Fixing a 'Connecting to database specified by database.yml' Loop

Occasionally an app is re-deployed but won't start. You open the Rails log (at log/production.log) and see 'Connecting to database specified by database.yml' being outputted, again and again, in a loop.

How to fix?

The good news is that seeing 'Connecting to database specified by database.yml' rarely has anything to do with the database at all! It's usually due to a syntax error in your app - in a model, initializer, or controller. SSH into the server, navigate to the root folder of the Rails app, and run rails console production. Rails will attempt booting the console for the production environment. If there is a syntax error, this will be caught here and you will get an error message telling you exactly where to look to fix the error.

If there is no syntax error, you actually do have a connection problem. This can usually be fixed by updating your database.yml in the following ways.

  1. First, change host: localhost to host: Some servers don't interpret localhost correctly.
  2. If that doesn't work, try adding the port number. For example, mysql generally runs on port 3306.
  3. If that doesn't work, try adding the socket path. For example, mysql's socket path is usually at: /var/run/mysqld/mysqld.sock

So your database.yml block should look like this:

  adapter: mysql2
  encoding: utf8
  database: database_name
  username: database_user
  password: database_password
  port: 3306
  socket: /var/run/mysqld/mysqld.sock
  pool: 5
  timeout: 5000

You can also check from the console if your connection is working running ActiveRecord::Base.connected?.