Enabling the maintenance page

Occasionally, we will need to make changes to our application that requires downtime. The proper way to do this is to put up a maintenance page that displays a friendly message and respond to all the incoming HTTP requests with a 503 Service Unavailable status.

Doing this will keep our users informed and also avoid any negative SEO effects. Search engines understand that when they receive a 503 response, they should come back later to recrawl the site. If we didn't use a maintenance page and our application returned a 404 or 500 error instead, it's possible that a search engine crawler might remove the page from their index.

How to do it...

Let's open up a terminal and navigate to one of our Heroku projects to begin with, using the following steps:

1. We can view if our application's maintenance page is currently enabled with the maintenance command:

   $ heroku maintenance
    off
   

2. Let's try turning it on. This will stop traffic from being routed to our dynos and show the maintenance page as follows:

   $ heroku maintenance:on
   Enabling maintenance mode for load-tester-rails... done
   

3. Now, if we visit our application, we'll see the default Heroku maintenance page:
   
4. To disable the maintenance page and resume sending users to our application, we can use the maintenance:off command:

   $ heroku maintenance:off
   Disabling maintenance mode for lo
   ad-tester-rails... done
   

See also

• To learn how to customize the maintenance page, take a look at Chapter 4, Production-ready with Heroku