Enable frozen string in app/models/*.rbrepo-forks/gitlab-ce-frozen-string-enable-app-models

Partially addresses #47424.

139 files changed, 286 insertions, 7 deletions

diff --git a/app/controllers/admin/services_controller.rb b/app/controllers/admin/services_controller.rb
index e70aa549140..91a36af34f3 100644
--- a/app/controllers/admin/services_controller.rb
+++ b/app/controllers/admin/services_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Admin::ServicesController < Admin::ApplicationController
   include ServiceParams
 
@@ -30,7 +32,7 @@ class Admin::ServicesController < Admin::ApplicationController
 
   def services_templates
     Service.available_services_names.map do |service_name|
-      service_template = service_name.concat("_service").camelize.constantize
+      service_template = "#{service_name}_service".camelize.constantize
       service_template.where(template: true).first_or_create
     end
   end
diff --git a/app/models/ability.rb b/app/models/ability.rb
index bb600eaccba..a853106e5bd 100644
--- a/app/models/ability.rb
+++ b/app/models/ability.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'declarative_policy'
 
 class Ability
diff --git a/app/models/abuse_report.rb b/app/models/abuse_report.rb
index 4cbd90c5817..1b78fd04ebb 100644
--- a/app/models/abuse_report.rb
+++ b/app/models/abuse_report.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AbuseReport < ActiveRecord::Base
   include CacheMarkdownField
 
diff --git a/app/models/active_session.rb b/app/models/active_session.rb
index b4a86dbb331..0d9c6a4a1f0 100644
--- a/app/models/active_session.rb
+++ b/app/models/active_session.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ActiveSession
   include ActiveModel::Model
 
diff --git a/app/models/appearance.rb b/app/models/appearance.rb
index b770aadef0e..bffba3e13fa 100644
--- a/app/models/appearance.rb
+++ b/app/models/appearance.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Appearance < ActiveRecord::Base
   include CacheableAttributes
   include CacheMarkdownField
diff --git a/app/models/application_setting.rb b/app/models/application_setting.rb
index f770b219422..bc31e548a09 100644
--- a/app/models/application_setting.rb
+++ b/app/models/application_setting.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ApplicationSetting < ActiveRecord::Base
   include CacheableAttributes
   include CacheMarkdownField
diff --git a/app/models/audit_event.rb b/app/models/audit_event.rb
index 112a8778b4e..8508c88d406 100644
--- a/app/models/audit_event.rb
+++ b/app/models/audit_event.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AuditEvent < ActiveRecord::Base
   serialize :details, Hash # rubocop:disable Cop/ActiveRecordSerialize
 
diff --git a/app/models/award_emoji.rb b/app/models/award_emoji.rb
index 4d1a15c53aa..99c7866d636 100644
--- a/app/models/award_emoji.rb
+++ b/app/models/award_emoji.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AwardEmoji < ActiveRecord::Base
   DOWNVOTE_NAME = "thumbsdown".freeze
   UPVOTE_NAME   = "thumbsup".freeze
diff --git a/app/models/badge.rb b/app/models/badge.rb
index 265c5d872d4..7e3b6b659e4 100644
--- a/app/models/badge.rb
+++ b/app/models/badge.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Badge < ActiveRecord::Base
   # This structure sets the placeholders that the urls
   # can have. This hash also sets which action to ask when
diff --git a/app/models/blob.rb b/app/models/blob.rb
index 71c974b4c09..acc64ffca67 100644
--- a/app/models/blob.rb
+++ b/app/models/blob.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Blob is a Rails-specific wrapper around Gitlab::Git::Blob objects
 class Blob < SimpleDelegator
   CACHE_TIME = 60 # Cache raw blobs referred to by a (mutable) ref for 1 minute
diff --git a/app/models/board.rb b/app/models/board.rb
index bb6bb753daf..a137863456c 100644
--- a/app/models/board.rb
+++ b/app/models/board.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Board < ActiveRecord::Base
   belongs_to :group
   belongs_to :project
diff --git a/app/models/broadcast_message.rb b/app/models/broadcast_message.rb
index 4aa236555cb..baf8adb318b 100644
--- a/app/models/broadcast_message.rb
+++ b/app/models/broadcast_message.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class BroadcastMessage < ActiveRecord::Base
   include CacheMarkdownField
   include Sortable
diff --git a/app/models/chat_name.rb b/app/models/chat_name.rb
index fbd0f123341..03b0af53046 100644
--- a/app/models/chat_name.rb
+++ b/app/models/chat_name.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ChatName < ActiveRecord::Base
   LAST_USED_AT_INTERVAL = 1.hour
 
diff --git a/app/models/chat_team.rb b/app/models/chat_team.rb
index 25ecf2d5937..4e724f9adf7 100644
--- a/app/models/chat_team.rb
+++ b/app/models/chat_team.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ChatTeam < ActiveRecord::Base
   validates :team_id, presence: true
   validates :namespace, uniqueness: true
diff --git a/app/models/commit.rb b/app/models/commit.rb
index 56d4c86774e..8b9f4490ffa 100644
--- a/app/models/commit.rb
+++ b/app/models/commit.rb
@@ -1,4 +1,6 @@
 # coding: utf-8
+# frozen_string_literal: true
+
 class Commit
   extend ActiveModel::Naming
   extend Gitlab::Cache::RequestCache
@@ -339,21 +341,21 @@ class Commit
   end
 
   def cherry_pick_description(user)
-    message_body = "(cherry picked from commit #{sha})"
+    message_body = ["(cherry picked from commit #{sha})"]
 
     if merged_merge_request?(user)
       commits_in_merge_request = merged_merge_request(user).commits
 
       if commits_in_merge_request.present?
-        message_body << "\n"
+        message_body << ""
 
         commits_in_merge_request.reverse.each do |commit_in_merge|
-          message_body << "\n#{commit_in_merge.short_id} #{commit_in_merge.title}"
+          message_body << "#{commit_in_merge.short_id} #{commit_in_merge.title}"
         end
       end
     end
 
