Enable more frozen string in app/models/**/*.rb

Partially addresses #47424.

101 files changed, 205 insertions, 2 deletions

diff --git a/app/models/concerns/access_requestable.rb b/app/models/concerns/access_requestable.rb
index d502e7e54c6..31ee3a4da73 100644
--- a/app/models/concerns/access_requestable.rb
+++ b/app/models/concerns/access_requestable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == AccessRequestable concern
 #
 # Contains functionality related to objects that can receive request for access.
diff --git a/app/models/concerns/artifact_migratable.rb b/app/models/concerns/artifact_migratable.rb
index ff52ca64459..cbd63ba8876 100644
--- a/app/models/concerns/artifact_migratable.rb
+++ b/app/models/concerns/artifact_migratable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Adapter class to unify the interface between mounted uploaders and the
 # Ci::Artifact model
 # Meant to be prepended so the interface can stay the same
diff --git a/app/models/concerns/atomic_internal_id.rb b/app/models/concerns/atomic_internal_id.rb
index 5e39676b24b..7f6d48d972c 100644
--- a/app/models/concerns/atomic_internal_id.rb
+++ b/app/models/concerns/atomic_internal_id.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Include atomic internal id generation scheme for a model
 #
 # This allows us to atomically generate internal ids that are
diff --git a/app/models/concerns/avatarable.rb b/app/models/concerns/avatarable.rb
index a6d604a580d..c0233661a9b 100644
--- a/app/models/concerns/avatarable.rb
+++ b/app/models/concerns/avatarable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Avatarable
   extend ActiveSupport::Concern
 
@@ -57,7 +59,8 @@ module Avatarable
       only_path = false
     end
 
-    url_base = ""
+    url_base = []
+
     if use_asset_host
       url_base << asset_host unless only_path
     else
@@ -65,7 +68,7 @@ module Avatarable
       url_base << gitlab_config.relative_url_root
     end
 
-    url_base + avatar.local_url + query_params
+    url_base.join + avatar.local_url + query_params
   end
 
