Enable frozen string for lib/gitlab/ci

Enables frozen string for the following:

* lib/gitlab/ci/*.rb
* lib/gitlab/ci/build/**/*.rb
* lib/gitlab/ci/config/**/*.rb
* lib/gitlab/ci/pipeline/**/*.rb
* lib/gitlab/ci/reports/**/*.rb

Partially addresses #47424.

90 files changed, 188 insertions, 2 deletions

diff --git a/changelogs/unreleased/frozen-string-enable-lib-gitlab-ci.yml b/changelogs/unreleased/frozen-string-enable-lib-gitlab-ci.yml
new file mode 100644
index 00000000000..a881c304f34
--- /dev/null
+++ b/changelogs/unreleased/frozen-string-enable-lib-gitlab-ci.yml
@@ -0,0 +1,5 @@
+---
+title: Enable frozen string for lib/gitlab/ci
+merge_request:
+author: gfyoung
+type: performance
diff --git a/lib/gitlab/ci/ansi2html.rb b/lib/gitlab/ci/ansi2html.rb
index e780f8c646b..974b5ad6877 100644
--- a/lib/gitlab/ci/ansi2html.rb
+++ b/lib/gitlab/ci/ansi2html.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # ANSI color library
 #
 # Implementation per http://en.wikipedia.org/wiki/ANSI_escape_code
@@ -265,7 +267,7 @@ module Gitlab
         def reset_state
           @offset = 0
           @n_open_tags = 0
-          @out = ''
+          @out = +''
           reset
         end
 
diff --git a/lib/gitlab/ci/build/artifacts/adapters/gzip_stream.rb b/lib/gitlab/ci/build/artifacts/adapters/gzip_stream.rb
index ee3647f24fd..25a82086676 100644
--- a/lib/gitlab/ci/build/artifacts/adapters/gzip_stream.rb
+++ b/lib/gitlab/ci/build/artifacts/adapters/gzip_stream.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/artifacts/adapters/raw_stream.rb b/lib/gitlab/ci/build/artifacts/adapters/raw_stream.rb
index fa6842cf36a..cf37d700991 100644
--- a/lib/gitlab/ci/build/artifacts/adapters/raw_stream.rb
+++ b/lib/gitlab/ci/build/artifacts/adapters/raw_stream.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/artifacts/metadata.rb b/lib/gitlab/ci/build/artifacts/metadata.rb
index 551d4f4473e..08dac756cc1 100644
--- a/lib/gitlab/ci/build/artifacts/metadata.rb
+++ b/lib/gitlab/ci/build/artifacts/metadata.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'zlib'
 require 'json'
 
diff --git a/lib/gitlab/ci/build/artifacts/metadata/entry.rb b/lib/gitlab/ci/build/artifacts/metadata/entry.rb
index 85072a072d6..d0a80518ae8 100644
--- a/lib/gitlab/ci/build/artifacts/metadata/entry.rb
+++ b/lib/gitlab/ci/build/artifacts/metadata/entry.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/artifacts/path.rb b/lib/gitlab/ci/build/artifacts/path.rb
index 9cd9b36c5f8..65cd935afaa 100644
--- a/lib/gitlab/ci/build/artifacts/path.rb
+++ b/lib/gitlab/ci/build/artifacts/path.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/credentials/base.rb b/lib/gitlab/ci/build/credentials/base.rb
index 29a7a27c963..58adf6e506d 100644
--- a/lib/gitlab/ci/build/credentials/base.rb
+++ b/lib/gitlab/ci/build/credentials/base.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/credentials/factory.rb b/lib/gitlab/ci/build/credentials/factory.rb
index 2423aa8857d..fa805abb8bb 100644
--- a/lib/gitlab/ci/build/credentials/factory.rb
+++ b/lib/gitlab/ci/build/credentials/factory.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/credentials/registry.rb b/lib/gitlab/ci/build/credentials/registry.rb
index 55eafcaed10..1c8588d9913 100644
--- a/lib/gitlab/ci/build/credentials/registry.rb
+++ b/lib/gitlab/ci/build/credentials/registry.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/image.rb b/lib/gitlab/ci/build/image.rb
index c811f88f483..4dd932f61d4 100644
--- a/lib/gitlab/ci/build/image.rb
+++ b/lib/gitlab/ci/build/image.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/policy.rb b/lib/gitlab/ci/build/policy.rb
index d10cc7802d4..43c46ad74af 100644
--- a/lib/gitlab/ci/build/policy.rb
+++ b/lib/gitlab/ci/build/policy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/policy/kubernetes.rb b/lib/gitlab/ci/build/policy/kubernetes.rb
