Enable even more frozen string in lib/gitlabrepo-forks/gitlab-ce-frozen-string-lib-gitlab-even-more

Enables frozen string for the following:

* lib/gitlab/fogbugz_import/**/*.rb
* lib/gitlab/gfm/**/*.rb
* lib/gitlab/git/**/*.rb
* lib/gitlab/gitaly_client/**/*.rb
* lib/gitlab/gitlab_import/**/*.rb
* lib/gitlab/google_code_import/**/*.rb
* lib/gitlab/gpg/**/*.rb
* lib/gitlab/grape_logging/**/*.rb
* lib/gitlab/graphql/**/*.rb
* lib/gitlab/graphs/**/*.rb
* lib/gitlab/hashed_storage/**/*.rb
* lib/gitlab/health_checks/**/*.rb

Partially address gitlab-org/gitlab-ce#47424.

104 files changed, 237 insertions, 22 deletions

diff --git a/changelogs/unreleased/frozen-string-lib-gitlab-even-more.yml b/changelogs/unreleased/frozen-string-lib-gitlab-even-more.yml
new file mode 100644
index 00000000000..cfbc4ced635
--- /dev/null
+++ b/changelogs/unreleased/frozen-string-lib-gitlab-even-more.yml
@@ -0,0 +1,5 @@
+---
+title: Enable even more frozen string in lib/gitlab/**/*.rb
+merge_request:
+author: gfyoung
+type: performance
diff --git a/lib/gitlab/fogbugz_import/client.rb b/lib/gitlab/fogbugz_import/client.rb
index acb000e3e23..dd747a79673 100644
--- a/lib/gitlab/fogbugz_import/client.rb
+++ b/lib/gitlab/fogbugz_import/client.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'fogbugz'
 
 module Gitlab
diff --git a/lib/gitlab/fogbugz_import/importer.rb b/lib/gitlab/fogbugz_import/importer.rb
index 98ea5b309a1..431911d1eee 100644
--- a/lib/gitlab/fogbugz_import/importer.rb
+++ b/lib/gitlab/fogbugz_import/importer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module FogbugzImport
     class Importer
diff --git a/lib/gitlab/fogbugz_import/project_creator.rb b/lib/gitlab/fogbugz_import/project_creator.rb
index 1918d5b208d..3c71031a8d9 100644
--- a/lib/gitlab/fogbugz_import/project_creator.rb
+++ b/lib/gitlab/fogbugz_import/project_creator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module FogbugzImport
     class ProjectCreator
diff --git a/lib/gitlab/fogbugz_import/repository.rb b/lib/gitlab/fogbugz_import/repository.rb
index d1dc63db2b2..b958dcf6cbf 100644
--- a/lib/gitlab/fogbugz_import/repository.rb
+++ b/lib/gitlab/fogbugz_import/repository.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module FogbugzImport
     class Repository
diff --git a/lib/gitlab/gfm/reference_rewriter.rb b/lib/gitlab/gfm/reference_rewriter.rb
index 641446b52a5..08d7db49ad7 100644
--- a/lib/gitlab/gfm/reference_rewriter.rb
+++ b/lib/gitlab/gfm/reference_rewriter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Gfm
     ##
diff --git a/lib/gitlab/gfm/uploads_rewriter.rb b/lib/gitlab/gfm/uploads_rewriter.rb
index b767c8a278d..3f06badf5d9 100644
--- a/lib/gitlab/gfm/uploads_rewriter.rb
+++ b/lib/gitlab/gfm/uploads_rewriter.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'fileutils'
 
 module Gitlab
diff --git a/lib/gitlab/git/attributes_at_ref_parser.rb b/lib/gitlab/git/attributes_at_ref_parser.rb
index 26b5bd520d5..cbddf836ce8 100644
--- a/lib/gitlab/git/attributes_at_ref_parser.rb
+++ b/lib/gitlab/git/attributes_at_ref_parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     # Parses root .gitattributes file at a given ref
diff --git a/lib/gitlab/git/attributes_parser.rb b/lib/gitlab/git/attributes_parser.rb
index 08f4d7d4f5c..8b9d74ae8e7 100644
--- a/lib/gitlab/git/attributes_parser.rb
+++ b/lib/gitlab/git/attributes_parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     # Class for parsing Git attribute files and extracting the attributes for
diff --git a/lib/gitlab/git/blame.rb b/lib/gitlab/git/blame.rb
index e25e15f5c80..b118eda37f8 100644
--- a/lib/gitlab/git/blame.rb
+++ b/lib/gitlab/git/blame.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Blame
diff --git a/lib/gitlab/git/blob.rb b/lib/gitlab/git/blob.rb
index 0bd1d3420a2..9dd1c484d59 100644
--- a/lib/gitlab/git/blob.rb
+++ b/lib/gitlab/git/blob.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitaly note: JV: seems to be completely migrated (behind feature flags).
 
