Support for post deployment migrationsbackground-migrations

These are regular Rails migrations that are executed by default. A user
can opt-out of these migrations by setting an environment variable
during the deployment process.

Fixes gitlab-org/gitlab-ce#22133

1 files changed, 12 insertions, 0 deletions

diff --git a/config/initializers/0_post_deployment_migrations.rb b/config/initializers/0_post_deployment_migrations.rb
new file mode 100644
index 00000000000..0068a03d214
--- /dev/null
+++ b/config/initializers/0_post_deployment_migrations.rb
@@ -0,0 +1,12 @@
+# Post deployment migrations are included by default. This file must be loaded
+# before other initializers as Rails may otherwise memoize a list of migrations
+# excluding the post deployment migrations.
+unless ENV['SKIP_POST_DEPLOYMENT_MIGRATIONS']
+  path = Rails.root.join('db', 'post_migrate').to_s
+
+  Rails.application.config.paths['db/migrate'] << path
+
+  # Rails memoizes migrations at certain points where it won't read the above
+  # path just yet. As such we must also update the following list of paths.
+  ActiveRecord::Migrator.migrations_paths << path
+end