index 782f6c4c0af..4c7dc947cd0 100644
--- a/lib/gitlab/ci/build/policy/kubernetes.rb
+++ b/lib/gitlab/ci/build/policy/kubernetes.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/policy/refs.rb b/lib/gitlab/ci/build/policy/refs.rb
index 4aa5dc89f47..10934536536 100644
--- a/lib/gitlab/ci/build/policy/refs.rb
+++ b/lib/gitlab/ci/build/policy/refs.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/policy/specification.rb b/lib/gitlab/ci/build/policy/specification.rb
index f09ba42c074..ceb5210cfb5 100644
--- a/lib/gitlab/ci/build/policy/specification.rb
+++ b/lib/gitlab/ci/build/policy/specification.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/policy/variables.rb b/lib/gitlab/ci/build/policy/variables.rb
index 9d2a362b7d4..0698136166a 100644
--- a/lib/gitlab/ci/build/policy/variables.rb
+++ b/lib/gitlab/ci/build/policy/variables.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/build/step.rb b/lib/gitlab/ci/build/step.rb
index 0b1ebe4e048..d587c896712 100644
--- a/lib/gitlab/ci/build/step.rb
+++ b/lib/gitlab/ci/build/step.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Build
diff --git a/lib/gitlab/ci/charts.rb b/lib/gitlab/ci/charts.rb
index 7b7354bce16..a4f01468e8e 100644
--- a/lib/gitlab/ci/charts.rb
+++ b/lib/gitlab/ci/charts.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Charts
diff --git a/lib/gitlab/ci/config.rb b/lib/gitlab/ci/config.rb
index fedaf18ef30..2fb3c4582e7 100644
--- a/lib/gitlab/ci/config.rb
+++ b/lib/gitlab/ci/config.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     #
diff --git a/lib/gitlab/ci/config/entry/artifacts.rb b/lib/gitlab/ci/config/entry/artifacts.rb
index e80f9d2e452..ef5f25b42c0 100644
--- a/lib/gitlab/ci/config/entry/artifacts.rb
+++ b/lib/gitlab/ci/config/entry/artifacts.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/attributable.rb b/lib/gitlab/ci/config/entry/attributable.rb
index 3e87a09704e..3c2e1df9b83 100644
--- a/lib/gitlab/ci/config/entry/attributable.rb
+++ b/lib/gitlab/ci/config/entry/attributable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/boolean.rb b/lib/gitlab/ci/config/entry/boolean.rb
index f3357f85b99..b9639c83075 100644
--- a/lib/gitlab/ci/config/entry/boolean.rb
+++ b/lib/gitlab/ci/config/entry/boolean.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/cache.rb b/lib/gitlab/ci/config/entry/cache.rb
index d7e09acbbf3..0a25057f482 100644
--- a/lib/gitlab/ci/config/entry/cache.rb
+++ b/lib/gitlab/ci/config/entry/cache.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/commands.rb b/lib/gitlab/ci/config/entry/commands.rb
index 9f66f11be9b..d9658291ebe 100644
--- a/lib/gitlab/ci/config/entry/commands.rb
+++ b/lib/gitlab/ci/config/entry/commands.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/configurable.rb b/lib/gitlab/ci/config/entry/configurable.rb
index 697f622c45e..4aabf0cfa31 100644
--- a/lib/gitlab/ci/config/entry/configurable.rb
+++ b/lib/gitlab/ci/config/entry/configurable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/coverage.rb b/lib/gitlab/ci/config/entry/coverage.rb
index 12a063059cb..690409ccf77 100644
--- a/lib/gitlab/ci/config/entry/coverage.rb
+++ b/lib/gitlab/ci/config/entry/coverage.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/environment.rb b/lib/gitlab/ci/config/entry/environment.rb
index 0c1f9eb7cbf..07e9e1d3f67 100644
--- a/lib/gitlab/ci/config/entry/environment.rb
+++ b/lib/gitlab/ci/config/entry/environment.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/factory.rb b/lib/gitlab/ci/config/entry/factory.rb
index 6be8288748f..85c9c3511a4 100644
--- a/lib/gitlab/ci/config/entry/factory.rb
+++ b/lib/gitlab/ci/config/entry/factory.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/global.rb b/lib/gitlab/ci/config/entry/global.rb
index 04077fa7a61..eba203d9d06 100644
--- a/lib/gitlab/ci/config/entry/global.rb