 module Gitlab
diff --git a/lib/gitlab/git/branch.rb b/lib/gitlab/git/branch.rb
index 6351cfb83e3..9447cfa0fb6 100644
--- a/lib/gitlab/git/branch.rb
+++ b/lib/gitlab/git/branch.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Branch < Ref
diff --git a/lib/gitlab/git/commit.rb b/lib/gitlab/git/commit.rb
index 2820491b65d..4f05c4b73a1 100644
--- a/lib/gitlab/git/commit.rb
+++ b/lib/gitlab/git/commit.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitlab::Git::Commit is a wrapper around Gitaly::GitCommit
 module Gitlab
   module Git
diff --git a/lib/gitlab/git/commit_stats.rb b/lib/gitlab/git/commit_stats.rb
index 83a9fd5f81a..8815088d23c 100644
--- a/lib/gitlab/git/commit_stats.rb
+++ b/lib/gitlab/git/commit_stats.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitlab::Git::CommitStats counts the additions, deletions, and total changes
 # in a commit.
 module Gitlab
diff --git a/lib/gitlab/git/compare.rb b/lib/gitlab/git/compare.rb
index 7cb842256d0..ab5245ba7cb 100644
--- a/lib/gitlab/git/compare.rb
+++ b/lib/gitlab/git/compare.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab
diff --git a/lib/gitlab/git/conflict/file.rb b/lib/gitlab/git/conflict/file.rb
index f08dab59ce4..7ffe4a7ae81 100644
--- a/lib/gitlab/git/conflict/file.rb
+++ b/lib/gitlab/git/conflict/file.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Conflict
diff --git a/lib/gitlab/git/conflict/parser.rb b/lib/gitlab/git/conflict/parser.rb
index fb5717dd556..20de8ebde4e 100644
--- a/lib/gitlab/git/conflict/parser.rb
+++ b/lib/gitlab/git/conflict/parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Conflict
diff --git a/lib/gitlab/git/conflict/resolution.rb b/lib/gitlab/git/conflict/resolution.rb
index ab9be683e15..04299a2d10c 100644
--- a/lib/gitlab/git/conflict/resolution.rb
+++ b/lib/gitlab/git/conflict/resolution.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Conflict
diff --git a/lib/gitlab/git/conflict/resolver.rb b/lib/gitlab/git/conflict/resolver.rb
index 307f1b8cb66..26e82643a4c 100644
--- a/lib/gitlab/git/conflict/resolver.rb
+++ b/lib/gitlab/git/conflict/resolver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Conflict
diff --git a/lib/gitlab/git/diff.rb b/lib/gitlab/git/diff.rb
index b2e2d49dd0b..74a4633424f 100644
--- a/lib/gitlab/git/diff.rb
+++ b/lib/gitlab/git/diff.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Diff
diff --git a/lib/gitlab/git/diff_collection.rb b/lib/gitlab/git/diff_collection.rb
index 47ebca7c4a2..5c70cb6c66c 100644
--- a/lib/gitlab/git/diff_collection.rb
+++ b/lib/gitlab/git/diff_collection.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab
diff --git a/lib/gitlab/git/gitmodules_parser.rb b/lib/gitlab/git/gitmodules_parser.rb
index 4b505312f60..575e12390cd 100644
--- a/lib/gitlab/git/gitmodules_parser.rb
+++ b/lib/gitlab/git/gitmodules_parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab
diff --git a/lib/gitlab/git/hook_env.rb b/lib/gitlab/git/hook_env.rb
index 620568d8817..892a069a3b7 100644
--- a/lib/gitlab/git/hook_env.rb
+++ b/lib/gitlab/git/hook_env.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab
diff --git a/lib/gitlab/git/index.rb b/lib/gitlab/git/index.rb
index c2e4274e3ee..3b9b516308f 100644
--- a/lib/gitlab/git/index.rb
+++ b/lib/gitlab/git/index.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Index
diff --git a/lib/gitlab/git/lfs_changes.rb b/lib/gitlab/git/lfs_changes.rb
index d7148165408..8e2a925dfea 100644
--- a/lib/gitlab/git/lfs_changes.rb
+++ b/lib/gitlab/git/lfs_changes.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class LfsChanges
diff --git a/lib/gitlab/git/lfs_pointer_file.rb b/lib/gitlab/git/lfs_pointer_file.rb
index 2ae0a889590..b7019a221ac 100644
--- a/lib/gitlab/git/lfs_pointer_file.rb
+++ b/lib/gitlab/git/lfs_pointer_file.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class LfsPointerFile
diff --git a/lib/gitlab/git/operation_service.rb b/lib/gitlab/git/operation_service.rb
index 0584629ac84..8797d3dce24 100644
--- a/lib/gitlab/git/operation_service.rb
+++ b/lib/gitlab/git/operation_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class OperationService
diff --git a/lib/gitlab/git/path_helper.rb b/lib/gitlab/git/path_helper.rb
index 57b82a37d6c..e3a2031eeca 100644
--- a/lib/gitlab/git/path_helper.rb
+++ b/lib/gitlab/git/path_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab
diff --git a/lib/gitlab/git/pre_receive_error.rb b/lib/gitlab/git/pre_receive_error.rb
index ac1ab7c39d5..03caace6fce 100644
--- a/lib/gitlab/git/pre_receive_error.rb
+++ b/lib/gitlab/git/pre_receive_error.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     #
diff --git a/lib/gitlab/git/raw_diff_change.rb b/lib/gitlab/git/raw_diff_change.rb
index 98de9328071..e1002af40f6 100644
--- a/lib/gitlab/git/raw_diff_change.rb
+++ b/lib/gitlab/git/raw_diff_change.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     # This class behaves like a struct with fields :blob_id, :blob_size, :operation, :old_path, :new_path
diff --git a/lib/gitlab/git/ref.rb b/lib/gitlab/git/ref.rb
index 31a280155bd..eec91194949 100644
--- a/lib/gitlab/git/ref.rb
+++ b/lib/gitlab/git/ref.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Ref
diff --git a/lib/gitlab/git/remote_mirror.rb b/lib/gitlab/git/remote_mirror.rb
index 7f9520de5ce..e992d522e7f 100644
--- a/lib/gitlab/git/remote_mirror.rb
+++ b/lib/gitlab/git/remote_mirror.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class RemoteMirror
diff --git a/lib/gitlab/git/remote_repository.rb b/lib/gitlab/git/remote_repository.rb
index f40e59a8dd0..234541d8145 100644
--- a/lib/gitlab/git/remote_repository.rb
+++ b/lib/gitlab/git/remote_repository.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     #
diff --git a/lib/gitlab/git/repository.rb b/lib/gitlab/git/repository.rb
index 1642c4c5687..716ad16fdf1 100644
--- a/lib/gitlab/git/repository.rb
+++ b/lib/gitlab/git/repository.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'tempfile'
 require 'forwardable'
 require "rubygems/package"
diff --git a/lib/gitlab/git/repository_mirroring.rb b/lib/gitlab/git/repository_mirroring.rb
index 752a91fbb60..7e63a6dc7cb 100644
--- a/lib/gitlab/git/repository_mirroring.rb
+++ b/lib/gitlab/git/repository_mirroring.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module RepositoryMirroring
diff --git a/lib/gitlab/git/tag.rb b/lib/gitlab/git/tag.rb
index bbf2ecdb1fa..ade708d0541 100644
--- a/lib/gitlab/git/tag.rb
+++ b/lib/gitlab/git/tag.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Tag < Ref
diff --git a/lib/gitlab/git/tree.rb b/lib/gitlab/git/tree.rb
index b5b701699f0..51542bcaaa2 100644
--- a/lib/gitlab/git/tree.rb
+++ b/lib/gitlab/git/tree.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Tree
diff --git a/lib/gitlab/git/user.rb b/lib/gitlab/git/user.rb
index 338e1a30c45..2c798844798 100644
--- a/lib/gitlab/git/user.rb
+++ b/lib/gitlab/git/user.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class User
diff --git a/lib/gitlab/git/util.rb b/lib/gitlab/git/util.rb
index 4708f22dcb3..03c2c1367b0 100644
--- a/lib/gitlab/git/util.rb
+++ b/lib/gitlab/git/util.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Gitaly note: JV: no RPC's here.
 