-    message_body
+    message_body.join("\n")
   end
 
   def cherry_pick_message(user)
diff --git a/app/models/commit_range.rb b/app/models/commit_range.rb
index b93c111dabc..094747ee48d 100644
--- a/app/models/commit_range.rb
+++ b/app/models/commit_range.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # CommitRange makes it easier to work with commit ranges
 #
 # Examples:
diff --git a/app/models/commit_status.rb b/app/models/commit_status.rb
index 97516079b66..4163fe31477 100644
--- a/app/models/commit_status.rb
+++ b/app/models/commit_status.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CommitStatus < ActiveRecord::Base
   include HasStatus
   include Importable
diff --git a/app/models/compare.rb b/app/models/compare.rb
index feb4b89c781..b2d46ada831 100644
--- a/app/models/compare.rb
+++ b/app/models/compare.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Compare
   include Gitlab::Utils::StrongMemoize
 
diff --git a/app/models/container_repository.rb b/app/models/container_repository.rb
index d0c94d3b694..41413854d5c 100644
--- a/app/models/container_repository.rb
+++ b/app/models/container_repository.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ContainerRepository < ActiveRecord::Base
   belongs_to :project
 
diff --git a/app/models/cycle_analytics.rb b/app/models/cycle_analytics.rb
index b34d1382d43..d0f5b6970b1 100644
--- a/app/models/cycle_analytics.rb
+++ b/app/models/cycle_analytics.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CycleAnalytics
   STAGES = %i[issue plan code test review staging production].freeze
 
diff --git a/app/models/dashboard_milestone.rb b/app/models/dashboard_milestone.rb
index 86eb4ec76fc..96bc8090b81 100644
--- a/app/models/dashboard_milestone.rb
+++ b/app/models/dashboard_milestone.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class DashboardMilestone < GlobalMilestone
   def issues_finder_params
     { authorized_only: true }
diff --git a/app/models/deploy_key.rb b/app/models/deploy_key.rb
index 89a74b7dcb1..fd5d7726fb6 100644
--- a/app/models/deploy_key.rb
+++ b/app/models/deploy_key.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class DeployKey < Key
   include IgnorableColumn
 
diff --git a/app/models/deploy_keys_project.rb b/app/models/deploy_keys_project.rb
index 6eef12c4373..71fd02fac86 100644
--- a/app/models/deploy_keys_project.rb
+++ b/app/models/deploy_keys_project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class DeployKeysProject < ActiveRecord::Base
   belongs_to :project
   belongs_to :deploy_key, inverse_of: :deploy_keys_projects
diff --git a/app/models/deploy_token.rb b/app/models/deploy_token.rb
index 7ab647abe93..446c4576678 100644
--- a/app/models/deploy_token.rb
+++ b/app/models/deploy_token.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class DeployToken < ActiveRecord::Base
   include Expirable
   include TokenAuthenticatable
diff --git a/app/models/deployment.rb b/app/models/deployment.rb
index 687246b47b2..6962b54441b 100644
--- a/app/models/deployment.rb
+++ b/app/models/deployment.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Deployment < ActiveRecord::Base
   include AtomicInternalId
   include IidRoutes
diff --git a/app/models/diff_discussion.rb b/app/models/diff_discussion.rb
index bd6af622bfb..93e3ebf7896 100644
--- a/app/models/diff_discussion.rb
+++ b/app/models/diff_discussion.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A discussion on merge request or commit diffs consisting of `DiffNote` notes.
 #
 # A discussion of this type can be resolvable.
diff --git a/app/models/diff_note.rb b/app/models/diff_note.rb
index d752d5bcdee..58d949315e0 100644
--- a/app/models/diff_note.rb
+++ b/app/models/diff_note.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A note on merge request or commit diffs
 #
 # A note of this type can be resolvable.
diff --git a/app/models/directly_addressed_user.rb b/app/models/directly_addressed_user.rb
index 0d519c6ac22..06df2d6c012 100644
--- a/app/models/directly_addressed_user.rb
+++ b/app/models/directly_addressed_user.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class DirectlyAddressedUser
   class << self
     def reference_pattern
diff --git a/app/models/discussion.rb b/app/models/discussion.rb
index 35a0ef00856..dbc7b6e67be 100644
--- a/app/models/discussion.rb
+++ b/app/models/discussion.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A non-diff discussion on an issue, merge request, commit, or snippet, consisting of `DiscussionNote` notes.
 #
 # A discussion of this type can be resolvable.
diff --git a/app/models/discussion_note.rb b/app/models/discussion_note.rb
index e660b024083..89d86aaed66 100644
--- a/app/models/discussion_note.rb
+++ b/app/models/discussion_note.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A note in a non-diff discussion on an issue, merge request, commit, or snippet.
 #
 # A note of this type can be resolvable.
diff --git a/app/models/email.rb b/app/models/email.rb
index 15bdedeac33..b6a977dfa22 100644
--- a/app/models/email.rb
+++ b/app/models/email.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Email < ActiveRecord::Base
   include Sortable
   include Gitlab::SQL::Pattern
diff --git a/app/models/environment.rb b/app/models/environment.rb
index 4856d313318..c8d1d378ae0 100644
--- a/app/models/environment.rb
+++ b/app/models/environment.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Environment < ActiveRecord::Base
   # Used to generate random suffixes for the slug
   LETTERS = 'a'..'z'
@@ -173,7 +175,7 @@ class Environment < ActiveRecord::Base
   #   * cannot end with `-`
   def generate_slug
     # Lowercase letters and numbers only
-    slugified = name.to_s.downcase.gsub(/[^a-z0-9]/, '-')
+    slugified = +name.to_s.downcase.gsub(/[^a-z0-9]/, '-')
 
