How do I open a Rails console on a production server?

The command

bin/kamal app exec --interactive --reuse 'bin/rails console'

--reuse is the part that matters. Without it Kamal starts a fresh container, which works but boots slower and, more importantly, is not the process serving traffic. With it you are inside the live container.

For a one-off that does not need a prompt, skip the console entirely:

bin/kamal app exec 'bin/rails runner "puts Account.count"'

Everything is account scoped

This is the rule the console does not enforce for you. Customer data belongs to an Account, and queries go through it:

account = Account.find_by(name: "Acme")
account.projects.count

Reaching for a bare model class works and is exactly how you leak one customer's rows into another customer's view when you paste the result somewhere. Operate through the account.

To act as a signed-in user, create a session rather than stubbing Current:

Current.session = User.find_by(email_address: "[email protected]").sessions.create!

Before you run a write

Two habits worth keeping. Read the query back before you run the update, and prefer a scoped update! over update_all, which skips validations and callbacks silently.

account.projects.where(archived: true).count   # look first

When the console is the wrong tool

Anything you will do more than twice belongs in a rake task in lib/tasks, where it can be read, reviewed and tested. The console is for the one-off and the investigation. A recurring data fix run by hand at a prompt is a bug report waiting to happen.

Anything that should happen on a schedule belongs in a job instead, enqueued with perform_later and listed in config/recurring.yml. Solid Queue runs it inside the same container, so there is no separate worker host to keep alive and nothing extra to deploy.