diff --git a/changelogs/unreleased/frozen-string-lib-gitlab-even-even-more.yml b/changelogs/unreleased/frozen-string-lib-gitlab-even-even-more.yml
new file mode 100644
index 00000000000..e718d716647
--- /dev/null
+++ b/changelogs/unreleased/frozen-string-lib-gitlab-even-even-more.yml
@@ -0,0 +1,5 @@
+---
+title: Enable even more frozen string for lib/gitlab
+merge_request:
+author: gfyoung
+type: performance
diff --git a/lib/gitlab/hook_data/base_builder.rb b/lib/gitlab/hook_data/base_builder.rb
index 1a91301e8be..d54175bce81 100644
--- a/lib/gitlab/hook_data/base_builder.rb
+++ b/lib/gitlab/hook_data/base_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HookData
     class BaseBuilder
diff --git a/lib/gitlab/hook_data/issuable_builder.rb b/lib/gitlab/hook_data/issuable_builder.rb
index 65389835ad7..0803df65632 100644
--- a/lib/gitlab/hook_data/issuable_builder.rb
+++ b/lib/gitlab/hook_data/issuable_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HookData
     class IssuableBuilder < BaseBuilder
diff --git a/lib/gitlab/hook_data/issue_builder.rb b/lib/gitlab/hook_data/issue_builder.rb
index dd63db969f6..c99353b9d49 100644
--- a/lib/gitlab/hook_data/issue_builder.rb
+++ b/lib/gitlab/hook_data/issue_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HookData
     class IssueBuilder < BaseBuilder
diff --git a/lib/gitlab/hook_data/merge_request_builder.rb b/lib/gitlab/hook_data/merge_request_builder.rb
index 3aa6a4f3767..ad38e26e40a 100644
--- a/lib/gitlab/hook_data/merge_request_builder.rb
+++ b/lib/gitlab/hook_data/merge_request_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HookData
     class MergeRequestBuilder < BaseBuilder
diff --git a/lib/gitlab/hook_data/note_builder.rb b/lib/gitlab/hook_data/note_builder.rb
index 81873e345d5..ae30ef6364b 100644
--- a/lib/gitlab/hook_data/note_builder.rb
+++ b/lib/gitlab/hook_data/note_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HookData
     class NoteBuilder < BaseBuilder
diff --git a/lib/gitlab/hook_data/wiki_page_builder.rb b/lib/gitlab/hook_data/wiki_page_builder.rb
index 59c94a61cf2..67f06b1ca46 100644
--- a/lib/gitlab/hook_data/wiki_page_builder.rb
+++ b/lib/gitlab/hook_data/wiki_page_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HookData
     class WikiPageBuilder < BaseBuilder
diff --git a/lib/gitlab/i18n/metadata_entry.rb b/lib/gitlab/i18n/metadata_entry.rb
index 36fc1bcdcb7..3764e379681 100644
--- a/lib/gitlab/i18n/metadata_entry.rb
+++ b/lib/gitlab/i18n/metadata_entry.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module I18n
     class MetadataEntry
diff --git a/lib/gitlab/i18n/po_linter.rb b/lib/gitlab/i18n/po_linter.rb
index d8e7269a2c2..644ef8c8589 100644
--- a/lib/gitlab/i18n/po_linter.rb
+++ b/lib/gitlab/i18n/po_linter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module I18n
     class PoLinter
diff --git a/lib/gitlab/i18n/translation_entry.rb b/lib/gitlab/i18n/translation_entry.rb
index 54adb98f42d..19c10b2e402 100644
--- a/lib/gitlab/i18n/translation_entry.rb
+++ b/lib/gitlab/i18n/translation_entry.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module I18n
     class TranslationEntry
diff --git a/lib/gitlab/import/logger.rb b/lib/gitlab/import/logger.rb
index 8414954d141..ab3e822a4e9 100644
--- a/lib/gitlab/import/logger.rb
+++ b/lib/gitlab/import/logger.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Import
     class Logger < ::Gitlab::JsonLogger
diff --git a/lib/gitlab/import_export/after_export_strategies/base_after_export_strategy.rb b/lib/gitlab/import_export/after_export_strategies/base_after_export_strategy.rb
index 7cbf653dd97..d39b6fe5955 100644
--- a/lib/gitlab/import_export/after_export_strategies/base_after_export_strategy.rb
+++ b/lib/gitlab/import_export/after_export_strategies/base_after_export_strategy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     module AfterExportStrategies
diff --git a/lib/gitlab/import_export/after_export_strategies/download_notification_strategy.rb b/lib/gitlab/import_export/after_export_strategies/download_notification_strategy.rb
index 4371a7eff56..1b391314a74 100644
--- a/lib/gitlab/import_export/after_export_strategies/download_notification_strategy.rb
+++ b/lib/gitlab/import_export/after_export_strategies/download_notification_strategy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     module AfterExportStrategies