     # Must start with a letter
     slugified = 'env-' + slugified unless LETTERS.cover?(slugified[0])
diff --git a/app/models/epic.rb b/app/models/epic.rb
index 286b855de3f..f027993376c 100644
--- a/app/models/epic.rb
+++ b/app/models/epic.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Placeholder class for model that is implemented in EE
 # It reserves '&' as a reference prefix, but the table does not exists in CE
 class Epic < ActiveRecord::Base
diff --git a/app/models/event.rb b/app/models/event.rb
index ac0b1c7b27c..ba28866e8e6 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Event < ActiveRecord::Base
   include Sortable
   include IgnorableColumn
diff --git a/app/models/event_collection.rb b/app/models/event_collection.rb
index 8b8244314af..a4c69b11781 100644
--- a/app/models/event_collection.rb
+++ b/app/models/event_collection.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A collection of events to display in an event list.
 #
 # An EventCollection is meant to be used for displaying events to a user (e.g.
diff --git a/app/models/external_issue.rb b/app/models/external_issue.rb
index 282fd7edcb7..4f73beaafc5 100644
--- a/app/models/external_issue.rb
+++ b/app/models/external_issue.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ExternalIssue
   include Referable
 
diff --git a/app/models/fork_network.rb b/app/models/fork_network.rb
index 7f1728e8c77..1b9bf93cbbc 100644
--- a/app/models/fork_network.rb
+++ b/app/models/fork_network.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ForkNetwork < ActiveRecord::Base
   belongs_to :root_project, class_name: 'Project'
   has_many :fork_network_members
diff --git a/app/models/fork_network_member.rb b/app/models/fork_network_member.rb
index eb9417dc34f..36c66f21b0b 100644
--- a/app/models/fork_network_member.rb
+++ b/app/models/fork_network_member.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ForkNetworkMember < ActiveRecord::Base
   belongs_to :fork_network
   belongs_to :project
diff --git a/app/models/forked_project_link.rb b/app/models/forked_project_link.rb
index 8d35864eff6..0f7067238cd 100644
--- a/app/models/forked_project_link.rb
+++ b/app/models/forked_project_link.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ForkedProjectLink < ActiveRecord::Base
   belongs_to :forked_to_project, -> { where.not(pending_delete: true) }, class_name: 'Project'
   belongs_to :forked_from_project, -> { where.not(pending_delete: true) }, class_name: 'Project'
diff --git a/app/models/generic_commit_status.rb b/app/models/generic_commit_status.rb
index 5ac8bde44cd..3028bf21301 100644
--- a/app/models/generic_commit_status.rb
+++ b/app/models/generic_commit_status.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GenericCommitStatus < CommitStatus
   before_validation :set_default_values
 
diff --git a/app/models/global_label.rb b/app/models/global_label.rb
index 2a1b7564962..c5b2492bbf6 100644
--- a/app/models/global_label.rb
+++ b/app/models/global_label.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GlobalLabel
   attr_accessor :title, :labels
   alias_attribute :name, :title
diff --git a/app/models/global_milestone.rb b/app/models/global_milestone.rb
index dc2f6817190..2ddad9b6b0b 100644
--- a/app/models/global_milestone.rb
+++ b/app/models/global_milestone.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GlobalMilestone
   include Milestoneish
 
diff --git a/app/models/gpg_key.rb b/app/models/gpg_key.rb
index 44eda741679..077afffd358 100644
--- a/app/models/gpg_key.rb
+++ b/app/models/gpg_key.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GpgKey < ActiveRecord::Base
   KEY_PREFIX = '-----BEGIN PGP PUBLIC KEY BLOCK-----'.freeze
   KEY_SUFFIX = '-----END PGP PUBLIC KEY BLOCK-----'.freeze
diff --git a/app/models/gpg_key_subkey.rb b/app/models/gpg_key_subkey.rb
index b57922aba30..440b588bc78 100644
--- a/app/models/gpg_key_subkey.rb
+++ b/app/models/gpg_key_subkey.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GpgKeySubkey < ActiveRecord::Base
   include ShaAttribute
 
diff --git a/app/models/gpg_signature.rb b/app/models/gpg_signature.rb
index bf88d75246f..0816778deae 100644
--- a/app/models/gpg_signature.rb
+++ b/app/models/gpg_signature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GpgSignature < ActiveRecord::Base
   include ShaAttribute
 
diff --git a/app/models/group.rb b/app/models/group.rb
index ddebaff50b0..cd548fc0061 100644
--- a/app/models/group.rb
+++ b/app/models/group.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'carrierwave/orm/activerecord'
 
 class Group < Namespace
diff --git a/app/models/group_custom_attribute.rb b/app/models/group_custom_attribute.rb
index 8157d602d67..22f14885657 100644
--- a/app/models/group_custom_attribute.rb
+++ b/app/models/group_custom_attribute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GroupCustomAttribute < ActiveRecord::Base
   belongs_to :group
 
diff --git a/app/models/group_label.rb b/app/models/group_label.rb
index 92c83b54861..ff14529c6e6 100644
--- a/app/models/group_label.rb
+++ b/app/models/group_label.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GroupLabel < Label
   belongs_to :group
 
diff --git a/app/models/group_milestone.rb b/app/models/group_milestone.rb
index 98135ee3c8b..d6ab32ea7c8 100644
--- a/app/models/group_milestone.rb
+++ b/app/models/group_milestone.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class GroupMilestone < GlobalMilestone
   attr_accessor :group
 