   # Path that is persisted in the tracking Upload model. Used to fetch the
diff --git a/app/models/concerns/awardable.rb b/app/models/concerns/awardable.rb
index fce37e7f78e..dd07f389fa5 100644
--- a/app/models/concerns/awardable.rb
+++ b/app/models/concerns/awardable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Awardable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/batch_destroy_dependent_associations.rb b/app/models/concerns/batch_destroy_dependent_associations.rb
index 353ee2e73d0..45fbc88fbba 100644
--- a/app/models/concerns/batch_destroy_dependent_associations.rb
+++ b/app/models/concerns/batch_destroy_dependent_associations.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Provides a way to work around Rails issue where dependent objects are all
 # loaded into memory before destroyed: https://github.com/rails/rails/issues/22510.
 #
diff --git a/app/models/concerns/blob_like.rb b/app/models/concerns/blob_like.rb
index adb81561000..e96fefe81c4 100644
--- a/app/models/concerns/blob_like.rb
+++ b/app/models/concerns/blob_like.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module BlobLike
   extend ActiveSupport::Concern
   include Linguist::BlobHelper
diff --git a/app/models/concerns/blocks_json_serialization.rb b/app/models/concerns/blocks_json_serialization.rb
index 8019e6adc1c..d346da1ba4b 100644
--- a/app/models/concerns/blocks_json_serialization.rb
+++ b/app/models/concerns/blocks_json_serialization.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Overrides `as_json` and `to_json` to raise an exception when called in order
 # to prevent accidentally exposing attributes
 #
diff --git a/app/models/concerns/bulk_member_access_load.rb b/app/models/concerns/bulk_member_access_load.rb
index 984c4f53bf7..c4346d5dd17 100644
--- a/app/models/concerns/bulk_member_access_load.rb
+++ b/app/models/concerns/bulk_member_access_load.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Returns and caches in thread max member access for a resource
 #
 module BulkMemberAccessLoad
diff --git a/app/models/concerns/cache_markdown_field.rb b/app/models/concerns/cache_markdown_field.rb
index b05bf909058..6e2adc76ec6 100644
--- a/app/models/concerns/cache_markdown_field.rb
+++ b/app/models/concerns/cache_markdown_field.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This module takes care of updating cache columns for Markdown-containing
 # fields. Use like this in the body of your class:
 #
diff --git a/app/models/concerns/cacheable_attributes.rb b/app/models/concerns/cacheable_attributes.rb
index 606549b947f..62b78c3611c 100644
--- a/app/models/concerns/cacheable_attributes.rb
+++ b/app/models/concerns/cacheable_attributes.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module CacheableAttributes
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/case_sensitivity.rb b/app/models/concerns/case_sensitivity.rb
index 034e9f40ff0..0ba542b75ab 100644
--- a/app/models/concerns/case_sensitivity.rb
+++ b/app/models/concerns/case_sensitivity.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Concern for querying columns with specific case sensitivity handling.
 module CaseSensitivity
   extend ActiveSupport::Concern
diff --git a/app/models/concerns/chronic_duration_attribute.rb b/app/models/concerns/chronic_duration_attribute.rb
index 593a9b3d71d..edf6ac96730 100644
--- a/app/models/concerns/chronic_duration_attribute.rb
+++ b/app/models/concerns/chronic_duration_attribute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ChronicDurationAttribute
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/created_at_filterable.rb b/app/models/concerns/created_at_filterable.rb
index e8a3e41203d..a1f46478b6f 100644
--- a/app/models/concerns/created_at_filterable.rb
+++ b/app/models/concerns/created_at_filterable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module CreatedAtFilterable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/deployment_platform.rb b/app/models/concerns/deployment_platform.rb
index 52851b3d0b2..91052013592 100644
--- a/app/models/concerns/deployment_platform.rb
+++ b/app/models/concerns/deployment_platform.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DeploymentPlatform
   # EE would override this and utilize environment argument
   # rubocop:disable Gitlab/ModuleWithInstanceVariables
diff --git a/app/models/concerns/diff_file.rb b/app/models/concerns/diff_file.rb
index 72332072012..47ea14163dc 100644
--- a/app/models/concerns/diff_file.rb
+++ b/app/models/concerns/diff_file.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffFile
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/discussion_on_diff.rb b/app/models/concerns/discussion_on_diff.rb
index 8b3c55387b3..c180d7b7c9a 100644
--- a/app/models/concerns/discussion_on_diff.rb
+++ b/app/models/concerns/discussion_on_diff.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Contains functionality shared between `DiffDiscussion` and `LegacyDiffDiscussion`.
 module DiscussionOnDiff
   extend ActiveSupport::Concern
diff --git a/app/models/concerns/each_batch.rb b/app/models/concerns/each_batch.rb
index 6ddbb8da1a9..a9e14cb55eb 100644
--- a/app/models/concerns/each_batch.rb
+++ b/app/models/concerns/each_batch.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module EachBatch
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/editable.rb b/app/models/concerns/editable.rb
index c0a3099f676..2e49e720ac9 100644
--- a/app/models/concerns/editable.rb
+++ b/app/models/concerns/editable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Editable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/enum_with_nil.rb b/app/models/concerns/enum_with_nil.rb
index 6b37903da20..23acfe9a55f 100644
--- a/app/models/concerns/enum_with_nil.rb
+++ b/app/models/concerns/enum_with_nil.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module EnumWithNil
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/expirable.rb b/app/models/concerns/expirable.rb
index b66ba08dc59..1f274487935 100644
--- a/app/models/concerns/expirable.rb
+++ b/app/models/concerns/expirable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Expirable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/fast_destroy_all.rb b/app/models/concerns/fast_destroy_all.rb
index 7ea042c6742..65ed46ea202 100644
--- a/app/models/concerns/fast_destroy_all.rb
+++ b/app/models/concerns/fast_destroy_all.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 ##
 # This module is for replacing `dependent: :destroy` and `before_destroy` hooks.
 #
diff --git a/app/models/concerns/faster_cache_keys.rb b/app/models/concerns/faster_cache_keys.rb
index 5b14723fa2d..312a9aa9305 100644
--- a/app/models/concerns/faster_cache_keys.rb
+++ b/app/models/concerns/faster_cache_keys.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module FasterCacheKeys
   # A faster version of Rails' "cache_key" method.
   #
diff --git a/app/models/concerns/feature_gate.rb b/app/models/concerns/feature_gate.rb
index 5db64fe82c4..3f84de54ad5 100644
--- a/app/models/concerns/feature_gate.rb
+++ b/app/models/concerns/feature_gate.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module FeatureGate
   def flipper_id