diff --git a/lib/gitlab/import_export/after_export_strategies/web_upload_strategy.rb b/lib/gitlab/import_export/after_export_strategies/web_upload_strategy.rb
index 4f29bdcea2c..b30900f7c61 100644
--- a/lib/gitlab/import_export/after_export_strategies/web_upload_strategy.rb
+++ b/lib/gitlab/import_export/after_export_strategies/web_upload_strategy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     module AfterExportStrategies
diff --git a/lib/gitlab/import_export/after_export_strategy_builder.rb b/lib/gitlab/import_export/after_export_strategy_builder.rb
index 7eabcae2380..37394f46a99 100644
--- a/lib/gitlab/import_export/after_export_strategy_builder.rb
+++ b/lib/gitlab/import_export/after_export_strategy_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class AfterExportStrategyBuilder
diff --git a/lib/gitlab/import_export/attribute_cleaner.rb b/lib/gitlab/import_export/attribute_cleaner.rb
index 7c9fc5c15bb..93b37b7bc5f 100644
--- a/lib/gitlab/import_export/attribute_cleaner.rb
+++ b/lib/gitlab/import_export/attribute_cleaner.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class AttributeCleaner
diff --git a/lib/gitlab/import_export/attributes_finder.rb b/lib/gitlab/import_export/attributes_finder.rb
index 0c8fda07294..409243e68a5 100644
--- a/lib/gitlab/import_export/attributes_finder.rb
+++ b/lib/gitlab/import_export/attributes_finder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class AttributesFinder
diff --git a/lib/gitlab/import_export/avatar_restorer.rb b/lib/gitlab/import_export/avatar_restorer.rb
index 17796430811..be1b97bd7a7 100644
--- a/lib/gitlab/import_export/avatar_restorer.rb
+++ b/lib/gitlab/import_export/avatar_restorer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class AvatarRestorer
diff --git a/lib/gitlab/import_export/avatar_saver.rb b/lib/gitlab/import_export/avatar_saver.rb
index 6ffebf83dd2..47ca898c690 100644
--- a/lib/gitlab/import_export/avatar_saver.rb
+++ b/lib/gitlab/import_export/avatar_saver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class AvatarSaver
diff --git a/lib/gitlab/import_export/command_line_util.rb b/lib/gitlab/import_export/command_line_util.rb
index 3adc44f8044..c9e2a6a78d9 100644
--- a/lib/gitlab/import_export/command_line_util.rb
+++ b/lib/gitlab/import_export/command_line_util.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     module CommandLineUtil
diff --git a/lib/gitlab/import_export/error.rb b/lib/gitlab/import_export/error.rb
index 788eedf2686..454dc778b6b 100644
--- a/lib/gitlab/import_export/error.rb
+++ b/lib/gitlab/import_export/error.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     Error = Class.new(StandardError)
diff --git a/lib/gitlab/import_export/file_importer.rb b/lib/gitlab/import_export/file_importer.rb
index 7fd66b4e244..05432f433e7 100644
--- a/lib/gitlab/import_export/file_importer.rb
+++ b/lib/gitlab/import_export/file_importer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class FileImporter
diff --git a/lib/gitlab/import_export/group_project_object_builder.rb b/lib/gitlab/import_export/group_project_object_builder.rb
index 6c2af770119..1c62591ed5a 100644
--- a/lib/gitlab/import_export/group_project_object_builder.rb
+++ b/lib/gitlab/import_export/group_project_object_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     # Given a class, it finds or creates a new object
diff --git a/lib/gitlab/import_export/hash_util.rb b/lib/gitlab/import_export/hash_util.rb
index d4adeeb3797..b6ce89a973b 100644
--- a/lib/gitlab/import_export/hash_util.rb
+++ b/lib/gitlab/import_export/hash_util.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class HashUtil
diff --git a/lib/gitlab/import_export/importer.rb b/lib/gitlab/import_export/importer.rb
index 72d5b9b830c..767f1b5de0e 100644
--- a/lib/gitlab/import_export/importer.rb
+++ b/lib/gitlab/import_export/importer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class Importer
diff --git a/lib/gitlab/import_export/json_hash_builder.rb b/lib/gitlab/import_export/json_hash_builder.rb
index b48f63bcd7e..477499e1688 100644
--- a/lib/gitlab/import_export/json_hash_builder.rb
+++ b/lib/gitlab/import_export/json_hash_builder.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     # Generates a hash that conforms with http://apidock.com/rails/Hash/to_json