+++ b/lib/gitlab/ci/config/entry/global.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/hidden.rb b/lib/gitlab/ci/config/entry/hidden.rb
index 6fc3aa385bc..dc0ede2a25f 100644
--- a/lib/gitlab/ci/config/entry/hidden.rb
+++ b/lib/gitlab/ci/config/entry/hidden.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/image.rb b/lib/gitlab/ci/config/entry/image.rb
index 2844be80a84..fc453b72fa5 100644
--- a/lib/gitlab/ci/config/entry/image.rb
+++ b/lib/gitlab/ci/config/entry/image.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/job.rb b/lib/gitlab/ci/config/entry/job.rb
index f290ff3a565..e4610faa327 100644
--- a/lib/gitlab/ci/config/entry/job.rb
+++ b/lib/gitlab/ci/config/entry/job.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/jobs.rb b/lib/gitlab/ci/config/entry/jobs.rb
index 96b6f2e5d6c..1535b108000 100644
--- a/lib/gitlab/ci/config/entry/jobs.rb
+++ b/lib/gitlab/ci/config/entry/jobs.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/key.rb b/lib/gitlab/ci/config/entry/key.rb
index f27ad0a7759..963b200c7bb 100644
--- a/lib/gitlab/ci/config/entry/key.rb
+++ b/lib/gitlab/ci/config/entry/key.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/legacy_validation_helpers.rb b/lib/gitlab/ci/config/entry/legacy_validation_helpers.rb
index a3d4432be82..4043629dea9 100644
--- a/lib/gitlab/ci/config/entry/legacy_validation_helpers.rb
+++ b/lib/gitlab/ci/config/entry/legacy_validation_helpers.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/node.rb b/lib/gitlab/ci/config/entry/node.rb
index 26505c91be3..347089722e4 100644
--- a/lib/gitlab/ci/config/entry/node.rb
+++ b/lib/gitlab/ci/config/entry/node.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/paths.rb b/lib/gitlab/ci/config/entry/paths.rb
index 68dad161149..9580b5e2e7f 100644
--- a/lib/gitlab/ci/config/entry/paths.rb
+++ b/lib/gitlab/ci/config/entry/paths.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/policy.rb b/lib/gitlab/ci/config/entry/policy.rb
index c92562f8c85..0535d7c1a1a 100644
--- a/lib/gitlab/ci/config/entry/policy.rb
+++ b/lib/gitlab/ci/config/entry/policy.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/script.rb b/lib/gitlab/ci/config/entry/script.rb
index 29ecd9995ca..f7d39e5cf55 100644
--- a/lib/gitlab/ci/config/entry/script.rb
+++ b/lib/gitlab/ci/config/entry/script.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/service.rb b/lib/gitlab/ci/config/entry/service.rb
index 3e2ebcff31a..47bf9205147 100644
--- a/lib/gitlab/ci/config/entry/service.rb
+++ b/lib/gitlab/ci/config/entry/service.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/services.rb b/lib/gitlab/ci/config/entry/services.rb
index 0066894e069..bdf7f80f382 100644
--- a/lib/gitlab/ci/config/entry/services.rb
+++ b/lib/gitlab/ci/config/entry/services.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/simplifiable.rb b/lib/gitlab/ci/config/entry/simplifiable.rb
index 12764629686..9961bbfaa40 100644
--- a/lib/gitlab/ci/config/entry/simplifiable.rb
+++ b/lib/gitlab/ci/config/entry/simplifiable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/stage.rb b/lib/gitlab/ci/config/entry/stage.rb
index b7afaba1de8..65ab5953131 100644
--- a/lib/gitlab/ci/config/entry/stage.rb
+++ b/lib/gitlab/ci/config/entry/stage.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/stages.rb b/lib/gitlab/ci/config/entry/stages.rb
index ec187bd3732..ab184246d29 100644
--- a/lib/gitlab/ci/config/entry/stages.rb
+++ b/lib/gitlab/ci/config/entry/stages.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/undefined.rb b/lib/gitlab/ci/config/entry/undefined.rb
index 1171ac10f22..77dcfa88170 100644
--- a/lib/gitlab/ci/config/entry/undefined.rb
+++ b/lib/gitlab/ci/config/entry/undefined.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/unspecified.rb b/lib/gitlab/ci/config/entry/unspecified.rb
index fbb2551e870..bab32489d2f 100644
--- a/lib/gitlab/ci/config/entry/unspecified.rb