     return nil if new_record?
diff --git a/app/models/concerns/ghost_user.rb b/app/models/concerns/ghost_user.rb
index da696127a80..15278c431fb 100644
--- a/app/models/concerns/ghost_user.rb
+++ b/app/models/concerns/ghost_user.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module GhostUser
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/group_descendant.rb b/app/models/concerns/group_descendant.rb
index 5e9a95c3282..05cd4265133 100644
--- a/app/models/concerns/group_descendant.rb
+++ b/app/models/concerns/group_descendant.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module GroupDescendant
   # Returns the hierarchy of a project or group in the from of a hash upto a
   # given top.
diff --git a/app/models/concerns/has_status.rb b/app/models/concerns/has_status.rb
index 72c236a0fc7..b3960cbad1a 100644
--- a/app/models/concerns/has_status.rb
+++ b/app/models/concerns/has_status.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module HasStatus
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/has_variable.rb b/app/models/concerns/has_variable.rb
index c8e20c0ab81..dfbe413a878 100644
--- a/app/models/concerns/has_variable.rb
+++ b/app/models/concerns/has_variable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module HasVariable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/ignorable_column.rb b/app/models/concerns/ignorable_column.rb
index 03793e8bcbb..2b074c1921c 100644
--- a/app/models/concerns/ignorable_column.rb
+++ b/app/models/concerns/ignorable_column.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Module that can be included into a model to make it easier to ignore database
 # columns.
 #
diff --git a/app/models/concerns/iid_routes.rb b/app/models/concerns/iid_routes.rb
index 246748cf52c..b7f99e845ca 100644
--- a/app/models/concerns/iid_routes.rb
+++ b/app/models/concerns/iid_routes.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module IidRoutes
   ##
   # This automagically enforces all related routes to use `iid` instead of `id`
diff --git a/app/models/concerns/importable.rb b/app/models/concerns/importable.rb
index c9331eaf4cc..4d2707b08ab 100644
--- a/app/models/concerns/importable.rb
+++ b/app/models/concerns/importable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Importable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index b93c1145f82..7f1ecc2e5d2 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Issuable concern
 #
 # Contains common functionality shared between Issues and MergeRequests
diff --git a/app/models/concerns/loaded_in_group_list.rb b/app/models/concerns/loaded_in_group_list.rb
index 935e9d10133..a2233eb2997 100644
--- a/app/models/concerns/loaded_in_group_list.rb
+++ b/app/models/concerns/loaded_in_group_list.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module LoadedInGroupList
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/manual_inverse_association.rb b/app/models/concerns/manual_inverse_association.rb
index 0fca8feaf89..d0d781dc15f 100644
--- a/app/models/concerns/manual_inverse_association.rb
+++ b/app/models/concerns/manual_inverse_association.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ManualInverseAssociation
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/mentionable.rb b/app/models/concerns/mentionable.rb
index c013e5a708f..7e7eccb1c27 100644
--- a/app/models/concerns/mentionable.rb
+++ b/app/models/concerns/mentionable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Mentionable concern
 #
 # Contains functionality related to objects that can mention Users, Issues, MergeRequests, Commits or Snippets by
diff --git a/app/models/concerns/mentionable/reference_regexes.rb b/app/models/concerns/mentionable/reference_regexes.rb
index 2d86a70c395..f6fd28bac33 100644
--- a/app/models/concerns/mentionable/reference_regexes.rb
+++ b/app/models/concerns/mentionable/reference_regexes.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Mentionable
   module ReferenceRegexes
     def self.reference_pattern(link_patterns, issue_pattern)
diff --git a/app/models/concerns/milestoneish.rb b/app/models/concerns/milestoneish.rb
index 967fd9c5eea..e44a069b730 100644
--- a/app/models/concerns/milestoneish.rb
+++ b/app/models/concerns/milestoneish.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Milestoneish
   def closed_items_count(user)
     memoize_per_user(user, :closed_items_count) do
diff --git a/app/models/concerns/note_on_diff.rb b/app/models/concerns/note_on_diff.rb
index 510b8868462..aad19329be1 100644
--- a/app/models/concerns/note_on_diff.rb
+++ b/app/models/concerns/note_on_diff.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Contains functionality shared between `DiffNote` and `LegacyDiffNote`.
 module NoteOnDiff
   extend ActiveSupport::Concern
diff --git a/app/models/concerns/noteable.rb b/app/models/concerns/noteable.rb
index 86f28f30032..ce778eae271 100644
--- a/app/models/concerns/noteable.rb
+++ b/app/models/concerns/noteable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Noteable
   # Names of all implementers of `Noteable` that support resolvable notes.
   RESOLVABLE_TYPES = %w(MergeRequest).freeze
diff --git a/app/models/concerns/participable.rb b/app/models/concerns/participable.rb
index 01b1ef9f82c..1f6c42f3b3a 100644
--- a/app/models/concerns/participable.rb
+++ b/app/models/concerns/participable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Participable concern
 #
 # Contains functionality related to objects that can have participants, such as
diff --git a/app/models/concerns/presentable.rb b/app/models/concerns/presentable.rb
index bc4fbd19a02..06c300c2e41 100644
--- a/app/models/concerns/presentable.rb
+++ b/app/models/concerns/presentable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Presentable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/project_features_compatibility.rb b/app/models/concerns/project_features_compatibility.rb
index 1f7d78a2efe..f268a842db4 100644
--- a/app/models/concerns/project_features_compatibility.rb
+++ b/app/models/concerns/project_features_compatibility.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Makes api V4 compatible with old project features permissions methods
 #
 # After migrating issues_enabled merge_requests_enabled builds_enabled snippets_enabled and wiki_enabled
diff --git a/app/models/concerns/prometheus_adapter.rb b/app/models/concerns/prometheus_adapter.rb
index 9c36f633395..a29e80fe0c1 100644
--- a/app/models/concerns/prometheus_adapter.rb
+++ b/app/models/concerns/prometheus_adapter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module PrometheusAdapter
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/protected_branch_access.rb b/app/models/concerns/protected_branch_access.rb
index e62f42e8e70..744f7f48dc8 100644
--- a/app/models/concerns/protected_branch_access.rb
+++ b/app/models/concerns/protected_branch_access.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ProtectedBranchAccess
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/protected_ref.rb b/app/models/concerns/protected_ref.rb
index dbe8d31de37..e62e680af6e 100644
--- a/app/models/concerns/protected_ref.rb
