MySQL backend with gitlab 7.5

Hi,

I have an existing 7.0 gitlab install working with MySQL on one cloud node, I have built a new cloud server and have installed gitlab 7.5 and updated /etc/gitlab/gitlab.rb to use mysql as the adapter:

# Check and change the external_url to the address your users will type in their browser
external_url='*.*.*.*'

# Disable postgres
postgresql['enable'] = false

gitlab_rails['db_adapter'] = 'mysql2'
gitlab_rails['db_username'] = '****'
gitlab_rails['db_password'] = '****'
gitlab_rails['db_database'] = 'gitlabhq_production'

gitlab_ci['db_adapter'] = 'mysql2'
gitlab_ci['db_username'] = '****'
gitlab_ci['db_password'] = '****'
gitlab_ci['db_database'] = 'gitlabhq_production

I have exported the old gitlab 7.0 database and imported onto the new server. When I try to access gitlab it throws a 500 error and looking at the production log file I see the following:

Started GET "/" for 194.247.246.242 at 2014-12-05 09:14:02 +0000

PG::Error (could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
):
  activerecord (4.1.1) lib/active_record/connection_adapters/postgresql_adapter.rb:881:in `initialize'
  activerecord (4.1.1) lib/active_record/connection_adapters/postgresql_adapter.rb:881:in `new'
  activerecord (4.1.1) lib/active_record/connection_adapters/postgresql_adapter.rb:881:in `connect'
  activerecord (4.1.1) lib/active_record/connection_adapters/postgresql_adapter.rb:568:in `initialize'
  activerecord (4.1.1) lib/active_record/connection_adapters/postgresql_adapter.rb:41:in `new'
  activerecord (4.1.1) lib/active_record/connection_adapters/postgresql_adapter.rb:41:in `postgresql_connection'
  activerecord (4.1.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:435:in `new_connection'
  activerecord (4.1.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:445:in `checkout_new_connection'
  activerecord (4.1.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:416:in `acquire_connection'
  activerecord (4.1.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:351:in `block in checkout'

Ho do I configure all of the ruby gems to use mysql as the DB?

Thanks for your input.