diff --git a/app/models/guest.rb b/app/models/guest.rb
index df287c277a7..9c8097e1ac8 100644
--- a/app/models/guest.rb
+++ b/app/models/guest.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Guest
   class << self
     def can?(action, subject = :global)
diff --git a/app/models/identity.rb b/app/models/identity.rb
index 3fd0c5e751d..f5a13dbd6f2 100644
--- a/app/models/identity.rb
+++ b/app/models/identity.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Identity < ActiveRecord::Base
   def self.uniqueness_scope
     :provider
diff --git a/app/models/import_export_upload.rb b/app/models/import_export_upload.rb
index 60d53d6c2c8..40795d7c42f 100644
--- a/app/models/import_export_upload.rb
+++ b/app/models/import_export_upload.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ImportExportUpload < ActiveRecord::Base
   include WithUploads
   include ObjectStorage::BackgroundMove
diff --git a/app/models/individual_note_discussion.rb b/app/models/individual_note_discussion.rb
index 6be8ca45739..07ee7470ea2 100644
--- a/app/models/individual_note_discussion.rb
+++ b/app/models/individual_note_discussion.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A discussion to wrap a single `Note` note on the root of an issue, merge request,
 # commit, or snippet, that is not displayed as a discussion.
 #
diff --git a/app/models/instance_configuration.rb b/app/models/instance_configuration.rb
index b30b707e5fe..7d8ce0bbd05 100644
--- a/app/models/instance_configuration.rb
+++ b/app/models/instance_configuration.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'resolv'
 
 class InstanceConfiguration
diff --git a/app/models/internal_id.rb b/app/models/internal_id.rb
index f50f28deffe..6a3714f1f10 100644
--- a/app/models/internal_id.rb
+++ b/app/models/internal_id.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # An InternalId is a strictly monotone sequence of integers
 # generated for a given scope and usage.
 #
diff --git a/app/models/issue.rb b/app/models/issue.rb
index 4715d942c8d..bf3cc63968d 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'carrierwave/orm/activerecord'
 
 class Issue < ActiveRecord::Base
diff --git a/app/models/issue_assignee.rb b/app/models/issue_assignee.rb
index 326b9eb7ad5..400c0256945 100644
--- a/app/models/issue_assignee.rb
+++ b/app/models/issue_assignee.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class IssueAssignee < ActiveRecord::Base
   belongs_to :issue
   belongs_to :assignee, class_name: "User", foreign_key: :user_id
diff --git a/app/models/issue_collection.rb b/app/models/issue_collection.rb
index 49f011c113f..05607fc3a08 100644
--- a/app/models/issue_collection.rb
+++ b/app/models/issue_collection.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # IssueCollection can be used to reduce a list of issues down to a subset.
 #
 # IssueCollection is not meant to be some sort of Enumerable, instead it's meant
diff --git a/app/models/key.rb b/app/models/key.rb
index ae5769c0627..3bb0d2f6f9c 100644
--- a/app/models/key.rb
+++ b/app/models/key.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'digest/md5'
 
 class Key < ActiveRecord::Base
diff --git a/app/models/label.rb b/app/models/label.rb
index 7bbcaa121ca..f5c60177d52 100644
--- a/app/models/label.rb
+++ b/app/models/label.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Label < ActiveRecord::Base
   include CacheMarkdownField
   include Referable
diff --git a/app/models/label_link.rb b/app/models/label_link.rb
index d68e1f54317..779657b25d5 100644
--- a/app/models/label_link.rb
+++ b/app/models/label_link.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LabelLink < ActiveRecord::Base
   include Importable
 
diff --git a/app/models/label_priority.rb b/app/models/label_priority.rb
index 5b85e0b6533..8ed8bb7577f 100644
--- a/app/models/label_priority.rb
+++ b/app/models/label_priority.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LabelPriority < ActiveRecord::Base
   belongs_to :project
   belongs_to :label
diff --git a/app/models/legacy_diff_discussion.rb b/app/models/legacy_diff_discussion.rb
index 80fc6304fd4..7d78c580fa2 100644
--- a/app/models/legacy_diff_discussion.rb
+++ b/app/models/legacy_diff_discussion.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A discussion on merge request or commit diffs consisting of `LegacyDiffNote` notes.
 #
 # All new diff discussions are of the type `DiffDiscussion`, but any diff discussions created
diff --git a/app/models/legacy_diff_note.rb b/app/models/legacy_diff_note.rb
index d90cafd14b4..20f9b18e4ca 100644
--- a/app/models/legacy_diff_note.rb
+++ b/app/models/legacy_diff_note.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A note on merge request or commit diffs, using the legacy implementation.
 #
 # All new diff notes are of the type `DiffNote`, but any diff notes created
diff --git a/app/models/lfs_file_lock.rb b/app/models/lfs_file_lock.rb
index 50bb6ca382d..431d37e12e9 100644
--- a/app/models/lfs_file_lock.rb
+++ b/app/models/lfs_file_lock.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LfsFileLock < ActiveRecord::Base
   belongs_to :project
   belongs_to :user
diff --git a/app/models/lfs_object.rb b/app/models/lfs_object.rb
index 84487031ee5..2a1a4ef48b7 100644
--- a/app/models/lfs_object.rb
+++ b/app/models/lfs_object.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LfsObject < ActiveRecord::Base
   include AfterCommitQueue
   include ObjectStorage::BackgroundMove
diff --git a/app/models/lfs_objects_project.rb b/app/models/lfs_objects_project.rb
index b0625c52b62..353602800d7 100644
--- a/app/models/lfs_objects_project.rb
+++ b/app/models/lfs_objects_project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LfsObjectsProject < ActiveRecord::Base
   belongs_to :project
   belongs_to :lfs_object
diff --git a/app/models/list.rb b/app/models/list.rb
index 4edcfa78835..eabe3ffccbb 100644
--- a/app/models/list.rb
+++ b/app/models/list.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class List < ActiveRecord::Base
   belongs_to :board
   belongs_to :label
diff --git a/app/models/member.rb b/app/models/member.rb
index 00a13a279a9..05c0bc8cb97 100644
--- a/app/models/member.rb
+++ b/app/models/member.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Member < ActiveRecord::Base
   include AfterCommitQueue
   include Sortable
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index b4090fd8baf..cf4ee17d2b0 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MergeRequest < ActiveRecord::Base
   include AtomicInternalId
   include IidRoutes
diff --git a/app/models/merge_request_diff.rb b/app/models/merge_request_diff.rb
index a073bbfad20..b18a8623ce4 100644
--- a/app/models/merge_request_diff.rb
+++ b/app/models/merge_request_diff.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MergeRequestDiff < ActiveRecord::Base
   include Sortable
   include Importable
diff --git a/app/models/merge_request_diff_commit.rb b/app/models/merge_request_diff_commit.rb
index 1c2e57bb01f..4ad3690512d 100644
--- a/app/models/merge_request_diff_commit.rb
+++ b/app/models/merge_request_diff_commit.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MergeRequestDiffCommit < ActiveRecord::Base
   include ShaAttribute
 