+++ b/app/models/concerns/protected_ref.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ProtectedRef
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/protected_ref_access.rb b/app/models/concerns/protected_ref_access.rb
index 5ff7b41b82b..efa666fb3f2 100644
--- a/app/models/concerns/protected_ref_access.rb
+++ b/app/models/concerns/protected_ref_access.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ProtectedRefAccess
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/protected_tag_access.rb b/app/models/concerns/protected_tag_access.rb
index ee65de24dd8..04bd54d6b1c 100644
--- a/app/models/concerns/protected_tag_access.rb
+++ b/app/models/concerns/protected_tag_access.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ProtectedTagAccess
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/reactive_caching.rb b/app/models/concerns/reactive_caching.rb
index 9155d82d567..b24c597ec3d 100644
--- a/app/models/concerns/reactive_caching.rb
+++ b/app/models/concerns/reactive_caching.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # The ReactiveCaching concern is used to fetch some data in the background and
 # store it in the Rails cache, keeping it up-to-date for as long as it is being
 # requested.  If the data hasn't been requested for +reactive_cache_lifetime+,
diff --git a/app/models/concerns/reactive_service.rb b/app/models/concerns/reactive_service.rb
index 713246039c1..af69da24994 100644
--- a/app/models/concerns/reactive_service.rb
+++ b/app/models/concerns/reactive_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ReactiveService
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/redis_cacheable.rb b/app/models/concerns/redis_cacheable.rb
index 3bdc1330d23..69554f18ea2 100644
--- a/app/models/concerns/redis_cacheable.rb
+++ b/app/models/concerns/redis_cacheable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module RedisCacheable
   extend ActiveSupport::Concern
   include Gitlab::Utils::StrongMemoize
diff --git a/app/models/concerns/referable.rb b/app/models/concerns/referable.rb
index b782e85717e..468eaf68883 100644
--- a/app/models/concerns/referable.rb
+++ b/app/models/concerns/referable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Referable concern
 #
 # Contains functionality related to making a model referable in Markdown, such
diff --git a/app/models/concerns/relative_positioning.rb b/app/models/concerns/relative_positioning.rb
index afacdb8cb12..85229cded5d 100644
--- a/app/models/concerns/relative_positioning.rb
+++ b/app/models/concerns/relative_positioning.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module RelativePositioning
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/resolvable_discussion.rb b/app/models/concerns/resolvable_discussion.rb
index 7c236369793..c0490af2453 100644
--- a/app/models/concerns/resolvable_discussion.rb
+++ b/app/models/concerns/resolvable_discussion.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ResolvableDiscussion
   extend ActiveSupport::Concern
   include ::Gitlab::Utils::StrongMemoize
diff --git a/app/models/concerns/resolvable_note.rb b/app/models/concerns/resolvable_note.rb
index 4a0f8b92b3a..f47e20229f1 100644
--- a/app/models/concerns/resolvable_note.rb
+++ b/app/models/concerns/resolvable_note.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ResolvableNote
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/routable.rb b/app/models/concerns/routable.rb
index cb91f8fbac8..b9ffc64e4a9 100644
--- a/app/models/concerns/routable.rb
+++ b/app/models/concerns/routable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Store object full path in separate table for easy lookup and uniq validation
 # Object must have name and path db fields and respond to parent and parent_changed? methods.
 module Routable
diff --git a/app/models/concerns/select_for_project_authorization.rb b/app/models/concerns/select_for_project_authorization.rb
index 7af0fdbd618..39306179eb8 100644
--- a/app/models/concerns/select_for_project_authorization.rb
+++ b/app/models/concerns/select_for_project_authorization.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module SelectForProjectAuthorization
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/sha_attribute.rb b/app/models/concerns/sha_attribute.rb
index 3796737427a..c322c356db2 100644
--- a/app/models/concerns/sha_attribute.rb
+++ b/app/models/concerns/sha_attribute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ShaAttribute
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/sortable.rb b/app/models/concerns/sortable.rb
index cb76ae971d4..92877e32491 100644
--- a/app/models/concerns/sortable.rb
+++ b/app/models/concerns/sortable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Sortable concern
 #
 # Set default scope for ordering objects
diff --git a/app/models/concerns/spammable.rb b/app/models/concerns/spammable.rb
index 5e4274619c4..c6e3dc385fe 100644
--- a/app/models/concerns/spammable.rb
+++ b/app/models/concerns/spammable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Spammable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/storage/legacy_namespace.rb b/app/models/concerns/storage/legacy_namespace.rb
index f5225cd81ed..3b745657a9e 100644
--- a/app/models/concerns/storage/legacy_namespace.rb
+++ b/app/models/concerns/storage/legacy_namespace.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Storage
   module LegacyNamespace
     extend ActiveSupport::Concern
diff --git a/app/models/concerns/storage/legacy_project_wiki.rb b/app/models/concerns/storage/legacy_project_wiki.rb
index ff82cb0ffa9..a377fa1e5de 100644
--- a/app/models/concerns/storage/legacy_project_wiki.rb
+++ b/app/models/concerns/storage/legacy_project_wiki.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Storage
   module LegacyProjectWiki
     extend ActiveSupport::Concern
diff --git a/app/models/concerns/storage/legacy_repository.rb b/app/models/concerns/storage/legacy_repository.rb
index 593749bf019..eb93d0fc7f1 100644
--- a/app/models/concerns/storage/legacy_repository.rb
+++ b/app/models/concerns/storage/legacy_repository.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Storage
   module LegacyRepository
     extend ActiveSupport::Concern
diff --git a/app/models/concerns/strip_attribute.rb b/app/models/concerns/strip_attribute.rb
index 8806ebe897a..344f677a3f3 100644
--- a/app/models/concerns/strip_attribute.rb
+++ b/app/models/concerns/strip_attribute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Strip Attribute module
 #
 # Contains functionality to clean attributes before validation
diff --git a/app/models/concerns/subscribable.rb b/app/models/concerns/subscribable.rb
index f478c8ede18..1d0a61364b0 100644
--- a/app/models/concerns/subscribable.rb
+++ b/app/models/concerns/subscribable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == Subscribable concern
 #
 # Users can subscribe to these models.
diff --git a/app/models/concerns/taskable.rb b/app/models/concerns/taskable.rb
index ccd6f0e0a7d..603d4d62578 100644
--- a/app/models/concerns/taskable.rb
+++ b/app/models/concerns/taskable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'task_list'
 require 'task_list/filter'
 