 module Gitlab
diff --git a/lib/gitlab/git/version.rb b/lib/gitlab/git/version.rb
index 4bd91898457..64c89656167 100644
--- a/lib/gitlab/git/version.rb
+++ b/lib/gitlab/git/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module Version
diff --git a/lib/gitlab/git/wiki.rb b/lib/gitlab/git/wiki.rb
index 02c643d0da0..c43331bed60 100644
--- a/lib/gitlab/git/wiki.rb
+++ b/lib/gitlab/git/wiki.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class Wiki
diff --git a/lib/gitlab/git/wiki_file.rb b/lib/gitlab/git/wiki_file.rb
index 64313bb04e8..c05a5adc00c 100644
--- a/lib/gitlab/git/wiki_file.rb
+++ b/lib/gitlab/git/wiki_file.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class WikiFile
diff --git a/lib/gitlab/git/wiki_page.rb b/lib/gitlab/git/wiki_page.rb
index c4087c9ebdc..f6cac398548 100644
--- a/lib/gitlab/git/wiki_page.rb
+++ b/lib/gitlab/git/wiki_page.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class WikiPage
diff --git a/lib/gitlab/git/wiki_page_version.rb b/lib/gitlab/git/wiki_page_version.rb
index d5e7e70fd31..475a9d4d1b9 100644
--- a/lib/gitlab/git/wiki_page_version.rb
+++ b/lib/gitlab/git/wiki_page_version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     class WikiPageVersion
diff --git a/lib/gitlab/git/wraps_gitaly_errors.rb b/lib/gitlab/git/wraps_gitaly_errors.rb
index 4b161f7e6ce..9963bcfbf1c 100644
--- a/lib/gitlab/git/wraps_gitaly_errors.rb
+++ b/lib/gitlab/git/wraps_gitaly_errors.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Git
     module WrapsGitalyErrors
diff --git a/lib/gitlab/gitaly_client/attributes_bag.rb b/lib/gitlab/gitaly_client/attributes_bag.rb
index 198a1de91c7..3f1a0ef4888 100644
--- a/lib/gitlab/gitaly_client/attributes_bag.rb
+++ b/lib/gitlab/gitaly_client/attributes_bag.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     # This module expects an `ATTRS` const to be defined on the subclass
diff --git a/lib/gitlab/gitaly_client/blob_service.rb b/lib/gitlab/gitaly_client/blob_service.rb
index 086ce31e678..39547328210 100644
--- a/lib/gitlab/gitaly_client/blob_service.rb
+++ b/lib/gitlab/gitaly_client/blob_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class BlobService
@@ -15,7 +17,7 @@ module Gitlab
         )
         response = GitalyClient.call(@gitaly_repo.storage_name, :blob_service, :get_blob, request, timeout: GitalyClient.fast_timeout)
 
-        data = ''
+        data = []
         blob = nil
         response.each do |msg|
           if blob.nil?
@@ -27,6 +29,8 @@ module Gitlab
 
         return nil if blob.oid.blank?
 