diff --git a/lib/gitlab/import_export/lfs_restorer.rb b/lib/gitlab/import_export/lfs_restorer.rb
index b28c3c161b7..345c7880e30 100644
--- a/lib/gitlab/import_export/lfs_restorer.rb
+++ b/lib/gitlab/import_export/lfs_restorer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class LfsRestorer
diff --git a/lib/gitlab/import_export/lfs_saver.rb b/lib/gitlab/import_export/lfs_saver.rb
index 29410e2331c..954f6f00078 100644
--- a/lib/gitlab/import_export/lfs_saver.rb
+++ b/lib/gitlab/import_export/lfs_saver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class LfsSaver
diff --git a/lib/gitlab/import_export/members_mapper.rb b/lib/gitlab/import_export/members_mapper.rb
index bcbaf00e11b..6be95a16513 100644
--- a/lib/gitlab/import_export/members_mapper.rb
+++ b/lib/gitlab/import_export/members_mapper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class MembersMapper
diff --git a/lib/gitlab/import_export/merge_request_parser.rb b/lib/gitlab/import_export/merge_request_parser.rb
index 62a1833b39c..040a70d6775 100644
--- a/lib/gitlab/import_export/merge_request_parser.rb
+++ b/lib/gitlab/import_export/merge_request_parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class MergeRequestParser
diff --git a/lib/gitlab/import_export/project_tree_restorer.rb b/lib/gitlab/import_export/project_tree_restorer.rb
index 99581eb0416..8cd4efd91cc 100644
--- a/lib/gitlab/import_export/project_tree_restorer.rb
+++ b/lib/gitlab/import_export/project_tree_restorer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class ProjectTreeRestorer
diff --git a/lib/gitlab/import_export/project_tree_saver.rb b/lib/gitlab/import_export/project_tree_saver.rb
index 5510c0b8b2f..29f2dc80813 100644
--- a/lib/gitlab/import_export/project_tree_saver.rb
+++ b/lib/gitlab/import_export/project_tree_saver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class ProjectTreeSaver
diff --git a/lib/gitlab/import_export/reader.rb b/lib/gitlab/import_export/reader.rb
index e621c40fc7a..bc0d18e03fa 100644
--- a/lib/gitlab/import_export/reader.rb
+++ b/lib/gitlab/import_export/reader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class Reader
diff --git a/lib/gitlab/import_export/relation_factory.rb b/lib/gitlab/import_export/relation_factory.rb
index 2486b1e4921..097c7653754 100644
--- a/lib/gitlab/import_export/relation_factory.rb
+++ b/lib/gitlab/import_export/relation_factory.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class RelationFactory
@@ -211,7 +213,7 @@ module Gitlab
 
       def update_note_for_missing_author(author_name)
         @relation_hash['note'] = '*Blank note*' if @relation_hash['note'].blank?
-        @relation_hash['note'] += missing_author_note(@relation_hash['updated_at'], author_name)
+        @relation_hash['note'] = "#{@relation_hash['note']}#{missing_author_note(@relation_hash['updated_at'], author_name)}"
       end
 
       def admin_user?
diff --git a/lib/gitlab/import_export/repo_restorer.rb b/lib/gitlab/import_export/repo_restorer.rb
index 5a9bbceac67..921a06b4023 100644
--- a/lib/gitlab/import_export/repo_restorer.rb
+++ b/lib/gitlab/import_export/repo_restorer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class RepoRestorer
diff --git a/lib/gitlab/import_export/repo_saver.rb b/lib/gitlab/import_export/repo_saver.rb
index 0c224bd1971..a60618dfcec 100644
--- a/lib/gitlab/import_export/repo_saver.rb
+++ b/lib/gitlab/import_export/repo_saver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class RepoSaver
diff --git a/lib/gitlab/import_export/saver.rb b/lib/gitlab/import_export/saver.rb
index 59a74083395..72f575db095 100644
--- a/lib/gitlab/import_export/saver.rb
+++ b/lib/gitlab/import_export/saver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class Saver
diff --git a/lib/gitlab/import_export/shared.rb b/lib/gitlab/import_export/shared.rb
index 6d7c36ce38b..c13e6c1d83b 100644
--- a/lib/gitlab/import_export/shared.rb
+++ b/lib/gitlab/import_export/shared.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class Shared
diff --git a/lib/gitlab/import_export/statistics_restorer.rb b/lib/gitlab/import_export/statistics_restorer.rb
index bcdd9c12c85..3fafb01c37c 100644
--- a/lib/gitlab/import_export/statistics_restorer.rb
+++ b/lib/gitlab/import_export/statistics_restorer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class StatisticsRestorer