+++ b/lib/gitlab/ci/config/entry/unspecified.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/validatable.rb b/lib/gitlab/ci/config/entry/validatable.rb
index e45787773a8..08a6593c980 100644
--- a/lib/gitlab/ci/config/entry/validatable.rb
+++ b/lib/gitlab/ci/config/entry/validatable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/validator.rb b/lib/gitlab/ci/config/entry/validator.rb
index 2df23a3edcd..33ffdd3a95d 100644
--- a/lib/gitlab/ci/config/entry/validator.rb
+++ b/lib/gitlab/ci/config/entry/validator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/validators.rb b/lib/gitlab/ci/config/entry/validators.rb
index f6b4ba7843e..805d26ca8d8 100644
--- a/lib/gitlab/ci/config/entry/validators.rb
+++ b/lib/gitlab/ci/config/entry/validators.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/entry/variables.rb b/lib/gitlab/ci/config/entry/variables.rb
index 8acab605c91..6fd3cec2f5f 100644
--- a/lib/gitlab/ci/config/entry/variables.rb
+++ b/lib/gitlab/ci/config/entry/variables.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/config/loader.rb b/lib/gitlab/ci/config/loader.rb
index 141d2714cb6..b4c491e84a6 100644
--- a/lib/gitlab/ci/config/loader.rb
+++ b/lib/gitlab/ci/config/loader.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Config
diff --git a/lib/gitlab/ci/cron_parser.rb b/lib/gitlab/ci/cron_parser.rb
index 73f36735e35..b1db9084662 100644
--- a/lib/gitlab/ci/cron_parser.rb
+++ b/lib/gitlab/ci/cron_parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class CronParser
diff --git a/lib/gitlab/ci/mask_secret.rb b/lib/gitlab/ci/mask_secret.rb
index 0daddaa638c..58d55b1bd6f 100644
--- a/lib/gitlab/ci/mask_secret.rb
+++ b/lib/gitlab/ci/mask_secret.rb
@@ -1,9 +1,13 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci::MaskSecret
     class << self
       def mask!(value, token)
         return value unless value.present? && token.present?
 
+        # We assume 'value' must be mutable, given
+        # that frozen string is enabled.
         value.gsub!(token, 'x' * token.length)
         value
       end
diff --git a/lib/gitlab/ci/model.rb b/lib/gitlab/ci/model.rb
index 3994a50772b..fbdb84c0522 100644
--- a/lib/gitlab/ci/model.rb
+++ b/lib/gitlab/ci/model.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Model
diff --git a/lib/gitlab/ci/pipeline/chain/base.rb b/lib/gitlab/ci/pipeline/chain/base.rb
index efed19da21c..bab1c73e2f1 100644
--- a/lib/gitlab/ci/pipeline/chain/base.rb
+++ b/lib/gitlab/ci/pipeline/chain/base.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/build.rb b/lib/gitlab/ci/pipeline/chain/build.rb
index b5eb0cfa2f0..b445a872b3d 100644
--- a/lib/gitlab/ci/pipeline/chain/build.rb
+++ b/lib/gitlab/ci/pipeline/chain/build.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/command.rb b/lib/gitlab/ci/pipeline/chain/command.rb
index a53c80d34f7..05978804d92 100644
--- a/lib/gitlab/ci/pipeline/chain/command.rb
+++ b/lib/gitlab/ci/pipeline/chain/command.rb
@@ -1,4 +1,7 @@
-module Gitlab # rubocop:disable Naming/FileName
+# rubocop:disable Naming/FileName
+# frozen_string_literal: true
+
+module Gitlab
   module Ci
     module Pipeline
       module Chain
diff --git a/lib/gitlab/ci/pipeline/chain/create.rb b/lib/gitlab/ci/pipeline/chain/create.rb
index 02493c7fe02..c882241ef6a 100644
--- a/lib/gitlab/ci/pipeline/chain/create.rb
+++ b/lib/gitlab/ci/pipeline/chain/create.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/helpers.rb b/lib/gitlab/ci/pipeline/chain/helpers.rb
index bf1380a1da9..6bb3a75291b 100644
--- a/lib/gitlab/ci/pipeline/chain/helpers.rb
+++ b/lib/gitlab/ci/pipeline/chain/helpers.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/populate.rb b/lib/gitlab/ci/pipeline/chain/populate.rb
index f34c11ca3c2..633d3cd4f6b 100644
--- a/lib/gitlab/ci/pipeline/chain/populate.rb
+++ b/lib/gitlab/ci/pipeline/chain/populate.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/sequence.rb b/lib/gitlab/ci/pipeline/chain/sequence.rb
