Add yaml lint

This commit adds CI job that validates all `*.yml`
with `yamllint`.

This commit fixes all offenses present in repository.

6 files changed, 23 insertions, 15 deletions

diff --git a/.gitlab/ci/frontend.gitlab-ci.yml b/.gitlab/ci/frontend.gitlab-ci.yml
index d62b24ae97d..8656ffdbb7f 100644
--- a/.gitlab/ci/frontend.gitlab-ci.yml
+++ b/.gitlab/ci/frontend.gitlab-ci.yml
@@ -38,11 +38,11 @@ gitlab:assets:compile:
     - bundle exec rake gitlab:assets:compile
     - time scripts/build_assets_image
     - scripts/clean-old-cached-assets
-    - rm -f /etc/apt/sources.list.d/google*.list # We don't need to update Chrome here
+    - rm -f /etc/apt/sources.list.d/google*.list  # We don't need to update Chrome here
     # Play dependent manual jobs
     - install_api_client_dependencies_with_apt
-    - play_job "review-build-cng" || true # this job might not exist so ignore the failure if it cannot be played
-    - play_job "schedule:review-build-cng" || true # this job might not exist so ignore the failure if it cannot be played
+    - play_job "review-build-cng" || true  # this job might not exist so ignore the failure if it cannot be played
+    - play_job "schedule:review-build-cng" || true  # this job might not exist so ignore the failure if it cannot be played
   artifacts:
     name: webpack-report
     expire_in: 31d
@@ -141,8 +141,8 @@ jest:
   extends: .dedicated-no-docs-and-no-qa-pull-cache-job
   <<: *use-pg
   dependencies:
-  - compile-assets
-  - setup-test-env
+    - compile-assets
+    - setup-test-env
   script:
     - scripts/gitaly-test-spawn
     - date
@@ -154,8 +154,8 @@ jest:
     expire_in: 31d
     when: always
     paths:
-    - coverage-frontend/
-    - junit_jest.xml
+      - coverage-frontend/
+      - junit_jest.xml
     reports:
       junit: junit_jest.xml
   cache:
@@ -220,7 +220,7 @@ lint:javascript:report:
   before_script: []
   script:
     - date
-    - yarn run eslint-report || true # ignore exit code
+    - yarn run eslint-report || true  # ignore exit code
   artifacts:
     name: eslint-report
     expire_in: 31d
@@ -235,7 +235,7 @@ jsdoc:
   before_script: []
   script:
     - date
-    - yarn run jsdoc || true # ignore exit code
+    - yarn run jsdoc || true  # ignore exit code
   artifacts:
     name: jsdoc
     expire_in: 31d
diff --git a/.gitlab/ci/global.gitlab-ci.yml b/.gitlab/ci/global.gitlab-ci.yml
index cf87f5eb39c..aa25bad00e8 100644
--- a/.gitlab/ci/global.gitlab-ci.yml
+++ b/.gitlab/ci/global.gitlab-ci.yml
@@ -1,6 +1,6 @@
 .dedicated-runner:
   retry:
-    max: 2 # This is confusing but this means "3 runs at max".
+    max: 2  # This is confusing but this means "3 runs at max".
     when:
       - unknown_failure
       - api_failure
diff --git a/.gitlab/ci/pages.gitlab-ci.yml b/.gitlab/ci/pages.gitlab-ci.yml
index 7d9136b8213..f7b18b809b4 100644
--- a/.gitlab/ci/pages.gitlab-ci.yml
+++ b/.gitlab/ci/pages.gitlab-ci.yml
@@ -1,4 +1,3 @@
-
 pages:
   extends: .dedicated-no-docs-no-db-pull-cache-job
   before_script: []
diff --git a/.gitlab/ci/qa.gitlab-ci.yml b/.gitlab/ci/qa.gitlab-ci.yml
index 6b23af952e6..ee9e467886a 100644
--- a/.gitlab/ci/qa.gitlab-ci.yml
+++ b/.gitlab/ci/qa.gitlab-ci.yml
@@ -1,6 +1,6 @@
 package-and-qa:
   image: ruby:2.6-alpine
-  stage: review # So even if review-deploy failed we can still run this
+  stage: review  # So even if review-deploy failed we can still run this
   when: manual
   before_script: []
   dependencies: []
diff --git a/.gitlab/ci/rails.gitlab-ci.yml b/.gitlab/ci/rails.gitlab-ci.yml
index 3f0c899d704..33e7b00784c 100644
--- a/.gitlab/ci/rails.gitlab-ci.yml
+++ b/.gitlab/ci/rails.gitlab-ci.yml
@@ -136,7 +136,7 @@ setup-test-env:
   stage: prepare
   script:
     - bundle exec ruby -Ispec -e 'require "spec_helper" ; TestEnv.init'
-    - scripts/gitaly-test-build # Do not use 'bundle exec' here
+    - scripts/gitaly-test-build  # Do not use 'bundle exec' here
   artifacts:
     expire_in: 7d
     paths:
@@ -342,8 +342,8 @@ coverage:
     name: coverage
     expire_in: 31d
     paths:
-    - coverage/index.html
-    - coverage/assets/
+      - coverage/index.html
+      - coverage/assets/
   except:
     - /(^docs[\/-].*|.*-docs$)/
     - /(^qa[\/-].*|.*-qa$)/
diff --git a/.gitlab/ci/yaml.gitlab-ci.yml b/.gitlab/ci/yaml.gitlab-ci.yml
new file mode 100644
index 00000000000..401318d2df2
--- /dev/null
+++ b/.gitlab/ci/yaml.gitlab-ci.yml
@@ -0,0 +1,9 @@
+# Yamllint of *.yml for .gitlab-ci.yml.
+# This uses rules from project root `.yamllint`.
+lint-ci-gitlab:
+  extends: .dedicated-runner
+  before_script: []
+  dependencies: []
+  image: sdesbure/yamllint:latest
+  script:
+    - yamllint .gitlab-ci.yml .gitlab/ci lib/gitlab/ci/templates