb
@@ -1,3 +1,6 @@
+# frozen_string_literal: true
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class MigrateBuildStageIdReference
diff --git a/lib/gitlab/background_migration/migrate_events_to_push_event_payloads.rb b/lib/gitlab/background_migration/migrate_events_to_push_event_payloads.rb
index 432f7c3e706..84ac00f1a5c 100644
--- a/lib/gitlab/background_migration/migrate_events_to_push_event_payloads.rb
+++ b/lib/gitlab/background_migration/migrate_events_to_push_event_payloads.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     # Class that migrates events for the new push event payloads setup. All
diff --git a/lib/gitlab/background_migration/migrate_stage_status.rb b/lib/gitlab/background_migration/migrate_stage_status.rb
index b1ff0900709..0e5c7f092f2 100644
--- a/lib/gitlab/background_migration/migrate_stage_status.rb
+++ b/lib/gitlab/background_migration/migrate_stage_status.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/AbcSize
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class MigrateStageStatus
diff --git a/lib/gitlab/background_migration/migrate_system_uploads_to_new_folder.rb b/lib/gitlab/background_migration/migrate_system_uploads_to_new_folder.rb
index 0881244ed49..7f243073fd0 100644
--- a/lib/gitlab/background_migration/migrate_system_uploads_to_new_folder.rb
+++ b/lib/gitlab/background_migration/migrate_system_uploads_to_new_folder.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class MigrateSystemUploadsToNewFolder
diff --git a/lib/gitlab/background_migration/move_personal_snippet_files.rb b/lib/gitlab/background_migration/move_personal_snippet_files.rb
index 07cec96bcc3..a4ef51fd0e8 100644
--- a/lib/gitlab/background_migration/move_personal_snippet_files.rb
+++ b/lib/gitlab/background_migration/move_personal_snippet_files.rb
@@ -1,3 +1,7 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class MovePersonalSnippetFiles
diff --git a/lib/gitlab/background_migration/normalize_ldap_extern_uids_range.rb b/lib/gitlab/background_migration/normalize_ldap_extern_uids_range.rb
index bc53e6d7f94..85749366bfd 100644
--- a/lib/gitlab/background_migration/normalize_ldap_extern_uids_range.rb
+++ b/lib/gitlab/background_migration/normalize_ldap_extern_uids_range.rb
@@ -1,3 +1,10 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/MethodLength
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Metrics/ClassLength
+# rubocop:disable Metrics/BlockLength
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class NormalizeLdapExternUidsRange
diff --git a/lib/gitlab/background_migration/populate_fork_networks_range.rb b/lib/gitlab/background_migration/populate_fork_networks_range.rb
index 2ef3a207dd3..f8508b5fbdf 100644
--- a/lib/gitlab/background_migration/populate_fork_networks_range.rb
+++ b/lib/gitlab/background_migration/populate_fork_networks_range.rb
@@ -1,3 +1,8 @@
+# frozen_string_literal: true
+# rubocop:disable Metrics/MethodLength
+# rubocop:disable Metrics/LineLength
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class PopulateForkNetworksRange
diff --git a/lib/gitlab/background_migration/populate_merge_requests_latest_merge_request_diff_id.rb b/lib/gitlab/background_migration/populate_merge_requests_latest_merge_request_diff_id.rb
index 7e109e96e73..dcac355e1b0 100644
--- a/lib/gitlab/background_migration/populate_merge_requests_latest_merge_request_diff_id.rb
+++ b/lib/gitlab/background_migration/populate_merge_requests_latest_merge_request_diff_id.rb
@@ -1,3 +1,6 @@
+# frozen_string_literal: true
+# rubocop:disable Style/Documentation
+
 module Gitlab
   module BackgroundMigration
     class PopulateMergeRequestsLatestMergeRequestDiffId