diff --git a/lib/gitlab/import_export/uploads_manager.rb b/lib/gitlab/import_export/uploads_manager.rb
index 8511319cb1c..474e9d45566 100644
--- a/lib/gitlab/import_export/uploads_manager.rb
+++ b/lib/gitlab/import_export/uploads_manager.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class UploadsManager
diff --git a/lib/gitlab/import_export/uploads_restorer.rb b/lib/gitlab/import_export/uploads_restorer.rb
index b4313ff4cb4..5f422dcbefa 100644
--- a/lib/gitlab/import_export/uploads_restorer.rb
+++ b/lib/gitlab/import_export/uploads_restorer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class UploadsRestorer < UploadsSaver
diff --git a/lib/gitlab/import_export/uploads_saver.rb b/lib/gitlab/import_export/uploads_saver.rb
index 0275f686c5e..be1066c30b2 100644
--- a/lib/gitlab/import_export/uploads_saver.rb
+++ b/lib/gitlab/import_export/uploads_saver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class UploadsSaver
diff --git a/lib/gitlab/import_export/version_checker.rb b/lib/gitlab/import_export/version_checker.rb
index bd3c3ee3b2f..6d978d00ea5 100644
--- a/lib/gitlab/import_export/version_checker.rb
+++ b/lib/gitlab/import_export/version_checker.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class VersionChecker
diff --git a/lib/gitlab/import_export/version_saver.rb b/lib/gitlab/import_export/version_saver.rb
index 7cf88298642..8230c0f1e77 100644
--- a/lib/gitlab/import_export/version_saver.rb
+++ b/lib/gitlab/import_export/version_saver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class VersionSaver
diff --git a/lib/gitlab/import_export/wiki_repo_saver.rb b/lib/gitlab/import_export/wiki_repo_saver.rb
index 2fd62c0fc7b..7303bcf61a4 100644
--- a/lib/gitlab/import_export/wiki_repo_saver.rb
+++ b/lib/gitlab/import_export/wiki_repo_saver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class WikiRepoSaver < RepoSaver
diff --git a/lib/gitlab/import_export/wiki_restorer.rb b/lib/gitlab/import_export/wiki_restorer.rb
index f33bfb332ab..28b5e7449cd 100644
--- a/lib/gitlab/import_export/wiki_restorer.rb
+++ b/lib/gitlab/import_export/wiki_restorer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ImportExport
     class WikiRestorer < RepoRestorer
diff --git a/lib/gitlab/kubernetes/config_map.rb b/lib/gitlab/kubernetes/config_map.rb
index 9e55dae137c..0bcaaa03974 100644
--- a/lib/gitlab/kubernetes/config_map.rb
+++ b/lib/gitlab/kubernetes/config_map.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     class ConfigMap
diff --git a/lib/gitlab/kubernetes/helm.rb b/lib/gitlab/kubernetes/helm.rb
index 5a22b5e3364..03d38ec78fd 100644
--- a/lib/gitlab/kubernetes/helm.rb
+++ b/lib/gitlab/kubernetes/helm.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     module Helm
diff --git a/lib/gitlab/kubernetes/helm/api.rb b/lib/gitlab/kubernetes/helm/api.rb
index 7c026ac9e68..fd3d187cbc3 100644
--- a/lib/gitlab/kubernetes/helm/api.rb
+++ b/lib/gitlab/kubernetes/helm/api.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     module Helm
diff --git a/lib/gitlab/kubernetes/helm/base_command.rb b/lib/gitlab/kubernetes/helm/base_command.rb
index f2ce24fefa1..2bcb428b25d 100644
--- a/lib/gitlab/kubernetes/helm/base_command.rb
+++ b/lib/gitlab/kubernetes/helm/base_command.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     module Helm
diff --git a/lib/gitlab/kubernetes/helm/client_command.rb b/lib/gitlab/kubernetes/helm/client_command.rb
index 72bafc07bf0..9940272a8bf 100644
--- a/lib/gitlab/kubernetes/helm/client_command.rb
+++ b/lib/gitlab/kubernetes/helm/client_command.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     module Helm
diff --git a/lib/gitlab/kubernetes/helm/init_command.rb b/lib/gitlab/kubernetes/helm/init_command.rb
index 6691080deca..88ed8572ffc 100644
--- a/lib/gitlab/kubernetes/helm/init_command.rb
+++ b/lib/gitlab/kubernetes/helm/init_command.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     module Helm
diff --git a/lib/gitlab/kubernetes/helm/install_command.rb b/lib/gitlab/kubernetes/helm/install_command.rb
index 52700b5dc09..961485005f7 100644
--- a/lib/gitlab/kubernetes/helm/install_command.rb
+++ b/lib/gitlab/kubernetes/helm/install_command.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     module Helm
diff --git a/lib/gitlab/kubernetes/helm/pod.rb b/lib/gitlab/kubernetes/helm/pod.rb