diff --git a/app/models/concerns/throttled_touch.rb b/app/models/concerns/throttled_touch.rb
index ad0ff0f20d4..797c46f6cc5 100644
--- a/app/models/concerns/throttled_touch.rb
+++ b/app/models/concerns/throttled_touch.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # ThrottledTouch can be used to throttle the number of updates triggered by
 # calling "touch" on an ActiveRecord model.
 module ThrottledTouch
diff --git a/app/models/concerns/time_trackable.rb b/app/models/concerns/time_trackable.rb
index 0fc321c52bc..f61a0bbc65b 100644
--- a/app/models/concerns/time_trackable.rb
+++ b/app/models/concerns/time_trackable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # == TimeTrackable concern
 #
 # Contains functionality related to objects that support time tracking.
diff --git a/app/models/concerns/token_authenticatable.rb b/app/models/concerns/token_authenticatable.rb
index ec3543f7053..522b65e4205 100644
--- a/app/models/concerns/token_authenticatable.rb
+++ b/app/models/concerns/token_authenticatable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module TokenAuthenticatable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/triggerable_hooks.rb b/app/models/concerns/triggerable_hooks.rb
index ec0ed3b795a..f55ab2fcaf3 100644
--- a/app/models/concerns/triggerable_hooks.rb
+++ b/app/models/concerns/triggerable_hooks.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module TriggerableHooks
   AVAILABLE_TRIGGERS = {
     repository_update_hooks:  :repository_update_events,
diff --git a/app/models/concerns/uniquify.rb b/app/models/concerns/uniquify.rb
index 549a76da20e..382e826ec58 100644
--- a/app/models/concerns/uniquify.rb
+++ b/app/models/concerns/uniquify.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Uniquify
 #
 # Return a version of the given 'base' string that is unique
diff --git a/app/models/concerns/updated_at_filterable.rb b/app/models/concerns/updated_at_filterable.rb
index edb423b7828..1ab5ee9fbb9 100644
--- a/app/models/concerns/updated_at_filterable.rb
+++ b/app/models/concerns/updated_at_filterable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module UpdatedAtFilterable
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/valid_attribute.rb b/app/models/concerns/valid_attribute.rb
index 8c35cea8d58..251db9ce30b 100644
--- a/app/models/concerns/valid_attribute.rb
+++ b/app/models/concerns/valid_attribute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ValidAttribute
   extend ActiveSupport::Concern
 