index e24630656d3..99780409085 100644
--- a/lib/gitlab/ci/pipeline/chain/sequence.rb
+++ b/lib/gitlab/ci/pipeline/chain/sequence.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/skip.rb b/lib/gitlab/ci/pipeline/chain/skip.rb
index 32cbb7ca6af..b9707d2f8f5 100644
--- a/lib/gitlab/ci/pipeline/chain/skip.rb
+++ b/lib/gitlab/ci/pipeline/chain/skip.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/validate/abilities.rb b/lib/gitlab/ci/pipeline/chain/validate/abilities.rb
index 13c6fedd831..ebd7e6e8289 100644
--- a/lib/gitlab/ci/pipeline/chain/validate/abilities.rb
+++ b/lib/gitlab/ci/pipeline/chain/validate/abilities.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/validate/config.rb b/lib/gitlab/ci/pipeline/chain/validate/config.rb
index a3bd2a5a23a..28c38cc3d18 100644
--- a/lib/gitlab/ci/pipeline/chain/validate/config.rb
+++ b/lib/gitlab/ci/pipeline/chain/validate/config.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/chain/validate/repository.rb b/lib/gitlab/ci/pipeline/chain/validate/repository.rb
index 9699c24e5b6..d88851d8245 100644
--- a/lib/gitlab/ci/pipeline/chain/validate/repository.rb
+++ b/lib/gitlab/ci/pipeline/chain/validate/repository.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/duration.rb b/lib/gitlab/ci/pipeline/duration.rb
index 30701e1de1b..de24bbf688b 100644
--- a/lib/gitlab/ci/pipeline/duration.rb
+++ b/lib/gitlab/ci/pipeline/duration.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression.rb b/lib/gitlab/ci/pipeline/expression.rb
index f57df7c5637..61d392121d8 100644
--- a/lib/gitlab/ci/pipeline/expression.rb
+++ b/lib/gitlab/ci/pipeline/expression.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/base.rb b/lib/gitlab/ci/pipeline/expression/lexeme/base.rb
index 047ab66e9b3..70c774416f6 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/base.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/base.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/equals.rb b/lib/gitlab/ci/pipeline/expression/lexeme/equals.rb
index 3a2f0c6924e..668e85f5b9e 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/equals.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/equals.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/matches.rb b/lib/gitlab/ci/pipeline/expression/lexeme/matches.rb
index 10957598f76..cd17bc4d78b 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/matches.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/matches.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/null.rb b/lib/gitlab/ci/pipeline/expression/lexeme/null.rb
index a2778716924..be7258c201a 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/null.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/null.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/operator.rb b/lib/gitlab/ci/pipeline/expression/lexeme/operator.rb
index f640d0b5855..3ebceb92eb7 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/operator.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/operator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/pattern.rb b/lib/gitlab/ci/pipeline/expression/lexeme/pattern.rb
index 9b239c29ea4..d7e6dacf068 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/pattern.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/pattern.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/string.rb b/lib/gitlab/ci/pipeline/expression/lexeme/string.rb
index 346c92dc51e..2db2bf011f1 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/string.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/string.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/value.rb b/lib/gitlab/ci/pipeline/expression/lexeme/value.rb
index f2611d65faf..ef9ddb6cae9 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/value.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/value.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/variable.rb b/lib/gitlab/ci/pipeline/expression/lexeme/variable.rb
