Question

I am working on a localhost app which is backed by a MySQL database. However I would like to deploy to Heroku which I have read is bacekd by PostGreSQL.

What is the best way of doing so? I have thought of doing this in the Gemfile:

group :development do
 gem 'mysql2'
end

group :test do
 gem 'pg'
end

But, how would I configure the database.yml?
Is this the correct approach?

Answer 1

This page has an example configuration:

Tutorial: Rails 3.2 with Ruby 1.9.3 on Heroku · RailsApps

That tutorial assumes you have SQLite locally. If you want MySQL, just use in your Gemfile

group :development, :test do
  gem 'mysql2'
end
group :production do
  gem 'pg'
end

But, how would I configure the database.yml

You do not have to do any special setup; Heroku will generate it for you once you push.

Note (from Heroku):

We highly recommend using PostgreSQL during development. Maintaining parity between your development and deployment environments prevents subtle bugs from being introduced because of differences between your environments.

Local gems note (from the tutorial):

Run bundle install --without production to update your gems. The flag --without production allows you to skip local installation of the pg gem; otherwise, you will have to install PostgreSQL locally (the pg gem won’t install if PostgreSQL is not installed).