diff --git a/app/models/concerns/with_uploads.rb b/app/models/concerns/with_uploads.rb
index 4245d083a49..e231af5368d 100644
--- a/app/models/concerns/with_uploads.rb
+++ b/app/models/concerns/with_uploads.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Mounted uploaders are destroyed by carrierwave's after_commit
 # hook. This hook fetches upload location (local vs remote) from
 # Upload model. So it's neccessary to make sure that during that
diff --git a/app/models/conversational_development_index/card.rb b/app/models/conversational_development_index/card.rb
index e8f09dc9161..f9180bdd97b 100644
--- a/app/models/conversational_development_index/card.rb
+++ b/app/models/conversational_development_index/card.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ConversationalDevelopmentIndex
   class Card
     attr_accessor :metric, :title, :description, :feature, :blog, :docs
diff --git a/app/models/conversational_development_index/idea_to_production_step.rb b/app/models/conversational_development_index/idea_to_production_step.rb
index 6e1753c9f30..e78a734693c 100644
--- a/app/models/conversational_development_index/idea_to_production_step.rb
+++ b/app/models/conversational_development_index/idea_to_production_step.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ConversationalDevelopmentIndex
   class IdeaToProductionStep
     attr_accessor :metric, :title, :features
diff --git a/app/models/conversational_development_index/metric.rb b/app/models/conversational_development_index/metric.rb
index 0bee62f954f..c54537572d6 100644
--- a/app/models/conversational_development_index/metric.rb
+++ b/app/models/conversational_development_index/metric.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ConversationalDevelopmentIndex
   class Metric < ActiveRecord::Base
     include Presentable
diff --git a/app/models/diff_viewer/added.rb b/app/models/diff_viewer/added.rb
index 1909e6ef9d8..70d13e3478c 100644
--- a/app/models/diff_viewer/added.rb
+++ b/app/models/diff_viewer/added.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class Added < Base
     include Simple
diff --git a/app/models/diff_viewer/base.rb b/app/models/diff_viewer/base.rb
index 0cbe714288d..1176861a827 100644
--- a/app/models/diff_viewer/base.rb
+++ b/app/models/diff_viewer/base.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class Base
     PARTIAL_PATH_PREFIX = 'projects/diffs/viewers'.freeze
diff --git a/app/models/diff_viewer/client_side.rb b/app/models/diff_viewer/client_side.rb
index cf41d07f8eb..cc049e1ca49 100644
--- a/app/models/diff_viewer/client_side.rb
+++ b/app/models/diff_viewer/client_side.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   module ClientSide
     extend ActiveSupport::Concern
diff --git a/app/models/diff_viewer/deleted.rb b/app/models/diff_viewer/deleted.rb
index 9c129bac694..78671084eeb 100644
--- a/app/models/diff_viewer/deleted.rb
+++ b/app/models/diff_viewer/deleted.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class Deleted < Base
     include Simple
diff --git a/app/models/diff_viewer/image.rb b/app/models/diff_viewer/image.rb
index 759d9a36ebb..c356c2ca50e 100644
--- a/app/models/diff_viewer/image.rb
+++ b/app/models/diff_viewer/image.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class Image < Base
     include Rich
diff --git a/app/models/diff_viewer/mode_changed.rb b/app/models/diff_viewer/mode_changed.rb
index d487d996f8d..bd07d1e21b9 100644
--- a/app/models/diff_viewer/mode_changed.rb
+++ b/app/models/diff_viewer/mode_changed.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class ModeChanged < Base
     include Simple
diff --git a/app/models/diff_viewer/no_preview.rb b/app/models/diff_viewer/no_preview.rb
index 5455fee4490..b0dd5fd151d 100644
--- a/app/models/diff_viewer/no_preview.rb
+++ b/app/models/diff_viewer/no_preview.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class NoPreview < Base
     include Simple
diff --git a/app/models/diff_viewer/not_diffable.rb b/app/models/diff_viewer/not_diffable.rb
index 4f9638626ea..dc86599e722 100644
--- a/app/models/diff_viewer/not_diffable.rb
+++ b/app/models/diff_viewer/not_diffable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class NotDiffable < Base
     include Simple
diff --git a/app/models/diff_viewer/renamed.rb b/app/models/diff_viewer/renamed.rb
index f1fbfd8c6d5..70ab9d4ca2c 100644
--- a/app/models/diff_viewer/renamed.rb
+++ b/app/models/diff_viewer/renamed.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class Renamed < Base
     include Simple
diff --git a/app/models/diff_viewer/rich.rb b/app/models/diff_viewer/rich.rb
index 3b0ca6e4cff..2faa1be6567 100644
--- a/app/models/diff_viewer/rich.rb
+++ b/app/models/diff_viewer/rich.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   module Rich
     extend ActiveSupport::Concern
diff --git a/app/models/diff_viewer/server_side.rb b/app/models/diff_viewer/server_side.rb
index aed1a0791b1..977204e6c97 100644
--- a/app/models/diff_viewer/server_side.rb
+++ b/app/models/diff_viewer/server_side.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   module ServerSide
     extend ActiveSupport::Concern
diff --git a/app/models/diff_viewer/simple.rb b/app/models/diff_viewer/simple.rb
index 65750996ee4..8d28ca5239a 100644
--- a/app/models/diff_viewer/simple.rb
+++ b/app/models/diff_viewer/simple.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   module Simple
     extend ActiveSupport::Concern
diff --git a/app/models/diff_viewer/static.rb b/app/models/diff_viewer/static.rb
index d761328b3f6..1278c22185c 100644
--- a/app/models/diff_viewer/static.rb
+++ b/app/models/diff_viewer/static.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   module Static
     extend ActiveSupport::Concern
diff --git a/app/models/diff_viewer/text.rb b/app/models/diff_viewer/text.rb
index 98f4b2aea2a..d3d5055c402 100644
--- a/app/models/diff_viewer/text.rb
+++ b/app/models/diff_viewer/text.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiffViewer
   class Text < Base
     include Simple
diff --git a/app/models/hooks/project_hook.rb b/app/models/hooks/project_hook.rb
index ec072882cc9..18c387f0d34 100644
--- a/app/models/hooks/project_hook.rb
+++ b/app/models/hooks/project_hook.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectHook < WebHook
   include TriggerableHooks
 