index 37643c8ef53..85c0899e4f6 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/variable.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/variable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/lexer.rb b/lib/gitlab/ci/pipeline/expression/lexer.rb
index 4cacb1e62c9..f26542361a2 100644
--- a/lib/gitlab/ci/pipeline/expression/lexer.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/parser.rb b/lib/gitlab/ci/pipeline/expression/parser.rb
index 90f94d0b763..ed184309ab4 100644
--- a/lib/gitlab/ci/pipeline/expression/parser.rb
+++ b/lib/gitlab/ci/pipeline/expression/parser.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/statement.rb b/lib/gitlab/ci/pipeline/expression/statement.rb
index b36f1e0f865..b03611f756e 100644
--- a/lib/gitlab/ci/pipeline/expression/statement.rb
+++ b/lib/gitlab/ci/pipeline/expression/statement.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/expression/token.rb b/lib/gitlab/ci/pipeline/expression/token.rb
index 58211800b88..513d43f6fca 100644
--- a/lib/gitlab/ci/pipeline/expression/token.rb
+++ b/lib/gitlab/ci/pipeline/expression/token.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/seed/base.rb b/lib/gitlab/ci/pipeline/seed/base.rb
index db9706924bb..1fd3a61017f 100644
--- a/lib/gitlab/ci/pipeline/seed/base.rb
+++ b/lib/gitlab/ci/pipeline/seed/base.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/seed/build.rb b/lib/gitlab/ci/pipeline/seed/build.rb
index 6980b0b7aff..ef738a93bfe 100644
--- a/lib/gitlab/ci/pipeline/seed/build.rb
+++ b/lib/gitlab/ci/pipeline/seed/build.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/pipeline/seed/stage.rb b/lib/gitlab/ci/pipeline/seed/stage.rb
index 2b58d9863a0..4775ff15581 100644
--- a/lib/gitlab/ci/pipeline/seed/stage.rb
+++ b/lib/gitlab/ci/pipeline/seed/stage.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Pipeline
diff --git a/lib/gitlab/ci/reports/test_case.rb b/lib/gitlab/ci/reports/test_case.rb
index b4d08ed257f..292e273a03a 100644
--- a/lib/gitlab/ci/reports/test_case.rb
+++ b/lib/gitlab/ci/reports/test_case.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Reports
diff --git a/lib/gitlab/ci/reports/test_reports.rb b/lib/gitlab/ci/reports/test_reports.rb
index c87bdb4a8a2..7397ff35d46 100644
--- a/lib/gitlab/ci/reports/test_reports.rb
+++ b/lib/gitlab/ci/reports/test_reports.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Reports
diff --git a/lib/gitlab/ci/reports/test_reports_comparer.rb b/lib/gitlab/ci/reports/test_reports_comparer.rb
index 726c6a11a81..11810bdc0a8 100644
--- a/lib/gitlab/ci/reports/test_reports_comparer.rb
+++ b/lib/gitlab/ci/reports/test_reports_comparer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Reports
diff --git a/lib/gitlab/ci/reports/test_suite.rb b/lib/gitlab/ci/reports/test_suite.rb
index b5f15397c0f..b0391160c15 100644
--- a/lib/gitlab/ci/reports/test_suite.rb
+++ b/lib/gitlab/ci/reports/test_suite.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Reports
diff --git a/lib/gitlab/ci/reports/test_suite_comparer.rb b/lib/gitlab/ci/reports/test_suite_comparer.rb
index 642aa593092..9cb7db5934c 100644
--- a/lib/gitlab/ci/reports/test_suite_comparer.rb
+++ b/lib/gitlab/ci/reports/test_suite_comparer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     module Reports
diff --git a/lib/gitlab/ci/trace.rb b/lib/gitlab/ci/trace.rb
index 93e219a21f9..8eccd262db9 100644
--- a/lib/gitlab/ci/trace.rb
+++ b/lib/gitlab/ci/trace.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class Trace
diff --git a/lib/gitlab/ci/yaml_processor.rb b/lib/gitlab/ci/yaml_processor.rb
index a427aa30683..39a1b52e531 100644
--- a/lib/gitlab/ci/yaml_processor.rb
+++ b/lib/gitlab/ci/yaml_processor.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Gitlab
   module Ci
     class YamlProcessor