+        data = data.join
+
         Gitlab::Git::Blob.new(
           id: blob.oid,
           size: blob.size,
diff --git a/lib/gitlab/gitaly_client/blobs_stitcher.rb b/lib/gitlab/gitaly_client/blobs_stitcher.rb
index 5ca592ff812..01bab854082 100644
--- a/lib/gitlab/gitaly_client/blobs_stitcher.rb
+++ b/lib/gitlab/gitaly_client/blobs_stitcher.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class BlobsStitcher
diff --git a/lib/gitlab/gitaly_client/commit_service.rb b/lib/gitlab/gitaly_client/commit_service.rb
index 085b2a127a5..4e46cb9f05c 100644
--- a/lib/gitlab/gitaly_client/commit_service.rb
+++ b/lib/gitlab/gitaly_client/commit_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class CommitService
@@ -93,7 +95,7 @@ module Gitlab
         response = GitalyClient.call(@repository.storage, :commit_service, :tree_entry, request, timeout: GitalyClient.medium_timeout)
 
         entry = nil
-        data = ''
+        data = []
         response.each do |msg|
           if entry.nil?
             entry = msg
@@ -103,7 +105,7 @@ module Gitlab
 
           data << msg.data
         end
-        entry.data = data
+        entry.data = data.join
 
         entry unless entry.oid.blank?
       end
@@ -254,7 +256,7 @@ module Gitlab
         )
 
         response = GitalyClient.call(@repository.storage, :commit_service, :raw_blame, request, timeout: GitalyClient.medium_timeout)
-        response.reduce("") { |memo, msg| memo << msg.data }
+        response.reduce([]) { |memo, msg| memo << msg.data }.join
       end
 
       def find_commit(revision)
@@ -345,8 +347,8 @@ module Gitlab
         request = Gitaly::ExtractCommitSignatureRequest.new(repository: @gitaly_repo, commit_id: commit_id)
         response = GitalyClient.call(@repository.storage, :commit_service, :extract_commit_signature, request)
 
-        signature = ''.b
-        signed_text = ''.b
+        signature = +''.b
+        signed_text = +''.b
 
         response.each do |message|
           signature << message.signature
@@ -364,7 +366,7 @@ module Gitlab
         request = Gitaly::GetCommitSignaturesRequest.new(repository: @gitaly_repo, commit_ids: commit_ids)
         response = GitalyClient.call(@repository.storage, :commit_service, :get_commit_signatures, request, timeout: GitalyClient.fast_timeout)
 
-        signatures = Hash.new { |h, k| h[k] = [''.b, ''.b] }
+        signatures = Hash.new { |h, k| h[k] = [+''.b, +''.b] }
         current_commit_id = nil
 
         response.each do |message|
@@ -383,7 +385,7 @@ module Gitlab
         request = Gitaly::GetCommitMessagesRequest.new(repository: @gitaly_repo, commit_ids: commit_ids)
         response = GitalyClient.call(@repository.storage, :commit_service, :get_commit_messages, request, timeout: GitalyClient.fast_timeout)
 
-        messages = Hash.new { |h, k| h[k] = ''.b }
+        messages = Hash.new { |h, k| h[k] = +''.b }
         current_commit_id = nil
 
         response.each do |rpc_message|
diff --git a/lib/gitlab/gitaly_client/conflict_files_stitcher.rb b/lib/gitlab/gitaly_client/conflict_files_stitcher.rb
index c275a065bce..0e00f6e8c44 100644
--- a/lib/gitlab/gitaly_client/conflict_files_stitcher.rb
+++ b/lib/gitlab/gitaly_client/conflict_files_stitcher.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class ConflictFilesStitcher
@@ -17,7 +19,7 @@ module Gitlab
 
               current_file = file_from_gitaly_header(gitaly_file.header)
             else
-              current_file.raw_content << gitaly_file.content
+              current_file.raw_content = "#{current_file.raw_content}#{gitaly_file.content}"
             end
           end
         end
diff --git a/lib/gitlab/gitaly_client/conflicts_service.rb b/lib/gitlab/gitaly_client/conflicts_service.rb
index aa7e03301f5..6304f998563 100644
--- a/lib/gitlab/gitaly_client/conflicts_service.rb
+++ b/lib/gitlab/gitaly_client/conflicts_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class ConflictsService
diff --git a/lib/gitlab/gitaly_client/diff.rb b/lib/gitlab/gitaly_client/diff.rb
index af9d674535b..dd192ccde1a 100644
--- a/lib/gitlab/gitaly_client/diff.rb
+++ b/lib/gitlab/gitaly_client/diff.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class Diff
diff --git a/lib/gitlab/gitaly_client/diff_stitcher.rb b/lib/gitlab/gitaly_client/diff_stitcher.rb
index da243ee2d1a..98d327a7329 100644
--- a/lib/gitlab/gitaly_client/diff_stitcher.rb
+++ b/lib/gitlab/gitaly_client/diff_stitcher.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class DiffStitcher
@@ -20,7 +22,7 @@ module Gitlab
 