index e9c621d96f0..75484f80070 100644
--- a/lib/gitlab/kubernetes/helm/pod.rb
+++ b/lib/gitlab/kubernetes/helm/pod.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     module Helm
diff --git a/lib/gitlab/kubernetes/namespace.rb b/lib/gitlab/kubernetes/namespace.rb
index 783c8a24741..919f19c86d7 100644
--- a/lib/gitlab/kubernetes/namespace.rb
+++ b/lib/gitlab/kubernetes/namespace.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     class Namespace
diff --git a/lib/gitlab/kubernetes/pod.rb b/lib/gitlab/kubernetes/pod.rb
index f3842cdf762..81317e532b2 100644
--- a/lib/gitlab/kubernetes/pod.rb
+++ b/lib/gitlab/kubernetes/pod.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Kubernetes
     module Pod
diff --git a/lib/gitlab/legacy_github_import/base_formatter.rb b/lib/gitlab/legacy_github_import/base_formatter.rb
index 11d1300e51e..0b19cf742ed 100644
--- a/lib/gitlab/legacy_github_import/base_formatter.rb
+++ b/lib/gitlab/legacy_github_import/base_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class BaseFormatter
diff --git a/lib/gitlab/legacy_github_import/branch_formatter.rb b/lib/gitlab/legacy_github_import/branch_formatter.rb
index 80fe1d67209..1177751457f 100644
--- a/lib/gitlab/legacy_github_import/branch_formatter.rb
+++ b/lib/gitlab/legacy_github_import/branch_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class BranchFormatter < BaseFormatter
diff --git a/lib/gitlab/legacy_github_import/client.rb b/lib/gitlab/legacy_github_import/client.rb
index d8ed0ebca9d..bc952147667 100644
--- a/lib/gitlab/legacy_github_import/client.rb
+++ b/lib/gitlab/legacy_github_import/client.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class Client
diff --git a/lib/gitlab/legacy_github_import/comment_formatter.rb b/lib/gitlab/legacy_github_import/comment_formatter.rb
index d2c7a8ae9f4..d83cc4f6b3c 100644
--- a/lib/gitlab/legacy_github_import/comment_formatter.rb
+++ b/lib/gitlab/legacy_github_import/comment_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class CommentFormatter < BaseFormatter
diff --git a/lib/gitlab/legacy_github_import/importer.rb b/lib/gitlab/legacy_github_import/importer.rb
index c5bde681365..43695451b87 100644
--- a/lib/gitlab/legacy_github_import/importer.rb
+++ b/lib/gitlab/legacy_github_import/importer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class Importer
diff --git a/lib/gitlab/legacy_github_import/issuable_formatter.rb b/lib/gitlab/legacy_github_import/issuable_formatter.rb
index 7db4a54267e..1a0aefbbd62 100644
--- a/lib/gitlab/legacy_github_import/issuable_formatter.rb
+++ b/lib/gitlab/legacy_github_import/issuable_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class IssuableFormatter < BaseFormatter
diff --git a/lib/gitlab/legacy_github_import/issue_formatter.rb b/lib/gitlab/legacy_github_import/issue_formatter.rb
index 4c8825ccf19..2f46e2e30d1 100644
--- a/lib/gitlab/legacy_github_import/issue_formatter.rb
+++ b/lib/gitlab/legacy_github_import/issue_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class IssueFormatter < IssuableFormatter
diff --git a/lib/gitlab/legacy_github_import/label_formatter.rb b/lib/gitlab/legacy_github_import/label_formatter.rb
index e9663650903..89200e794d8 100644
--- a/lib/gitlab/legacy_github_import/label_formatter.rb
+++ b/lib/gitlab/legacy_github_import/label_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class LabelFormatter < BaseFormatter
diff --git a/lib/gitlab/legacy_github_import/milestone_formatter.rb b/lib/gitlab/legacy_github_import/milestone_formatter.rb
index a565294384d..2fe1b4258d3 100644
--- a/lib/gitlab/legacy_github_import/milestone_formatter.rb
+++ b/lib/gitlab/legacy_github_import/milestone_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class MilestoneFormatter < BaseFormatter
diff --git a/lib/gitlab/legacy_github_import/project_creator.rb b/lib/gitlab/legacy_github_import/project_creator.rb
index 5e96eb16754..ca1a1b8e9bd 100644
--- a/lib/gitlab/legacy_github_import/project_creator.rb
+++ b/lib/gitlab/legacy_github_import/project_creator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class ProjectCreator
diff --git a/lib/gitlab/legacy_github_import/pull_request_formatter.rb b/lib/gitlab/legacy_github_import/pull_request_formatter.rb
index 94c2e99066a..5b847f13d4a 100644
--- a/lib/gitlab/legacy_github_import/pull_request_formatter.rb