diff --git a/app/models/hooks/service_hook.rb b/app/models/hooks/service_hook.rb
index aef11514945..bda82a116a1 100644
--- a/app/models/hooks/service_hook.rb
+++ b/app/models/hooks/service_hook.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ServiceHook < WebHook
   belongs_to :service
   validates :service, presence: true
diff --git a/app/models/hooks/system_hook.rb b/app/models/hooks/system_hook.rb
index 6bef00f26ea..90b4588a325 100644
--- a/app/models/hooks/system_hook.rb
+++ b/app/models/hooks/system_hook.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class SystemHook < WebHook
   include TriggerableHooks
 
diff --git a/app/models/hooks/web_hook.rb b/app/models/hooks/web_hook.rb
index e353abdda9c..f18aadefa5c 100644
--- a/app/models/hooks/web_hook.rb
+++ b/app/models/hooks/web_hook.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class WebHook < ActiveRecord::Base
   include Sortable
 
diff --git a/app/models/hooks/web_hook_log.rb b/app/models/hooks/web_hook_log.rb
index 59a1f2aed69..2d9f7594e8c 100644
--- a/app/models/hooks/web_hook_log.rb
+++ b/app/models/hooks/web_hook_log.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class WebHookLog < ActiveRecord::Base
   belongs_to :web_hook
 
