Migrate default intervalstyle in database

By switching the `intervalstyle`, we assume to fix CODEOCEAN-FT. It is caused by by PgBouncer providing different database connections to Rails that might behave differently.

README.md

@@ -50,6 +50,7 @@ In order to execute code submissions using the [DockerContainerPool](https://git
 
 - We recommend using [Capistrano](https://capistranorb.com/) for deployment.
 - Once deployed, CodeOcean assumes to run exclusively under a (sub)domain. If you want to use it under a custom subpath, you can specify the desired path using an environment variable: `RAILS_RELATIVE_URL_ROOT=/codeocean`. Please ensure to rebuild all assets and restart the server to apply the new path.
+- When using [PgBouncer](https://www.pgbouncer.org), please make sure to correctly set the `intervalstyle` to `iso_8601` for the database. Otherwise, the application will not be able to parse timestamps correctly. See [a similar issue here](https://gitlab.com/gitlab-org/gitlab/-/issues/349912) and [our migration](./db/migrate/20221206221333_set_database_interval_style.rb) for more details.
 
 ## Monitoring
 - We use a [Prometheus Exporter](https://github.com/discourse/prometheus_exporter) and a [Telegraf Client](https://github.com/jgraichen/telegraf-ruby)

db/migrate/20221206221333_set_database_interval_style.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class SetDatabaseIntervalStyle < ActiveRecord::Migration[7.0]
+  # We set the intervalstyle to ISO 8601 for the current database.
+  # Without this change, a transaction-based PgBouncer might cause
+  # issues with when switching between different sessions (e.g., by
+  # returning intervals in the default intervalstyle).
+
+  def change
+    connection = ActiveRecord::Base.connection
+    dbname = connection.current_database
+
+    reversible do |dir|
+      dir.up do
+        execute <<~SQL.squish
+          ALTER DATABASE "#{dbname}" SET intervalstyle = 'iso_8601';
+        SQL
+      end
+
+      dir.down do
+        execute <<~SQL.squish
+          ALTER DATABASE "#{dbname}" SET intervalstyle = 'postgres';
+        SQL
+      end
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.0].define(version: 2022_12_04_120508) do
+ActiveRecord::Schema[7.0].define(version: 2022_12_06_221333) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_trgm"
   enable_extension "pgcrypto"

db/seeds.rb

@@ -22,6 +22,10 @@ end
 Rails.application.eager_load!
 (ApplicationRecord.descendants - [ActiveRecord::SchemaMigration, User]).each(&:delete_all)
 
+# Set the default intervalstyle to iso_8601
+dbname = ApplicationRecord.connection.current_database
+ApplicationRecord.connection.exec_query("ALTER DATABASE \"#{dbname}\" SET intervalstyle = 'iso_8601';")
+
 # delete file uploads
 FileUtils.rm_rf(Rails.public_path.join('uploads'))