             current_diff = GitalyClient::Diff.new(diff_params)
           else
-            current_diff.patch += diff_msg.raw_patch_data
+            current_diff.patch = "#{current_diff.patch}#{diff_msg.raw_patch_data}"
           end
 
           if diff_msg.end_of_patch
diff --git a/lib/gitlab/gitaly_client/health_check_service.rb b/lib/gitlab/gitaly_client/health_check_service.rb
index 6c1213f5e20..0c495f60633 100644
--- a/lib/gitlab/gitaly_client/health_check_service.rb
+++ b/lib/gitlab/gitaly_client/health_check_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class HealthCheckService
diff --git a/lib/gitlab/gitaly_client/namespace_service.rb b/lib/gitlab/gitaly_client/namespace_service.rb
index d4e982b649a..f0be3cbebd2 100644
--- a/lib/gitlab/gitaly_client/namespace_service.rb
+++ b/lib/gitlab/gitaly_client/namespace_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class NamespaceService
diff --git a/lib/gitlab/gitaly_client/notification_service.rb b/lib/gitlab/gitaly_client/notification_service.rb
index 326e6f7dafc..873c3e4086d 100644
--- a/lib/gitlab/gitaly_client/notification_service.rb
+++ b/lib/gitlab/gitaly_client/notification_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class NotificationService
diff --git a/lib/gitlab/gitaly_client/operation_service.rb b/lib/gitlab/gitaly_client/operation_service.rb
index 4c78b790ce5..c32c2c0b2fb 100644
--- a/lib/gitlab/gitaly_client/operation_service.rb
+++ b/lib/gitlab/gitaly_client/operation_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class OperationService
diff --git a/lib/gitlab/gitaly_client/queue_enumerator.rb b/lib/gitlab/gitaly_client/queue_enumerator.rb
index b8018029552..3a412102abe 100644
--- a/lib/gitlab/gitaly_client/queue_enumerator.rb
+++ b/lib/gitlab/gitaly_client/queue_enumerator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class QueueEnumerator
diff --git a/lib/gitlab/gitaly_client/ref_service.rb b/lib/gitlab/gitaly_client/ref_service.rb
index 8acc22e809e..d5633d167ac 100644
--- a/lib/gitlab/gitaly_client/ref_service.rb
+++ b/lib/gitlab/gitaly_client/ref_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class RefService
@@ -218,7 +220,7 @@ module Gitlab
         request = Gitaly::GetTagMessagesRequest.new(repository: @gitaly_repo, tag_ids: tag_ids)
         response = GitalyClient.call(@repository.storage, :ref_service, :get_tag_messages, request, timeout: GitalyClient.fast_timeout)
 
-        messages = Hash.new { |h, k| h[k] = ''.b }
+        messages = Hash.new { |h, k| h[k] = +''.b }
         current_tag_id = nil
 
         response.each do |rpc_message|
diff --git a/lib/gitlab/gitaly_client/remote_service.rb b/lib/gitlab/gitaly_client/remote_service.rb
index 4661448621b..24e8a5e16d3 100644
--- a/lib/gitlab/gitaly_client/remote_service.rb
+++ b/lib/gitlab/gitaly_client/remote_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class RemoteService
diff --git a/lib/gitlab/gitaly_client/repository_service.rb b/lib/gitlab/gitaly_client/repository_service.rb
index d7b36946b65..f968ebc2cbf 100644
--- a/lib/gitlab/gitaly_client/repository_service.rb
+++ b/lib/gitlab/gitaly_client/repository_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class RepositoryService
@@ -56,9 +58,9 @@ module Gitlab
         request = Gitaly::GetInfoAttributesRequest.new(repository: @gitaly_repo)
 
         response = GitalyClient.call(@storage, :repository_service, :get_info_attributes, request, timeout: GitalyClient.fast_timeout)
-        response.each_with_object("") do |message, attributes|
+        response.each_with_object([]) do |message, attributes|
           attributes << message.attributes
-        end
+        end.join
       end
 
       def fetch_remote(remote, ssh_auth:, forced:, no_tags:, timeout:, prune: true)
diff --git a/lib/gitlab/gitaly_client/server_service.rb b/lib/gitlab/gitaly_client/server_service.rb
index ad898278353..0ade6942db9 100644
--- a/lib/gitlab/gitaly_client/server_service.rb
+++ b/lib/gitlab/gitaly_client/server_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     # Meant for extraction of server data, and later maybe to perform misc task
diff --git a/lib/gitlab/gitaly_client/storage_service.rb b/lib/gitlab/gitaly_client/storage_service.rb
index 3a26dd58ff4..4edcb0b8ba9 100644
--- a/lib/gitlab/gitaly_client/storage_service.rb
+++ b/lib/gitlab/gitaly_client/storage_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class StorageService
diff --git a/lib/gitlab/gitaly_client/storage_settings.rb b/lib/gitlab/gitaly_client/storage_settings.rb
index 26d1f53f26c..754cccb6b3f 100644
--- a/lib/gitlab/gitaly_client/storage_settings.rb
+++ b/lib/gitlab/gitaly_client/storage_settings.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     # This is a chokepoint that is meant to help us stop remove all places
diff --git a/lib/gitlab/gitaly_client/util.rb b/lib/gitlab/gitaly_client/util.rb
index 9c19c51d412..dce5d6a8ad0 100644
--- a/lib/gitlab/gitaly_client/util.rb
+++ b/lib/gitlab/gitaly_client/util.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     module Util
diff --git a/lib/gitlab/gitaly_client/wiki_file.rb b/lib/gitlab/gitaly_client/wiki_file.rb
index 47c60c92484..ef2b23732d1 100644
--- a/lib/gitlab/gitaly_client/wiki_file.rb
+++ b/lib/gitlab/gitaly_client/wiki_file.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class WikiFile
diff --git a/lib/gitlab/gitaly_client/wiki_page.rb b/lib/gitlab/gitaly_client/wiki_page.rb
index a02d15db5dd..757a429fb8a 100644
--- a/lib/gitlab/gitaly_client/wiki_page.rb
+++ b/lib/gitlab/gitaly_client/wiki_page.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitalyClient
     class WikiPage
diff --git a/lib/gitlab/gitaly_client/wiki_service.rb b/lib/gitlab/gitaly_client/wiki_service.rb
index 7c2c228ad01..2b3d622af4d 100644
--- a/lib/gitlab/gitaly_client/wiki_service.rb
+++ b/lib/gitlab/gitaly_client/wiki_service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'stringio'
 
