If you want to quickly disable your application, run:

cap deploy:web:disable

It will use the project:disable task with symfony 1.x, or will install a maintenance.html page with Symfony2.

To enable the application, just run:

cap deploy:web:enable

Same here, it will use the project:enable task with symfony 1.x, and will remove the maintenance.html page with Symfony2.

For Symfony2 users, you can customize the page by specifying the REASON, and UNTIL environment variables:

cap deploy:web:disable \
REASON="hardware upgrade" \
UNTIL="12pm Central Time"

You can use a different template for the maintenance page by setting the :maintenance_template_path variable in your deploy.rb file. The template file should either be a plaintext or an erb file.