diff --git a/app/models/merge_request_diff_file.rb b/app/models/merge_request_diff_file.rb
index cd8ba6b904d..a9f110bec5c 100644
--- a/app/models/merge_request_diff_file.rb
+++ b/app/models/merge_request_diff_file.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MergeRequestDiffFile < ActiveRecord::Base
   include Gitlab::EncodingHelper
   include DiffFile
diff --git a/app/models/merge_requests_closing_issues.rb b/app/models/merge_requests_closing_issues.rb
index 7f7c114803d..242b65bedc0 100644
--- a/app/models/merge_requests_closing_issues.rb
+++ b/app/models/merge_requests_closing_issues.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MergeRequestsClosingIssues < ActiveRecord::Base
   belongs_to :merge_request
   belongs_to :issue
diff --git a/app/models/milestone.rb b/app/models/milestone.rb
index 14cc12b38a5..1f3b3fda1eb 100644
--- a/app/models/milestone.rb
+++ b/app/models/milestone.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Milestone < ActiveRecord::Base
   # Represents a "No Milestone" state used for filtering Issues and Merge
   # Requests that have no milestone assigned.
diff --git a/app/models/namespace.rb b/app/models/namespace.rb
index 7034c633268..75341cab59b 100644
--- a/app/models/namespace.rb
+++ b/app/models/namespace.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Namespace < ActiveRecord::Base
   include CacheMarkdownField
   include Sortable
diff --git a/app/models/note.rb b/app/models/note.rb
index fe3507adcb3..67a507a5685 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A note on the root of an issue, merge request, commit, or snippet.
 #
 # A note of this type is never resolvable.
diff --git a/app/models/note_diff_file.rb b/app/models/note_diff_file.rb
index e688018a6d9..27aef7adc48 100644
--- a/app/models/note_diff_file.rb
+++ b/app/models/note_diff_file.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class NoteDiffFile < ActiveRecord::Base
   include DiffFile
 
diff --git a/app/models/notification_reason.rb b/app/models/notification_reason.rb
index c3965565022..0a13487574f 100644
--- a/app/models/notification_reason.rb
+++ b/app/models/notification_reason.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Holds reasons for a notification to have been sent as well as a priority list to select which reason to use
 # above the rest
 class NotificationReason
diff --git a/app/models/notification_recipient.rb b/app/models/notification_recipient.rb
index 1a03dd9df56..9f16eefe074 100644
--- a/app/models/notification_recipient.rb
+++ b/app/models/notification_recipient.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class NotificationRecipient
   include Gitlab::Utils::StrongMemoize
 
diff --git a/app/models/notification_setting.rb b/app/models/notification_setting.rb
index 1933c46ee44..1df3a51a7fc 100644
--- a/app/models/notification_setting.rb
+++ b/app/models/notification_setting.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class NotificationSetting < ActiveRecord::Base
   include IgnorableColumn
 
diff --git a/app/models/oauth_access_grant.rb b/app/models/oauth_access_grant.rb
index 3a997406565..d5a8a1a25b6 100644
--- a/app/models/oauth_access_grant.rb
+++ b/app/models/oauth_access_grant.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class OauthAccessGrant < Doorkeeper::AccessGrant
   belongs_to :resource_owner, class_name: 'User'
   belongs_to :application, class_name: 'Doorkeeper::Application'
diff --git a/app/models/oauth_access_token.rb b/app/models/oauth_access_token.rb
index e8595b13d6d..0aa920fa828 100644
--- a/app/models/oauth_access_token.rb
+++ b/app/models/oauth_access_token.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class OauthAccessToken < Doorkeeper::AccessToken
   belongs_to :resource_owner, class_name: 'User'
   belongs_to :application, class_name: 'Doorkeeper::Application'
diff --git a/app/models/out_of_context_discussion.rb b/app/models/out_of_context_discussion.rb
index 4227c40b69a..4de717e2c51 100644
--- a/app/models/out_of_context_discussion.rb
+++ b/app/models/out_of_context_discussion.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # When notes on a commit are displayed in the context of a merge request that
 # contains that commit, they are displayed as if they were a discussion.
 #
diff --git a/app/models/pages_domain.rb b/app/models/pages_domain.rb
index bfea64c3759..7739a3894d3 100644
--- a/app/models/pages_domain.rb
+++ b/app/models/pages_domain.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PagesDomain < ActiveRecord::Base
   VERIFICATION_KEY = 'gitlab-pages-verification-code'.freeze
   VERIFICATION_THRESHOLD = 3.days.freeze
diff --git a/app/models/personal_access_token.rb b/app/models/personal_access_token.rb
index 063dc521324..207146479c0 100644
--- a/app/models/personal_access_token.rb
+++ b/app/models/personal_access_token.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PersonalAccessToken < ActiveRecord::Base
   include Expirable
   include TokenAuthenticatable
diff --git a/app/models/personal_snippet.rb b/app/models/personal_snippet.rb
index 355624fd552..1b5be8698b1 100644
--- a/app/models/personal_snippet.rb
+++ b/app/models/personal_snippet.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PersonalSnippet < Snippet
   include WithUploads
 end
diff --git a/app/models/project.rb b/app/models/project.rb
index 32315dfaa01..cb10b06c233 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'carrierwave/orm/activerecord'
 