 module Gitlab
@@ -139,7 +141,7 @@ module Gitlab
           next unless message.name.present? || wiki_file
 
           if wiki_file
-            wiki_file.raw_data << message.raw_data
+            wiki_file.raw_data = "#{wiki_file.raw_data}#{message.raw_data}"
           else
             wiki_file = GitalyClient::WikiFile.new(message.to_h)
             # All gRPC strings in a response are frozen, so we get
@@ -160,7 +162,7 @@ module Gitlab
         )
 
         response = GitalyClient.call(@repository.storage, :wiki_service, :wiki_get_formatted_data, request)
-        response.reduce("") { |memo, msg| memo << msg.data }
+        response.reduce([]) { |memo, msg| memo << msg.data }.join
       end
 
       private
diff --git a/lib/gitlab/gitlab_import/client.rb b/lib/gitlab/gitlab_import/client.rb
index 38ef12491df..86474159f8b 100644
--- a/lib/gitlab/gitlab_import/client.rb
+++ b/lib/gitlab/gitlab_import/client.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitlabImport
     class Client
diff --git a/lib/gitlab/gitlab_import/importer.rb b/lib/gitlab/gitlab_import/importer.rb
index 047487f1d24..e84863deba8 100644
--- a/lib/gitlab/gitlab_import/importer.rb
+++ b/lib/gitlab/gitlab_import/importer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitlabImport
     class Importer
@@ -22,22 +24,22 @@ module Gitlab
           issues = client.issues(project_identifier)
 
           issues.each do |issue|
-            body = @formatter.author_line(issue["author"]["name"])
-            body += issue["description"]
+            body = [@formatter.author_line(issue["author"]["name"])]
+            body << issue["description"]
 
             comments = client.issue_comments(project_identifier, issue["iid"])
 
             if comments.any?
-              body += @formatter.comments_header
+              body << @formatter.comments_header
             end
 
             comments.each do |comment|
-              body += @formatter.comment(comment["author"]["name"], comment["created_at"], comment["body"])
+              body << @formatter.comment(comment["author"]["name"], comment["created_at"], comment["body"])
             end
 