+++ b/lib/gitlab/legacy_github_import/pull_request_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class PullRequestFormatter < IssuableFormatter
diff --git a/lib/gitlab/legacy_github_import/release_formatter.rb b/lib/gitlab/legacy_github_import/release_formatter.rb
index 3ed9d4f76da..8c0c17780ca 100644
--- a/lib/gitlab/legacy_github_import/release_formatter.rb
+++ b/lib/gitlab/legacy_github_import/release_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class ReleaseFormatter < BaseFormatter
diff --git a/lib/gitlab/legacy_github_import/user_formatter.rb b/lib/gitlab/legacy_github_import/user_formatter.rb
index 3794380e2d0..ec0e221b1ff 100644
--- a/lib/gitlab/legacy_github_import/user_formatter.rb
+++ b/lib/gitlab/legacy_github_import/user_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class UserFormatter
diff --git a/lib/gitlab/legacy_github_import/wiki_formatter.rb b/lib/gitlab/legacy_github_import/wiki_formatter.rb
index 27f45875c7c..ea52be5ee0f 100644
--- a/lib/gitlab/legacy_github_import/wiki_formatter.rb
+++ b/lib/gitlab/legacy_github_import/wiki_formatter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module LegacyGithubImport
     class WikiFormatter
diff --git a/lib/gitlab/manifest_import/manifest.rb b/lib/gitlab/manifest_import/manifest.rb
index b69b9ac4b64..7208fe5bbc5 100644
--- a/lib/gitlab/manifest_import/manifest.rb
+++ b/lib/gitlab/manifest_import/manifest.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Class to parse manifest file and build a list of repositories for import
 #
 # <manifest>
diff --git a/lib/gitlab/manifest_import/project_creator.rb b/lib/gitlab/manifest_import/project_creator.rb
index b5967c93735..837d65e5f7c 100644
--- a/lib/gitlab/manifest_import/project_creator.rb
+++ b/lib/gitlab/manifest_import/project_creator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module ManifestImport
     class ProjectCreator
diff --git a/lib/gitlab/metrics/background_transaction.rb b/lib/gitlab/metrics/background_transaction.rb
index 5919ebb1493..fe1722b1095 100644
--- a/lib/gitlab/metrics/background_transaction.rb
+++ b/lib/gitlab/metrics/background_transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     class BackgroundTransaction < Transaction
diff --git a/lib/gitlab/metrics/delta.rb b/lib/gitlab/metrics/delta.rb
index bcf28eed84d..ab2d9e46390 100644
--- a/lib/gitlab/metrics/delta.rb
+++ b/lib/gitlab/metrics/delta.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Class for calculating the difference between two numeric values.
diff --git a/lib/gitlab/metrics/influx_db.rb b/lib/gitlab/metrics/influx_db.rb
index ce9d3ec3de4..1359e973590 100644
--- a/lib/gitlab/metrics/influx_db.rb
+++ b/lib/gitlab/metrics/influx_db.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     module InfluxDb
diff --git a/lib/gitlab/metrics/instrumentation.rb b/lib/gitlab/metrics/instrumentation.rb
index 023e9963493..651e241362c 100644
--- a/lib/gitlab/metrics/instrumentation.rb
+++ b/lib/gitlab/metrics/instrumentation.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Module for instrumenting methods.
diff --git a/lib/gitlab/metrics/method_call.rb b/lib/gitlab/metrics/method_call.rb
index f3290e3149c..85438011cb9 100644
--- a/lib/gitlab/metrics/method_call.rb
+++ b/lib/gitlab/metrics/method_call.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Class for tracking timing information about method calls
diff --git a/lib/gitlab/metrics/methods.rb b/lib/gitlab/metrics/methods.rb
index f79eb0cd1bf..447d03bfca4 100644
--- a/lib/gitlab/metrics/methods.rb
+++ b/lib/gitlab/metrics/methods.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # rubocop:disable Style/ClassVars
 
 module Gitlab
diff --git a/lib/gitlab/metrics/methods/metric_options.rb b/lib/gitlab/metrics/methods/metric_options.rb
index 70e122d4e15..8e6ceb74c09 100644
--- a/lib/gitlab/metrics/methods/metric_options.rb
+++ b/lib/gitlab/metrics/methods/metric_options.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     module Methods
diff --git a/lib/gitlab/metrics/metric.rb b/lib/gitlab/metrics/metric.rb
index bd0afe53c51..9e4d70a71ff 100644
--- a/lib/gitlab/metrics/metric.rb
+++ b/lib/gitlab/metrics/metric.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Class for storing details of a single metric (label, value, etc).