 class Project < ActiveRecord::Base
diff --git a/app/models/project_authorization.rb b/app/models/project_authorization.rb
index 73302207e6b..746bb4584c9 100644
--- a/app/models/project_authorization.rb
+++ b/app/models/project_authorization.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectAuthorization < ActiveRecord::Base
   belongs_to :user
   belongs_to :project
diff --git a/app/models/project_auto_devops.rb b/app/models/project_auto_devops.rb
index faa831b1949..155400d1a43 100644
--- a/app/models/project_auto_devops.rb
+++ b/app/models/project_auto_devops.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectAutoDevops < ActiveRecord::Base
   belongs_to :project
 
diff --git a/app/models/project_ci_cd_setting.rb b/app/models/project_ci_cd_setting.rb
index 588cced5781..1dad235cc2b 100644
--- a/app/models/project_ci_cd_setting.rb
+++ b/app/models/project_ci_cd_setting.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectCiCdSetting < ActiveRecord::Base
   belongs_to :project, inverse_of: :ci_cd_settings
 
diff --git a/app/models/project_custom_attribute.rb b/app/models/project_custom_attribute.rb
index 3f1a7b86a82..4e767cb3b26 100644
--- a/app/models/project_custom_attribute.rb
+++ b/app/models/project_custom_attribute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectCustomAttribute < ActiveRecord::Base
   belongs_to :project
 
diff --git a/app/models/project_deploy_token.rb b/app/models/project_deploy_token.rb
index ab4482f0c0b..719c492a1ff 100644
--- a/app/models/project_deploy_token.rb
+++ b/app/models/project_deploy_token.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectDeployToken < ActiveRecord::Base
   belongs_to :project
   belongs_to :deploy_token, inverse_of: :project_deploy_tokens
diff --git a/app/models/project_feature.rb b/app/models/project_feature.rb
index 9c768b13f78..d74cb2506ba 100644
--- a/app/models/project_feature.rb
+++ b/app/models/project_feature.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectFeature < ActiveRecord::Base
   # == Project features permissions
   #
diff --git a/app/models/project_group_link.rb b/app/models/project_group_link.rb
index cf8fc41e870..bc3759142ae 100644
--- a/app/models/project_group_link.rb
+++ b/app/models/project_group_link.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectGroupLink < ActiveRecord::Base
   include Expirable
 
diff --git a/app/models/project_import_data.rb b/app/models/project_import_data.rb
index 1d7089ccfc7..2c3080c6d8d 100644
--- a/app/models/project_import_data.rb
+++ b/app/models/project_import_data.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'carrierwave/orm/activerecord'
 
 class ProjectImportData < ActiveRecord::Base
diff --git a/app/models/project_import_state.rb b/app/models/project_import_state.rb
index 1605317ae14..89ed09af96a 100644
--- a/app/models/project_import_state.rb
+++ b/app/models/project_import_state.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectImportState < ActiveRecord::Base
   include AfterCommitQueue
 
diff --git a/app/models/project_label.rb b/app/models/project_label.rb
index 313815e5869..d0b16cc98b4 100644
--- a/app/models/project_label.rb
+++ b/app/models/project_label.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectLabel < Label
   MAX_NUMBER_OF_PRIORITIES = 1
 
diff --git a/app/models/project_snippet.rb b/app/models/project_snippet.rb
index 25b5d777641..b3585c4cf4c 100644
--- a/app/models/project_snippet.rb
+++ b/app/models/project_snippet.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectSnippet < Snippet
   belongs_to :project
   belongs_to :author, class_name: "User"
diff --git a/app/models/project_statistics.rb b/app/models/project_statistics.rb
index 5d4e3c34b39..206d6ac5e88 100644
--- a/app/models/project_statistics.rb
+++ b/app/models/project_statistics.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectStatistics < ActiveRecord::Base
   belongs_to :project
   belongs_to :namespace
diff --git a/app/models/project_team.rb b/app/models/project_team.rb
index c7d0f49d837..33bc6a561f9 100644
--- a/app/models/project_team.rb
+++ b/app/models/project_team.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProjectTeam
   include BulkMemberAccessLoad
 
diff --git a/app/models/protectable_dropdown.rb b/app/models/protectable_dropdown.rb
index c96edc5a259..25e70ab406c 100644
--- a/app/models/protectable_dropdown.rb
+++ b/app/models/protectable_dropdown.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProtectableDropdown
   REF_TYPES = %i[branches tags].freeze
 