             project.issues.create!(
               iid: issue["iid"],
-              description: body,
+              description: body.join,
               title: issue["title"],
               state: issue["state"],
               updated_at: issue["updated_at"],
diff --git a/lib/gitlab/gitlab_import/project_creator.rb b/lib/gitlab/gitlab_import/project_creator.rb
index 430b8c10058..35feea17351 100644
--- a/lib/gitlab/gitlab_import/project_creator.rb
+++ b/lib/gitlab/gitlab_import/project_creator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GitlabImport
     class ProjectCreator
diff --git a/lib/gitlab/google_code_import/client.rb b/lib/gitlab/google_code_import/client.rb
index b1dbf554e41..52d714880b5 100644
--- a/lib/gitlab/google_code_import/client.rb
+++ b/lib/gitlab/google_code_import/client.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GoogleCodeImport
     class Client
diff --git a/lib/gitlab/google_code_import/importer.rb b/lib/gitlab/google_code_import/importer.rb
index 0c08c0fedaa..1e7203cb82a 100644
--- a/lib/gitlab/google_code_import/importer.rb
+++ b/lib/gitlab/google_code_import/importer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GoogleCodeImport
     class Importer
diff --git a/lib/gitlab/google_code_import/project_creator.rb b/lib/gitlab/google_code_import/project_creator.rb
index 326cfcaa8af..eaef85acb98 100644
--- a/lib/gitlab/google_code_import/project_creator.rb
+++ b/lib/gitlab/google_code_import/project_creator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GoogleCodeImport
     class ProjectCreator
diff --git a/lib/gitlab/google_code_import/repository.rb b/lib/gitlab/google_code_import/repository.rb
index ad33fc2cad2..19627c8cd35 100644
--- a/lib/gitlab/google_code_import/repository.rb
+++ b/lib/gitlab/google_code_import/repository.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GoogleCodeImport
     class Repository
diff --git a/lib/gitlab/gpg/commit.rb b/lib/gitlab/gpg/commit.rb
index 2bc081a6181..31bab20b044 100644
--- a/lib/gitlab/gpg/commit.rb
+++ b/lib/gitlab/gpg/commit.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Gpg
     class Commit
diff --git a/lib/gitlab/gpg/invalid_gpg_signature_updater.rb b/lib/gitlab/gpg/invalid_gpg_signature_updater.rb
index 6972bd685f7..d892d27a917 100644
--- a/lib/gitlab/gpg/invalid_gpg_signature_updater.rb
+++ b/lib/gitlab/gpg/invalid_gpg_signature_updater.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Gpg
     class InvalidGpgSignatureUpdater
diff --git a/lib/gitlab/grape_logging/formatters/lograge_with_timestamp.rb b/lib/gitlab/grape_logging/formatters/lograge_with_timestamp.rb
index 41004408dec..9bb1e8fc7a2 100644
--- a/lib/gitlab/grape_logging/formatters/lograge_with_timestamp.rb
+++ b/lib/gitlab/grape_logging/formatters/lograge_with_timestamp.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module GrapeLogging
     module Formatters
diff --git a/lib/gitlab/grape_logging/loggers/queue_duration_logger.rb b/lib/gitlab/grape_logging/loggers/queue_duration_logger.rb
index 0adac79f25a..705e23adff2 100644
--- a/lib/gitlab/grape_logging/loggers/queue_duration_logger.rb
+++ b/lib/gitlab/grape_logging/loggers/queue_duration_logger.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This grape_logging module (https://github.com/aserafin/grape_logging) makes it
 # possible to log how much time an API request was queued by Workhorse.
 module Gitlab
diff --git a/lib/gitlab/grape_logging/loggers/user_logger.rb b/lib/gitlab/grape_logging/loggers/user_logger.rb
index fa172861967..6caa6c715e7 100644
--- a/lib/gitlab/grape_logging/loggers/user_logger.rb
+++ b/lib/gitlab/grape_logging/loggers/user_logger.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This grape_logging module (https://github.com/aserafin/grape_logging) makes it
 # possible to log the user who performed the Grape API action by retrieving
 # the user context from the request environment.
diff --git a/lib/gitlab/graphql/authorize.rb b/lib/gitlab/graphql/authorize.rb
index 93a903915b0..5e48bf9043d 100644
--- a/lib/gitlab/graphql/authorize.rb
+++ b/lib/gitlab/graphql/authorize.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     # Allow fields to declare permissions their objects must have. The field
diff --git a/lib/gitlab/graphql/authorize/authorize_resource.rb b/lib/gitlab/graphql/authorize/authorize_resource.rb
index 40895686a8a..a56c4f6368d 100644
--- a/lib/gitlab/graphql/authorize/authorize_resource.rb
+++ b/lib/gitlab/graphql/authorize/authorize_resource.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Authorize
diff --git a/lib/gitlab/graphql/authorize/instrumentation.rb b/lib/gitlab/graphql/authorize/instrumentation.rb
index 6cb8e617f62..d638d2b43ee 100644
--- a/lib/gitlab/graphql/authorize/instrumentation.rb
+++ b/lib/gitlab/graphql/authorize/instrumentation.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Authorize
diff --git a/lib/gitlab/graphql/connections.rb b/lib/gitlab/graphql/connections.rb
index 2582ffeb2a8..fbccdfa7b08 100644
--- a/lib/gitlab/graphql/connections.rb
+++ b/lib/gitlab/graphql/connections.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Connections
diff --git a/lib/gitlab/graphql/connections/keyset_connection.rb b/lib/gitlab/graphql/connections/keyset_connection.rb
index 3c0d7e9784a..851054c0393 100644
--- a/lib/gitlab/graphql/connections/keyset_connection.rb
+++ b/lib/gitlab/graphql/connections/keyset_connection.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Connections
diff --git a/lib/gitlab/graphql/errors.rb b/lib/gitlab/graphql/errors.rb
index f8c7ec24be1..fe74549e322 100644
--- a/lib/gitlab/graphql/errors.rb
+++ b/lib/gitlab/graphql/errors.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Errors
