Make sure db:check-schema can catch corrupted structure.sql

This is done by migrating to the previous major version in
`db:check-schema` and then run migrations, it'll only be basing on
`db/structure.sql` from last major version rather than blindly using the
currently committed `db/structure.sql`.

.gitlab/ci/rails.gitlab-ci.yml

@@ -345,10 +345,13 @@ db:migrate:reset:
 
 db:check-schema:
   extends:
-    - .db-job-base
+    - db:migrate-from-previous-major-version
     - .rails:rules:ee-mr-and-default-branch-only
+  variables:
+    TAG_TO_CHECKOUT: "v14.4.0"
   script:
-    - source scripts/schema_changed.sh
+    - run_timed_command "bundle exec rake db:migrate"
+    - scripts/schema_changed.sh
     - scripts/validate_migration_timestamps
 
 db:check-migrations:
@@ -367,7 +370,8 @@ db:migrate-from-previous-major-version:
     SETUP_DB: "false"
     PROJECT_TO_CHECKOUT: "gitlab-foss"
     TAG_TO_CHECKOUT: "v13.12.9"
-  script:
+  before_script:
+    - !reference [.default-before_script, before_script]
     - '[[ -d "ee/" ]] || export PROJECT_TO_CHECKOUT="gitlab"'
     - '[[ -d "ee/" ]] || export TAG_TO_CHECKOUT="${TAG_TO_CHECKOUT}-ee"'
     - retry 'git fetch https://gitlab.com/gitlab-org/$PROJECT_TO_CHECKOUT.git $TAG_TO_CHECKOUT'
@@ -376,6 +380,7 @@ db:migrate-from-previous-major-version:
     - run_timed_command "bundle exec rake db:drop db:create db:structure:load db:migrate db:seed_fu"
     - git checkout -f $CI_COMMIT_SHA
     - SETUP_DB=false USE_BUNDLE_INSTALL=true bash scripts/prepare_build.sh
+  script:
     - run_timed_command "bundle exec rake db:migrate"
 
 db:rollback:

scripts/schema_changed.sh

 #!/bin/sh
 
-schema_changed() {
-  if [ ! -z "$(git diff --name-only -- db/structure.sql)" ]; then
-    printf "Schema changes are not cleanly committed to db/structure.sql\n"
-    printf "The diff is as follows:\n"
-    diff=$(git diff -p --binary -- db/structure.sql)
-    printf "%s" "$diff"
-    exit 1
-  else
-    printf "Schema changes are correctly applied to db/structure.sql\n"
-  fi
+if [ ! -z "$(git diff --name-only -- db/structure.sql)" ]; then
+  printf "Schema changes are not cleanly committed to db/structure.sql\n"
+  printf "The diff is as follows:\n"
+  diff=$(git diff -p --binary -- db/structure.sql)
+  printf "%s" "$diff"
+  exit 1
+else
+  printf "Schema changes are correctly applied to db/structure.sql\n"
+fi
 
-  if [ ! -z "$(git add -A -n db/schema_migrations)" ]; then
-    printf "Schema version files have not been committed to the repository:\n"
-    printf "The following files should be committed:\n"
-    diff=$(git add -A -n db/schema_migrations)
-    printf "%s" "$diff"
-    exit 2
-  else
-    printf "Schema changes are correctly applied to db/structure.sql and db/schema_migrations/\n"
-  fi
-}
-
-schema_changed
+if [ ! -z "$(git add -A -n db/schema_migrations)" ]; then
+  printf "Schema version files have not been committed to the repository:\n"
+  printf "The following files should be committed:\n"
+  diff=$(git add -A -n db/schema_migrations)
+  printf "%s" "$diff"
+  exit 2
+else
+  printf "Schema changes are correctly applied to db/structure.sql and db/schema_migrations/\n"
+fi