diff --git a/app/models/protected_branch.rb b/app/models/protected_branch.rb
index dff99cfca35..6c1073265a1 100644
--- a/app/models/protected_branch.rb
+++ b/app/models/protected_branch.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProtectedBranch < ActiveRecord::Base
   include Gitlab::ShellAdapter
   include ProtectedRef
diff --git a/app/models/protected_ref_matcher.rb b/app/models/protected_ref_matcher.rb
index d970f2b01fc..bfa9180ac93 100644
--- a/app/models/protected_ref_matcher.rb
+++ b/app/models/protected_ref_matcher.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProtectedRefMatcher
   def initialize(protected_ref)
     @protected_ref = protected_ref
diff --git a/app/models/protected_tag.rb b/app/models/protected_tag.rb
index 42a9bcf7723..a36f0d36262 100644
--- a/app/models/protected_tag.rb
+++ b/app/models/protected_tag.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ProtectedTag < ActiveRecord::Base
   include Gitlab::ShellAdapter
   include ProtectedRef
diff --git a/app/models/push_event.rb b/app/models/push_event.rb
index 90c085c888e..9c0267c3140 100644
--- a/app/models/push_event.rb
+++ b/app/models/push_event.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PushEvent < Event
   # This validation exists so we can't accidentally use PushEvent with a
   # different "action" value.
diff --git a/app/models/push_event_payload.rb b/app/models/push_event_payload.rb
index 6cdb1cd4fe9..c7769edf055 100644
--- a/app/models/push_event_payload.rb
+++ b/app/models/push_event_payload.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class PushEventPayload < ActiveRecord::Base
   include ShaAttribute
 
diff --git a/app/models/readme_blob.rb b/app/models/readme_blob.rb
index 1863a08f1de..7b49fa632f6 100644
--- a/app/models/readme_blob.rb
+++ b/app/models/readme_blob.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class ReadmeBlob < SimpleDelegator
   attr_reader :repository
 
diff --git a/app/models/redirect_route.rb b/app/models/redirect_route.rb
index 31de204d824..c6bd4bb6dfa 100644
--- a/app/models/redirect_route.rb
+++ b/app/models/redirect_route.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class RedirectRoute < ActiveRecord::Base
   belongs_to :source, polymorphic: true # rubocop:disable Cop/PolymorphicAssociations
 
diff --git a/app/models/release.rb b/app/models/release.rb
index c936899799e..cba80ad30ca 100644
--- a/app/models/release.rb
+++ b/app/models/release.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Release < ActiveRecord::Base
   include CacheMarkdownField
 
diff --git a/app/models/remote_mirror.rb b/app/models/remote_mirror.rb
index 976b501e297..2cc5e521e3d 100644
--- a/app/models/remote_mirror.rb
+++ b/app/models/remote_mirror.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class RemoteMirror < ActiveRecord::Base
   include AfterCommitQueue
 
diff --git a/app/models/repository.rb b/app/models/repository.rb
index e248f94cbd8..192865dfd61 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'securerandom'
 
 class Repository
diff --git a/app/models/route.rb b/app/models/route.rb
index 2d609920051..4b23dfa5778 100644
--- a/app/models/route.rb
+++ b/app/models/route.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Route < ActiveRecord::Base
   include CaseSensitivity
 
diff --git a/app/models/security_event.rb b/app/models/security_event.rb
index d131c11cb6c..3fe4cc99c9b 100644
--- a/app/models/security_event.rb
+++ b/app/models/security_event.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 class SecurityEvent < AuditEvent
 end
diff --git a/app/models/sent_notification.rb b/app/models/sent_notification.rb
index 3da7c301d28..e65b3df0fb6 100644
--- a/app/models/sent_notification.rb
+++ b/app/models/sent_notification.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class SentNotification < ActiveRecord::Base
   serialize :position, Gitlab::Diff::Position # rubocop:disable Cop/ActiveRecordSerialize
 
diff --git a/app/models/service.rb b/app/models/service.rb
index cbfe0c6eedd..140058771ee 100644
--- a/app/models/service.rb
+++ b/app/models/service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # To add new service you should build a class inherited from Service
 # and implement a set of methods
 class Service < ActiveRecord::Base
diff --git a/app/models/snippet.rb b/app/models/snippet.rb
index 644120453cf..f82d3a5d00f 100644
--- a/app/models/snippet.rb
+++ b/app/models/snippet.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Snippet < ActiveRecord::Base
   include Gitlab::VisibilityLevel
   include CacheMarkdownField
diff --git a/app/models/snippet_blob.rb b/app/models/snippet_blob.rb
index fa5fa151607..cf1ab089829 100644
--- a/app/models/snippet_blob.rb
+++ b/app/models/snippet_blob.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class SnippetBlob
   include BlobLike
 
diff --git a/app/models/spam_log.rb b/app/models/spam_log.rb
index 56a115d1db4..ef3f974b959 100644
--- a/app/models/spam_log.rb
+++ b/app/models/spam_log.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class SpamLog < ActiveRecord::Base
   belongs_to :user
 
diff --git a/app/models/subscription.rb b/app/models/subscription.rb
index 2f0c9640744..0f6ee0ddf7e 100644
--- a/app/models/subscription.rb
+++ b/app/models/subscription.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Subscription < ActiveRecord::Base
   belongs_to :user
   belongs_to :project
diff --git a/app/models/system_note_metadata.rb b/app/models/system_note_metadata.rb
index 1c2161accc4..c5c77bc8333 100644
--- a/app/models/system_note_metadata.rb
+++ b/app/models/system_note_metadata.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class SystemNoteMetadata < ActiveRecord::Base
   # These notes's action text might contain a reference that is external.
   # We should always force a deep validation upon references that are found
diff --git a/app/models/term_agreement.rb b/app/models/term_agreement.rb
index c317bd0c90b..9b3c8ac68bd 100644
--- a/app/models/term_agreement.rb
+++ b/app/models/term_agreement.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class TermAgreement < ActiveRecord::Base
   belongs_to :term, class_name: 'ApplicationSetting::Term'
   belongs_to :user
diff --git a/app/models/timelog.rb b/app/models/timelog.rb
index 659146f43e4..e04c644a53a 100644
--- a/app/models/timelog.rb
+++ b/app/models/timelog.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Timelog < ActiveRecord::Base
   validates :time_spent, :user, presence: true
   validate :issuable_id_is_present
diff --git a/app/models/todo.rb b/app/models/todo.rb
index a2ab405fdbe..5f5c2f9073d 100644
--- a/app/models/todo.rb
+++ b/app/models/todo.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Todo < ActiveRecord::Base
   include Sortable
 