diff --git a/lib/gitlab/graphql/expose_permissions.rb b/lib/gitlab/graphql/expose_permissions.rb
index e3779995406..365b7cca24f 100644
--- a/lib/gitlab/graphql/expose_permissions.rb
+++ b/lib/gitlab/graphql/expose_permissions.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module ExposePermissions
diff --git a/lib/gitlab/graphql/present.rb b/lib/gitlab/graphql/present.rb
index 2c7b64f1be9..7f69bf601d6 100644
--- a/lib/gitlab/graphql/present.rb
+++ b/lib/gitlab/graphql/present.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Present
diff --git a/lib/gitlab/graphql/present/instrumentation.rb b/lib/gitlab/graphql/present/instrumentation.rb
index f87fd147b15..ab03c40c22d 100644
--- a/lib/gitlab/graphql/present/instrumentation.rb
+++ b/lib/gitlab/graphql/present/instrumentation.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     module Present
diff --git a/lib/gitlab/graphql/variables.rb b/lib/gitlab/graphql/variables.rb
index ffbaf65b512..b13ea37c21f 100644
--- a/lib/gitlab/graphql/variables.rb
+++ b/lib/gitlab/graphql/variables.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphql
     class Variables
diff --git a/lib/gitlab/graphs/commits.rb b/lib/gitlab/graphs/commits.rb
index c4ffc19df09..66e1b2e78b4 100644
--- a/lib/gitlab/graphs/commits.rb
+++ b/lib/gitlab/graphs/commits.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Graphs
     class Commits
diff --git a/lib/gitlab/hashed_storage/migrator.rb b/lib/gitlab/hashed_storage/migrator.rb
index 4edc251facb..1f29cf10cad 100644
--- a/lib/gitlab/hashed_storage/migrator.rb
+++ b/lib/gitlab/hashed_storage/migrator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HashedStorage
     # Hashed Storage Migrator
diff --git a/lib/gitlab/hashed_storage/rake_helper.rb b/lib/gitlab/hashed_storage/rake_helper.rb
index 22edd5f999d..38f552fab03 100644
--- a/lib/gitlab/hashed_storage/rake_helper.rb
+++ b/lib/gitlab/hashed_storage/rake_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HashedStorage
     module RakeHelper
diff --git a/lib/gitlab/health_checks/base_abstract_check.rb b/lib/gitlab/health_checks/base_abstract_check.rb
index 8b365dab185..1d31f59999c 100644
--- a/lib/gitlab/health_checks/base_abstract_check.rb
+++ b/lib/gitlab/health_checks/base_abstract_check.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module BaseAbstractCheck
diff --git a/lib/gitlab/health_checks/db_check.rb b/lib/gitlab/health_checks/db_check.rb
index 08495c0a59e..2bcd25cd3cc 100644
--- a/lib/gitlab/health_checks/db_check.rb
+++ b/lib/gitlab/health_checks/db_check.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     class DbCheck
diff --git a/lib/gitlab/health_checks/gitaly_check.rb b/lib/gitlab/health_checks/gitaly_check.rb
index 1f623e0b6ec..898733fea5d 100644
--- a/lib/gitlab/health_checks/gitaly_check.rb
+++ b/lib/gitlab/health_checks/gitaly_check.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     class GitalyCheck
diff --git a/lib/gitlab/health_checks/metric.rb b/lib/gitlab/health_checks/metric.rb
index d62d9136886..62a5216d159 100644
--- a/lib/gitlab/health_checks/metric.rb
+++ b/lib/gitlab/health_checks/metric.rb
@@ -1,3 +1,6 @@
-module Gitlab::HealthChecks # rubocop:disable Naming/FileName
+# rubocop:disable Naming/FileName
+# frozen_string_literal: true
+
+module Gitlab::HealthChecks
   Metric = Struct.new(:name, :value, :labels)
 end
diff --git a/lib/gitlab/health_checks/prometheus_text_format.rb b/lib/gitlab/health_checks/prometheus_text_format.rb
index b3c759b4730..2a8f9d31cd5 100644
--- a/lib/gitlab/health_checks/prometheus_text_format.rb
+++ b/lib/gitlab/health_checks/prometheus_text_format.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     class PrometheusTextFormat
diff --git a/lib/gitlab/health_checks/redis/cache_check.rb b/lib/gitlab/health_checks/redis/cache_check.rb
index 2f6c4db12bb..0c8fe83893b 100644
--- a/lib/gitlab/health_checks/redis/cache_check.rb
+++ b/lib/gitlab/health_checks/redis/cache_check.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module Redis
diff --git a/lib/gitlab/health_checks/redis/queues_check.rb b/lib/gitlab/health_checks/redis/queues_check.rb
index 63d2882c5b2..b1e33b9f459 100644
--- a/lib/gitlab/health_checks/redis/queues_check.rb
+++ b/lib/gitlab/health_checks/redis/queues_check.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module Redis
diff --git a/lib/gitlab/health_checks/redis/redis_check.rb b/lib/gitlab/health_checks/redis/redis_check.rb
index 8ceb0a0aa46..f7e46fce134 100644
--- a/lib/gitlab/health_checks/redis/redis_check.rb
+++ b/lib/gitlab/health_checks/redis/redis_check.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module Redis
diff --git a/lib/gitlab/health_checks/redis/shared_state_check.rb b/lib/gitlab/health_checks/redis/shared_state_check.rb
index f1ea1ffe1be..285ac271929 100644
--- a/lib/gitlab/health_checks/redis/shared_state_check.rb
+++ b/lib/gitlab/health_checks/redis/shared_state_check.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module Redis
diff --git a/lib/gitlab/health_checks/result.rb b/lib/gitlab/health_checks/result.rb
index e323e2c9723..d32a6980eb8 100644
--- a/lib/gitlab/health_checks/result.rb
+++ b/lib/gitlab/health_checks/result.rb
@@ -1,3 +1,6 @@
-module Gitlab::HealthChecks # rubocop:disable Naming/FileName
+# rubocop:disable Naming/FileName
+# frozen_string_literal: true
+
+module Gitlab::HealthChecks
   Result = Struct.new(:success, :message, :labels)
 end
diff --git a/lib/gitlab/health_checks/simple_abstract_check.rb b/lib/gitlab/health_checks/simple_abstract_check.rb
index 96945ce5b20..3588260d6eb 100644
--- a/lib/gitlab/health_checks/simple_abstract_check.rb
+++ b/lib/gitlab/health_checks/simple_abstract_check.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module HealthChecks
     module SimpleAbstractCheck