Sinatra + Heroku + Datamapper deploy issues with dm-sqlite-adapter

Question

For some reason, heroku tries to require dm-sqlite-adapter, even though it should use Postgres here. Note, that this happens when I open any URL - not during the git push itself

Answer 1

Well, too many Rails apps on Heroku, I took the shared db presence for granted. heroku config showed neither DATABASE_URL or SHARED_DATABASE_URL set.

Issuing heroku addons:add shared-database:5mb solved the problem.

Strange, that the db wasn't automatically added, despite having 'pg' gem in Gemfile.

Quote from http://devcenter.heroku.com/articles/cedar:

A Heroku shared PostgreSQL database (shared-database:5mb) will be automatically added to your app in any of the following cases:

• The app is a Rails application
• The pg gem is specified in the Gemfile

Answer 2

Try doing DataMapper.setup(:default, ENV['DATABASE_URL'] || 'postgres://user:password@hostname/data/mydatabase.db') instead. Heroku is probably looking at the protocol, and therefore requiring SQLite’s dependencies.