diff --git a/app/models/issue/metrics.rb b/app/models/issue/metrics.rb
index 012d545c440..0f5ee957ec9 100644
--- a/app/models/issue/metrics.rb
+++ b/app/models/issue/metrics.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Issue::Metrics < ActiveRecord::Base
   belongs_to :issue
 
diff --git a/app/models/members/group_member.rb b/app/models/members/group_member.rb
index 5da739f9618..fc49ee7ac8c 100644
--- a/app/models/members/group_member.rb
+++ b/app/models/members/group_member.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GroupMember < Member
   SOURCE_TYPE = 'Namespace'.freeze
 
diff --git a/app/models/members/project_member.rb b/app/models/members/project_member.rb
index 4f27d0aeaf8..0154fe5aeba 100644
--- a/app/models/members/project_member.rb
+++ b/app/models/members/project_member.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectMember < Member
   SOURCE_TYPE = 'Project'.freeze
 
diff --git a/app/models/merge_request/metrics.rb b/app/models/merge_request/metrics.rb
index 9e660eccd86..65e94a97b0a 100644
--- a/app/models/merge_request/metrics.rb
+++ b/app/models/merge_request/metrics.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MergeRequest::Metrics < ActiveRecord::Base
   belongs_to :merge_request
   belongs_to :pipeline, class_name: 'Ci::Pipeline', foreign_key: :pipeline_id
diff --git a/app/models/network/commit.rb b/app/models/network/commit.rb
index d667948deae..6c5a4c56377 100644
--- a/app/models/network/commit.rb
+++ b/app/models/network/commit.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Network
   class Commit
     include ActionView::Helpers::TagHelper
diff --git a/app/models/network/graph.rb b/app/models/network/graph.rb
index 1e0d1f9edcb..1431dfefc55 100644
--- a/app/models/network/graph.rb
+++ b/app/models/network/graph.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Network
   class Graph
     attr_reader :days, :commits, :map, :notes, :repo