diff --git a/app/models/tree.rb b/app/models/tree.rb
index 4c1856b67a8..3641c33254c 100644
--- a/app/models/tree.rb
+++ b/app/models/tree.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Tree
   include Gitlab::MarkupHelper
 
diff --git a/app/models/trending_project.rb b/app/models/trending_project.rb
index 27e3732da17..7b22e8cb760 100644
--- a/app/models/trending_project.rb
+++ b/app/models/trending_project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class TrendingProject < ActiveRecord::Base
   belongs_to :project
 
diff --git a/app/models/u2f_registration.rb b/app/models/u2f_registration.rb
index 808acec098f..37598173fd1 100644
--- a/app/models/u2f_registration.rb
+++ b/app/models/u2f_registration.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Registration information for U2F (universal 2nd factor) devices, like Yubikeys
 
 class U2fRegistration < ActiveRecord::Base
diff --git a/app/models/upload.rb b/app/models/upload.rb
index cf71a7b76fc..23bc9ca42fc 100644
--- a/app/models/upload.rb
+++ b/app/models/upload.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Upload < ActiveRecord::Base
   # Upper limit for foreground checksum processing
   CHECKSUM_THRESHOLD = 100.megabytes
diff --git a/app/models/user.rb b/app/models/user.rb
index 58429f8d607..0de8a6d057f 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'carrierwave/orm/activerecord'
 
 class User < ActiveRecord::Base
diff --git a/app/models/user_agent_detail.rb b/app/models/user_agent_detail.rb
index 2d05fdd3e54..e2b2e7f1df9 100644
--- a/app/models/user_agent_detail.rb
+++ b/app/models/user_agent_detail.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UserAgentDetail < ActiveRecord::Base
   belongs_to :subject, polymorphic: true # rubocop:disable Cop/PolymorphicAssociations
 
diff --git a/app/models/user_callout.rb b/app/models/user_callout.rb
index 9d461c6750a..97e955ace36 100644
--- a/app/models/user_callout.rb
+++ b/app/models/user_callout.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UserCallout < ActiveRecord::Base
   belongs_to :user
 
diff --git a/app/models/user_custom_attribute.rb b/app/models/user_custom_attribute.rb
index eff25b31f9b..e0ffe8ebbfd 100644
--- a/app/models/user_custom_attribute.rb
+++ b/app/models/user_custom_attribute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UserCustomAttribute < ActiveRecord::Base
   belongs_to :user
 
diff --git a/app/models/user_interacted_project.rb b/app/models/user_interacted_project.rb
index dd55a6acb79..ae6778e49be 100644
--- a/app/models/user_interacted_project.rb
+++ b/app/models/user_interacted_project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UserInteractedProject < ActiveRecord::Base
   belongs_to :user
   belongs_to :project
diff --git a/app/models/user_synced_attributes_metadata.rb b/app/models/user_synced_attributes_metadata.rb
index 688432a9d67..7115262942d 100644
--- a/app/models/user_synced_attributes_metadata.rb
+++ b/app/models/user_synced_attributes_metadata.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UserSyncedAttributesMetadata < ActiveRecord::Base
   belongs_to :user
 
diff --git a/app/models/users_star_project.rb b/app/models/users_star_project.rb
index 0dfe597317e..bdaf58ae1c1 100644
--- a/app/models/users_star_project.rb
+++ b/app/models/users_star_project.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class UsersStarProject < ActiveRecord::Base
   belongs_to :project, counter_cache: :star_count, touch: true
   belongs_to :user
diff --git a/app/models/wiki_directory.rb b/app/models/wiki_directory.rb
index 9340fc2dbbe..712ba79bbd2 100644
--- a/app/models/wiki_directory.rb
+++ b/app/models/wiki_directory.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class WikiDirectory
   include ActiveModel::Validations
 
diff --git a/app/models/wiki_page.rb b/app/models/wiki_page.rb
index 55243136140..33790afc35e 100644
--- a/app/models/wiki_page.rb
+++ b/app/models/wiki_page.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # rubocop:disable Rails/ActiveRecordAliases
 class WikiPage
   PageChangedError = Class.new(StandardError)
diff --git a/changelogs/unreleased/frozen-string-enable-app-models.yml b/changelogs/unreleased/frozen-string-enable-app-models.yml
new file mode 100644
index 00000000000..4c149ea55ef
--- /dev/null
+++ b/changelogs/unreleased/frozen-string-enable-app-models.yml
@@ -0,0 +1,5 @@
+---
+title: Enable frozen string in app/models/*.rb
+merge_request: 20851
+author: gfyoung
+type: performance
diff --git a/spec/controllers/admin/services_controller_spec.rb b/spec/controllers/admin/services_controller_spec.rb
index 701211c2586..4439ea4a533 100644
--- a/spec/controllers/admin/services_controller_spec.rb
+++ b/spec/controllers/admin/services_controller_spec.rb
@@ -13,7 +13,7 @@ describe Admin::ServicesController do
     Service.available_services_names.each do |service_name|
       context "#{service_name}" do
         let!(:service) do
-          service_template = service_name.concat("_service").camelize.constantize
+          service_template = "#{service_name}_service".camelize.constantize
           service_template.where(template: true).first_or_create
         end