diff --git a/lib/gitlab/metrics/null_metric.rb b/lib/gitlab/metrics/null_metric.rb
index aabada5c21a..7dbd2a1f8e3 100644
--- a/lib/gitlab/metrics/null_metric.rb
+++ b/lib/gitlab/metrics/null_metric.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Mocks ::Prometheus::Client::Metric and all derived metrics
diff --git a/lib/gitlab/metrics/prometheus.rb b/lib/gitlab/metrics/prometheus.rb
index d41a855bff1..cab1edab48f 100644
--- a/lib/gitlab/metrics/prometheus.rb
+++ b/lib/gitlab/metrics/prometheus.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'prometheus/client'
 
 module Gitlab
diff --git a/lib/gitlab/metrics/rack_middleware.rb b/lib/gitlab/metrics/rack_middleware.rb
index 2d45765df3f..9aa97515961 100644
--- a/lib/gitlab/metrics/rack_middleware.rb
+++ b/lib/gitlab/metrics/rack_middleware.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Rack middleware for tracking Rails and Grape requests.
diff --git a/lib/gitlab/metrics/requests_rack_middleware.rb b/lib/gitlab/metrics/requests_rack_middleware.rb
index 0dc19f31d03..74c956ab5af 100644
--- a/lib/gitlab/metrics/requests_rack_middleware.rb
+++ b/lib/gitlab/metrics/requests_rack_middleware.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     class RequestsRackMiddleware
diff --git a/lib/gitlab/metrics/samplers/base_sampler.rb b/lib/gitlab/metrics/samplers/base_sampler.rb
index 37f90c4673d..6a062e93f0f 100644
--- a/lib/gitlab/metrics/samplers/base_sampler.rb
+++ b/lib/gitlab/metrics/samplers/base_sampler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'logger'
 
 module Gitlab
diff --git a/lib/gitlab/metrics/samplers/influx_sampler.rb b/lib/gitlab/metrics/samplers/influx_sampler.rb
index ad97632e4eb..c4c38b23a55 100644
--- a/lib/gitlab/metrics/samplers/influx_sampler.rb
+++ b/lib/gitlab/metrics/samplers/influx_sampler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     module Samplers
diff --git a/lib/gitlab/metrics/samplers/ruby_sampler.rb b/lib/gitlab/metrics/samplers/ruby_sampler.rb
index 7b2b3bedf04..232a58a7d69 100644
--- a/lib/gitlab/metrics/samplers/ruby_sampler.rb
+++ b/lib/gitlab/metrics/samplers/ruby_sampler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'prometheus/client/support/unicorn'
 
 module Gitlab
diff --git a/lib/gitlab/metrics/samplers/unicorn_sampler.rb b/lib/gitlab/metrics/samplers/unicorn_sampler.rb
index ea325651fbb..4c4ec026823 100644
--- a/lib/gitlab/metrics/samplers/unicorn_sampler.rb
+++ b/lib/gitlab/metrics/samplers/unicorn_sampler.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     module Samplers
diff --git a/lib/gitlab/metrics/sidekiq_metrics_exporter.rb b/lib/gitlab/metrics/sidekiq_metrics_exporter.rb
index 47b4af5d649..56e106b9612 100644
--- a/lib/gitlab/metrics/sidekiq_metrics_exporter.rb
+++ b/lib/gitlab/metrics/sidekiq_metrics_exporter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'webrick'
 require 'prometheus/client/rack/exporter'
 
diff --git a/lib/gitlab/metrics/sidekiq_middleware.rb b/lib/gitlab/metrics/sidekiq_middleware.rb
index df4bdf16847..0b4485feea9 100644
--- a/lib/gitlab/metrics/sidekiq_middleware.rb
+++ b/lib/gitlab/metrics/sidekiq_middleware.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Sidekiq middleware for tracking jobs.
