12factor/content/admin-processes.md

XI. Admin processes

One-off admin/management tasks

The process formation represents the array of processes that are used to do the app's regular business (such as handling web requests) as it runs. Separately, developers will often wish to do one-off administrative or maintenance tasks for the app, such as:

• Running database migrations (e.g. manage.py syncdb in Django, rake db:migrate in Rails).
• Running a console (also known as a REPL shell) to run arbitrary code or inspect the app's models against the live database. Most languages provide a REPL by running the interpreter without any arguments (e.g. python or node) or in some cases have a separate command (e.g. irb for Ruby, rails console for Rails).
• Running one-time scripts committed into the app's repo (e.g. php scripts/fix_bad_records.php).

Twelve-factor apps are best written in languages which provide a REPL shell out of the box, and which make it easy to run one-off scripts. In a local deploy, developers invoke one-off admin processes by a direct shell command inside the app's checkout directory. In a production deploy, developers can use ssh or other remote command execution mechanism provided by that deploy's execution environment to run such a process.