diff --git a/lib/gitlab/metrics/subscribers/action_view.rb b/lib/gitlab/metrics/subscribers/action_view.rb
index b600e8a2a50..c068f8017fd 100644
--- a/lib/gitlab/metrics/subscribers/action_view.rb
+++ b/lib/gitlab/metrics/subscribers/action_view.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     module Subscribers
diff --git a/lib/gitlab/metrics/subscribers/active_record.rb b/lib/gitlab/metrics/subscribers/active_record.rb
index 04107296ae3..a02dd850582 100644
--- a/lib/gitlab/metrics/subscribers/active_record.rb
+++ b/lib/gitlab/metrics/subscribers/active_record.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     module Subscribers
diff --git a/lib/gitlab/metrics/subscribers/rails_cache.rb b/lib/gitlab/metrics/subscribers/rails_cache.rb
index 250897a79c2..f633e1a9d7c 100644
--- a/lib/gitlab/metrics/subscribers/rails_cache.rb
+++ b/lib/gitlab/metrics/subscribers/rails_cache.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     module Subscribers
diff --git a/lib/gitlab/metrics/system.rb b/lib/gitlab/metrics/system.rb
index e60e245cf89..426496855e3 100644
--- a/lib/gitlab/metrics/system.rb
+++ b/lib/gitlab/metrics/system.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Module for gathering system/process statistics such as the memory usage.
diff --git a/lib/gitlab/metrics/transaction.rb b/lib/gitlab/metrics/transaction.rb
index 9f903e96585..468d7cb56fc 100644
--- a/lib/gitlab/metrics/transaction.rb
+++ b/lib/gitlab/metrics/transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     # Class for storing metrics information of a single transaction.
diff --git a/lib/gitlab/metrics/web_transaction.rb b/lib/gitlab/metrics/web_transaction.rb
index 723ca576aab..b2a43d46fb2 100644
--- a/lib/gitlab/metrics/web_transaction.rb
+++ b/lib/gitlab/metrics/web_transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Metrics
     class WebTransaction < Transaction
@@ -40,7 +42,7 @@ module Gitlab
         # increasing the cardinality of our metrics, we limit the number of
         # possible suffixes.
         if suffix && ALLOWED_SUFFIXES.include?(suffix)
-          action += ".#{suffix}"
+          action = "#{action}.#{suffix}"
         end
 
         { controller: controller.class.name, action: action }
diff --git a/lib/gitlab/middleware/go.rb b/lib/gitlab/middleware/go.rb
index 6943567fb6d..d1a87c3b3bb 100644
--- a/lib/gitlab/middleware/go.rb
+++ b/lib/gitlab/middleware/go.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # A dumb middleware that returns a Go HTML document if the go-get=1 query string
 # is used irrespective if the namespace/project exists
 module Gitlab
diff --git a/lib/gitlab/middleware/multipart.rb b/lib/gitlab/middleware/multipart.rb
index 10cb1e7127e..84c2f0d5720 100644
--- a/lib/gitlab/middleware/multipart.rb
+++ b/lib/gitlab/middleware/multipart.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitlab::Middleware::Multipart - a Rack::Multipart replacement
 #
 # Rack::Multipart leaves behind tempfiles in /tmp and uses valuable Ruby
diff --git a/lib/gitlab/middleware/rails_queue_duration.rb b/lib/gitlab/middleware/rails_queue_duration.rb
index bc70b2459ef..96c6a0a7d28 100644
--- a/lib/gitlab/middleware/rails_queue_duration.rb
+++ b/lib/gitlab/middleware/rails_queue_duration.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This Rack middleware is intended to measure the latency between
 # gitlab-workhorse forwarding a request to the Rails application and the
 # time this middleware is reached.
diff --git a/lib/gitlab/middleware/read_only.rb b/lib/gitlab/middleware/read_only.rb
index 7f63e39b3aa..83c52a6c6e0 100644
--- a/lib/gitlab/middleware/read_only.rb
+++ b/lib/gitlab/middleware/read_only.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Middleware
     class ReadOnly
diff --git a/lib/gitlab/middleware/read_only/controller.rb b/lib/gitlab/middleware/read_only/controller.rb
index 8dca431c005..89941a9efa0 100644
--- a/lib/gitlab/middleware/read_only/controller.rb
+++ b/lib/gitlab/middleware/read_only/controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Middleware
     class ReadOnly
diff --git a/lib/gitlab/middleware/release_env.rb b/lib/gitlab/middleware/release_env.rb
index bfe8e113b5e..849cf8f759b 100644
--- a/lib/gitlab/middleware/release_env.rb
+++ b/lib/gitlab/middleware/release_env.rb
@@ -1,4 +1,7 @@
-module Gitlab # rubocop:disable Naming/FileName
+# rubocop:disable Naming/FileName
+# frozen_string_literal: true
+
+module Gitlab
   module Middleware
     # Some of middleware would hold env for no good reason even after the
     # request had already been processed, and we could not garbage collect
diff --git a/lib/gitlab/middleware/static.rb b/lib/gitlab/middleware/static.rb
index aa1e9dc0fdb..972fed2134c 100644
--- a/lib/gitlab/middleware/static.rb
+++ b/lib/gitlab/middleware/static.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Middleware
     class Static < ActionDispatch::Static